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The relationship of geodetic strain to seismicity on the island arc of Japan and Turkey

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This is a proposal which I have submitted to the USGS Earthquake Hazard Program during my stay in Canada, but it did not work since I have been informed that the research area should be focussed over …

This is a proposal which I have submitted to the USGS Earthquake Hazard Program during my stay in Canada, but it did not work since I have been informed that the research area should be focussed over the San Andreas Fault.

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  • 1. 1 C. Proposal Information Summary Attachment F 1. Regional Panel Destination: PT 2. Project Title: "The relationship of geodetic strain to seismicity in Japan and Turkey: Collaborative Research with Geological Survey of Canada and the West Virginia University ". Principal Investigator(s): Geological Survey of Canada Investigator participating in collaborative effort is Dr. Ali O. Oncel National Earthquake Hazards Program, Geological Survey of Canada, Ottawa, Ontario., Canada K1A OY3 3. (Tel: (613) 9473520, Fax: (613) 992-8836, (oncel@seismo.nrcan.gc.ca) West Virginia University Investigator participating in collaborative effort is Dr. Thomas H. Wilson West Virginia University 419 White Hall, POB 6300 Department of Geology and Geography Morgantown, WV 26506 ((304) 293 5603 x4316), ((304) 293 6522), (tom.wilson@mail.wvu.edu) 4. Authorized Institutional (Name)(Institute/Organization (Street Address/P.O. Box) Name) Representative: (Organizational Unit) (City, State, Zip Code) (Telephone Number), (FAX Number), (E-mail Address) 5. Element Designation: Element II 6. Key Words: neotectonics, seismotectonics, seismic zonation 7. Amount Requested: $23,823 for fiscal year 2003 from WVU 8 Proposed Start Date: (October 1, 2002) 9. Proposed Duration: 12 months 10. New or Renewal Proposal; NEW 11. Active Earthquake-related Research (List project title and funding source for all active awards). Wilson currently has no funded earthquake–related research. 12. Has this proposal been submitted to any other agency for funding if so, which? Not submitted elsewhere 13. Proposal Abstract (See section E) 14. Proposal Budget Summary (See section F)
  • 2. 2 Table of Contents A. Application for Federal Assistance, Standard Form (SF) 424 B. Assurances and Certifications C. Proposal Information Summary (Attachment F) 1 D. Table of Contents 2 E. Abstract 3 F. Proposal Budget (Attachment E) 4 G. Proposal Body 5 G1. Significance of the project 5 G2. Project Plan 5 Basic Hypothesis 5 Background 5 Conceptual Framework 6 Data Sources 8 Data Analysis Procedures 8 Research Tasks 10 Geological Survey of Canada 10 see Collaborative submission by Dr. Wilson, West Virginia University * G3. Final report and dissemination 12 G4. Related efforts 12 References 15 G5. Project personnel 18 G6. Institutional qualifications 19 G7. Project management plan 19 G8. Current support and pending applications 20 G9. Continuation projects 20
  • 3. 3 The relationship of geodetic strain to seismicity on the island arc of Japan and Turkey Tom Wilson, Department of Geology and Geography, West Virginia University, Morgantown, WV, In Collaboration with - Dr. Ali Oncel, Earthquake Hazards Program, Geological Survey of Canada, Ottawa, Ontario., Canada. K1A OY3. E. Abstract Research proposed herein is a collaborative effort between West Virginia University and the Geological Survey of Canada. Our research effort is designed to evaluate the relationship of geodetic strain to earthquake seismicity distribution, rate and magnitude. The basic hypothesis to be tested by this research is whether the relationship between seismicity and geodetic strain will have variable, but statistically significant correlation that will provide information useful to seismic hazard assessment. Our study will be conducted using geodetic strain and seismicity data from Japan and Turkey. We seek to determine whether significant correlations exist between the patterns of seismicity, magnitude and earthquake frequency with geodetic strain and whether these relationships are indicative of increased potential of earthquake hazard. Strain release taking place in Japan and Turkey is an outgrowth of complex plate interactions. Seismicity in Japan occurs along three convergent plate boundaries that include two TTT type Triple Junctions, and complex transpressional interactions for example along the Nankai and Suruga troughs and Kinki Triangle. In our study, we will use horizontal area strain data compiled by the Geographical Survey Institute of Japan (see http://cais.gsi.go. jp/HIZUMI/hizumi7.html) for 110 year (1883-1994) and 10 year (1985-1994) time periods. Available strain data consist of area strain, major and minor axial length and orientation, and maximum shear strain. Vertical uplift and subsidence over these time frames have not been measured. Earthquake data used in this study comes from three earthquake databases that include: 1) Usami's (1996) historical catalogue from 1600 to 1884, 2) Utsu's (1980) catalogue for the time period between 1885 and 1925, 3) the instrumental catalogue compiled from the Japan Meteorological Agency (JMA) data file for the time period between 1926 and 1997. Data from Turkey consists of seismicity data from the Kandilli Observatory and Research Institute (KOERI) covering the region between 23-31°E and 33-45°N. This data is discussed by Oncel and Wilson (2002). The tectonic setting of this area is also quite diverse and includes a major strike-slip zone (the Northern Anatolian Fault Zone), extensional complex, and a subduction zone. Detailed GPS derived plate velocity measurements throughout the area are presented by McClusky et al. (2000). We plan to correlate strain data with seismicity using local computations of Gutenberg-Richter b- values, seismic activity rates (a-values) and generalized fractal dimensions (Dq) throughout Japan and Turkey over comparable time intervals. The Gutenberg-Richter b-value is the slope of the frequency- magnitude relationship and provides a relative measure of the likelihood of large and small magnitude seismicity in a region. The activity rate, a, represents the intercept derived from the Gutenberg-Richter or frequency-magnitude plot and describes the background levels of seismicity within an area. The correlation between strain, seismicity and the fractal properties of epicenter distribution will be evaluated locally throughout Japan and Turkey. In summary, we will conduct an investigation into the uses of fractal analysis to characterize complex properties and patterns of earthquake seismicity and to undertake direct comparison of seismicity to strain and maximum magnitude variation. The correlation of strain () to seismicity (a, and b-values) is the central issue addressed in this research proposal; however, we will also consider interrelationships between these parameters and distributions of maximum magnitude seismicity. Our research evaluates interrelationships between complex non-linear seismotectonic processes. Quantification and analysis of these interrelationships will help identify and differentiate between normal and abnormal conditions and thus provide information of value to seismic hazard assessment, not only in Japan and Turkey, but also throughout earth's active tectonic regions.
  • 4. 4 F: Proposed budget Project Title: The relationship of geodetic strain to seismicity in Japan and Turkey Proposed Start Date: October 1, 2002 Principal Investigators: Dr.Ali Oncel, National Earthquake Hazards Program, Geological Survey of Canada, 7 Observatory Crescent, Ottawa, K1a OY3 In Collaboration with Dr. Tom Wilson, Department of Geology and Geography, West Virginia University, Morgantown, WV Proposed Completion Date: Sept. 31st 2003. Task I (Oncel) Year 1 1. Salary Task I PI (Oncel, 3 summer months) $6400 2. Publication Charge Task PI (at 23.9%) $2000 3. Supplies Plotter paper $250 Laminate $100 Ink Jet/laser Cartridges $400 Report Prep. Supplies $175 Research Reports/maps/books $250 4. Travel Task PI (conference) $3,000 5. Total Direct Costs $12,575 6. Overhead (46%) $1125 7/8. Total Cost to USGS for GSC $13,700 Budget Justification (to be modified) 1. Salary: Dr. Oncel will work on the project for 3 months full time during the summer of 2002/03 ($2,133/month) and will cost share 70% ($3,436) of his time during the regular working year. 2. Publication Charge is paid for reprints and necessary books for study. 3. Supplies: Various supplies related to the plotting of maps, preparation of poster materials for a professional meeting, report preparation materials, purchase of reference maps and books is requested to assist in the preparation of quality professional presentations and research reports. 4. Travel: Dr. Oncel will attend at least one professional meeting of EGS and AGU to present the research results. $3000 is requested for conference attendance. The balance will be obtained from department and university grants. 5. Total Direct Costs: $12,575 6. Indirect Costs: GSC overhead is charged at the rate of 46% on all items with the exception of equipment whose value exceeds $1000. Indirect costs are based on total direct cost minus $2000 for computer equipment. Total Indirect Costs are $13,700 7/8. Total Project Cost: $13,700
  • 5. 5 G. Proposal Body: G1. Significance of the project Objective: The main objective of the proposed research effort is to evaluate the relationship of geodetic strain to earthquake seismicity distribution, rate and magnitude. Scientific Significance: The scientific significance of this research is that its outgrowths provide information of value to earthquake hazard assessment. We will use fractal analysis to characterize complex properties and patterns of earthquake seismicity and to undertake direct comparison of seismicity to strain and maximum magnitude variation. The correlation of strain (horizontal crustal strains, plate velocity, and differential plate velocity) to seismicity is the central issue addressed in this research proposal. Our research evaluates interrelationships between complex non-linear seismotectonic processes. Quantification and analysis of these interrelationships will help identify and differentiate between normal and abnormal conditions and thus provide information of value to seismic hazard assessment, not only in Japan and Turkey, but throughout earth's active tectonic regions. G2. Project Plan Basic Hypothesis The basic hypothesis to be tested by this research is whether the relationship between seismicity and geodetic strain will have variable, but statistically significant correlation that will provide information useful to seismic hazard assessment. Background Tectonic Framework of the Study areas Our study will be conducted using geodetic strain, GPS plate velocity and seismicity data from the Japan and Turkey. Strain release taking place along the length of the Japan Island Arc is an outgrowth of complex plate interactions. The islands of Japan (Figure 1) are comprised of ancient crustal fragments, accretionary complexes and suture zones whose formation spans the Phanerozoic and Proterozoic eons. Transpressional plate convergence in the fore-arc region of southwestern Japan has produced strike slip offsets through the system of complexes in the outer arc region along the Median Tectonic Line (MTL Figures 1). The MTL lies along the northern boundary of the Nankai fore-arc sliver, which is driven westward by oblique subduction of the Philippine Sea Plate beneath the Eurasian Plate in southwest Japan (Figure 2) (Isozaki 1996). Movement along the MTL is predominantly experienced significant reverse motion, at least during the Plio-Pleistocene (Tsukuda 1997) right-lateral strike-slip (Gutscher and Lallemand, 1999) and is suggested to exceed 10 mm/yr by GPS; however quaternary dextral strike-slip motion along MTL is widely believed to have occurred. The reverse component is southeast vergent (Hashimoto et al., 2000). The 1995 Hyogo-ken Nanbu (M7.2) earthquake occurred along a northeast trending strike-slip fault known as the Nojima fault that branches off the MTL and extends through the island of Awaji to Kobe (Tadokoro et al., 1999; Kikuchi and Kanamori, 1996). Many of the active faults in the Hyogo-ken Nanbu (Kobe) area have significant vertical displacement (Yokokura et al 1997). Displacements along the Nojima fault have been clearly mapped on the island of Awaji. Mapped (1995?) displacements reveal as much as 1.7 meters of right-lateral displacement along with a maximum of 1.3 meters of vertical displacement. Active fault zones extending inland to the northeast of Kobe and the area north of the MTL through Lake Biwa to the Japan Sea form the Kinki Triangle (Figures 1). The Kinki Triangle is defined by active strike slip faults along its northeast and northwest sides (Toda et al. 1998.). North-south trending reverse faults are dominant within the triangle (Toda et al. 1998). The Kinki Triangle in addition to the MTL are believed to, in part, accommodate shortening of the Eurasian plate against the North American plate across the Itoigawa-Shizuoka Tectonic Line (ISTL) (Figures 1).
  • 6. 6 Seismicity within the Kinki Triangle is believed to be interrelated to seismicity along the Nankai trough, which, in turn is influenced by seismicity in the Fossa Magna and Sagami trough regions (Lu et al.,1999). The ISTL is believed to be an incipient subduction zone (Nakamura 1983; Kobayashi 1983) across which northeastern Japan is subducting beneath southwestern Japan. Recent excavation along the ISTL reveals the extent and possible recurrence interval of large earthquakes occurring on individual segments of the ISTL during the last 5,000 to 7,000 years (Okumura et al. 1994; Okumura 1997). A low velocity zone observed in a seismic refraction profile across the ISTL (Ikami et al. 1986) coincides with a southwest dipping low density zone inferred from gravity models along the profile (Wilson and Kato 1992 and 1995). A zone of seismicity in the back-arc area of northern Japan punctuated by recent large earthquakes (M7.7 and M7.3 in 1983 and 1993, respectively), is suggested to be associated with the northern extension of this subduction zone (Figure 1) along the western boundary of the North American Plate (e.g. Shimokawa 1997) in northeastern Japan. The slow convergence of the Eurasian Plate (3mm/yr) toward the North American Plate across the ISTL is interrupted on its southern end by collision with the Philippine Sea Plate. The meeting point of these three plates forms a TTT triple junction just north of Mt. Fuji. The Philippi ne Sea Plate carries the Izu-Bonin arc northward in this area. This arc-arc collision produces the V-shaped indentation known as the Kanto Syntaxis west of Tokyo (Isozaki 1996) (Figure 1). Paleomagnetic studies of Late Miocene diorite bodies in the Kanto Mountains suggest that the syntaxis formed in the late Miocene or earlier (Takahashi and Nomura 1988). Considerable vertical movement has occurred throughout Japan during the Quaternary. A maximum uplift of more than 1500 meters is observed in the Hida Mountains region of north central Japan while more than 1000 meters of subsidence is observed in the Kanto Plain region near Tokyo. The high relief regions of central Japan, as a whole, coincide with areas of high Quaternary uplift. The eastern boundary of the high relief/high uplift region of central Japan coincides approximately with the Tanakura Tectonic Line (TTL) in northeastern Japan. To the west, this high relief/uplift region is bounded by the eastern margin of the Kinki Triangle. The active fault pattern on the other hand reveals an abrupt decrease in fault density to the east across the ISTL (see Oncel, et al, 2001; Wilson et al., in review). The Kinki Triangle to the west is also intensely faulted. However faulting associated with the triangle has not led to significant topographic development within the triangle itself. This suggests that displacements along the north-south trending reverse faults in the interior of the Kinki Triangle have not been extensive. Conceptual Framework Seismicity, epicenter distribution, magnitude and their interrelationships Spatial patterns of earthquake distribution and temporal patterns of occurrence are demonstrated to be fractal using the two-point correlation dimension Dc (e.g. Kagan and Knopoff, 1980; Sadowsky et al., 1984). Similar observations have been made of laboratory scale seismicity associated with microfracturing in rocks (Mogi, 1962; Scholz, 1968; Main et al., 1990, Xie., 1992) and the fractal correlation dimension (Hirata et al., 1987). The Gutenberg-Richter b-value has been suggested to represent a generalized "fractal dimension" of earthquake magnitude distributions (Aki 1981; Turcotte 1992). Sornette et al. (1991) note that this interpretation assumes a dislocation model for the seismic source and also requires a scale invariant recurrence interval. The relationship has nevertheless been proven to apply on empirical grounds for tensile fracture in the laboratory (Hatton, Main & Meredith, 1993). While the significance of the relationship at larger scale remains in question, the relationship is implicitly assumed in much of the recent literature on the non-linear dynamics of earthquakes (Main, 1996). However, the b-value has been shown to vary systematically before and during major earthquakes (Smith, 1986) and in laboratory tests under controlled conditions (Main et. al., 1990). This variation has been attributed to rock heterogeneity (Mogi, 1962) or heterogeneous stress distribution (Scholz, 1968). The most recent studies (Main et al., 1990) have extended and unified these observations into a single negative correlation between b and the
  • 7. 7 degree of stress concentration measured by the relative stress intensity factor K/Kc, where Kc is the fracture toughness. Two hypotheses suggest that the slope (b) and intercept (a) derived from the Gutenberg-Richter relation provide useful information about earthquake behavior and fault zone orientation (Jackson and Kagan, 1999; Wiemer and Wyss, 1997). Jackson and Kagan (1999) suggested that the a-value or activity rate maps the most likely locations of asperities (higher a-value), based on analysis of short term seismicity in the NW Honshu region before the July 18, 1992 (Mw=6.9 earthquake) (see also Figure 5 of Jackson and Kagan, 1999). Differences noted by Jackson and Kagan in terms of filling or unfilling the regions with higher activity rates (a-value) indicates that research on earthquake forecasting requires analysis of changes in b-value and clustering (D). Also, note that the epicentral location of the Izmit earthquake (Mw=7.4) corresponds to a region associated with higher a-value and average b-value. However, the probability of the Mw =7.4 earthquake predicted the Gutenberg-Richter relation is lower than the actual observed rate of occurrence of similar magnitude events (see also Figure 4 b, c of Oncel and Wyss). Comparing the maps of activity rate (a-value) and mean magnitude (b-value) shows irregular spatial patterns in the variation of b-value (Figure 4 of Wyss and Oncel, 2000). The comparison reveals regions with higher seismic hazard based on the two different models: one based on variations in b-value (Wiemer and Wyss, 1999) and the other on variations in the a-value (Jackson and Kagan, 1999). A third hypothesis, proposed by Wyss et al., (2000b) and Oncel and Wyss (2000), unifies the relationship between a and b. This approach estimates the minima in local recurrence times (TL), which can be related directly to the local probability (PL=1/TL) of events having a given magnitude. The local recurrence time is derived from information contained in the heterogeneous distribution of both parameters a and b. The utility of this new measure (TL) was tested in Southern California (Wyss et al., 2000a,b) and for the subduction plate boundary along the west coast of Mexico (Zuniga and Wyss, 1999). Oncel and Wyss (2000) interpreted changes in the local minimum values of TL observed along the western extent of the Northern Anatolian Fault Zone and suggested that the rupture during the Izmit earthquake initiated at the edge of one asperity and stopped at another major asperity observed on the western end of the NAFZ. In that case, TL for a main shock during the time period covered by the catalog would be short (high a- and low b-value) (see also, Figure 4 of Oncel and Wyss, 2000). A complete description of the fractal character of seismotectonic data requires more than one fractal dimension or scaling exponent (Sornette, Vanneste & Sornette, 1991). Multifractals seem to describe various aspects of non-linear dynamic systems better than mono-fractals. This is suggested based on the existence of different subsets of the seismotectonic data related to conditions of random multiplicative processes (Redner, 1990; Xu and Burton, 1999). Multifractals (Dq) generally reflect different scale-invariant properties of earthquake processes for various values of q (=0,1,2,3,..), and need not be equal to or even positively correlated with one another. For example, the capacity dimension, D0 (i.e., for q=0), estimated by box-counting methods (Feder, 1988), measures the space-filling properties of a fracture set with respect to changes in grid-scale (Hirata, 1989a). The fractal relationship between the characteristic linear dimension of faults and b-value (e.g. Turcotte 1989) provides a measure of the relative proportion of large and small seismogenic faults (Aki, 1981; King, 1983) or cracks producing acoustic emission (Main et al., 1990). The correlation dimension, Dc, (for q=2) (Grassberger and Procaccia, 1983) measures the spacing or clustering properties of a set of points, and has also been applied both to earthquake epicenters (Kagan and Knopoff, 1980; Hirata, 1989b; De Rubeis et al., 1993; Barbano et al., 2000) and to the hypocenter distributions of acoustic emissions in laboratory experiments (Hirata et al., 1987). Multifractal measures have been used to quantify the geometrical properties of faults, fractures, earthquakes and mining-induced seismic activity (Gibovicz and Lasocki, 2001; Main, 1996). Oncel and Wilson (in review) present a detailed evaluation of the differences between D2 and D15 in three major tectonic subdivisions of Turkey. The difference between D2 and D15 is statistically significant and, on average, approximately 0.34. In some instances, D15 was found to have higher
  • 8. 8 correlation to b-value and plate velocity, whereas in other instances, the opposite was observed. The significance of the correlations also varied. In the zone of extension, for example, between the NAFZ and Hellenic Arc tectonic subdivisions, D2 and D15 correlate positively with plate velocity (V) (with r of 0.52 and 0.61 respectively). The correlation of D15 to V was significant at the  0.03 level, whereas the correlation of D2 to V was less significant with an  level of 0.09. Data Sources Horizontal area strain data has been compiled by the Geographical Survey Institute of Japan (see http://cais.gsi.go.jp/HIZUMI/hizumi7.html) into 110 year (1883-1994) and 10 year 1985-1994 time periods. Available strain data consist of area strain, major and minor axial length and orientation, and maximum shear strain. Vertical uplift and subsidence data over these time frames are not available (Should be available?). Earthquake data used in this study comes from three earthquake databases that include: 1) Usami's (1996) historical catalogue from 1600 to 1884, 2) Utsu's (1980) catalogue for the time period between 1885 and 1925, 3) the instrumental catalogue compiled from the Japan Meteorological Agency (JMA) data file for the time period between 1926 and 1997. We plan to correlate strain data with seismicity using detailed computation of the Gutenberg-Richter a- and b-values and generalized fractal dimension (Dq) throughout Japan for comparable time intervals. The Gutenberg-Richter b-value is the slope of the frequency-magnitude relationship and provides a relative measure of the likelihood of large and small magnitude seismicity in a region. The a-value is a measure of the activity rate and corresponds to the intercept of the Gutenberg-Richter relationship (see Equation 1 below).The correlation between strain, seismicity, and the fractal properties of epicenter distribution will be evaluated locally throughout Japan. Data Analysis Procedures Seismic a-value and b-value: Estimates of a- and b-value in the Gutenberg-Richter (1954) relation: log N=a-bM (1) implies a fractal relation between frequency of occurrence and the radiated energy, seismic moment or fault length, and is one of the most widely used statistical parameters to describe the size scaling properties of seismicity. b-value are least biased when computed using the maximum likelihood method (Aki, 1965), b=2.303/(Mmean-Mmin+0.05) (2) where Mmean is the mean magnitude of events M>Mmin that is the minimum magnitude of completeness in the earthquake catalogue. Accurate estimates of local changes of Mmin can be made if relatively large numbers (100 or so) of local observations are available for analysis (Wiemer and Wyss, 2000). Seismic b-value is found to be negatively correlated to mean magnitude and mean crack length (Main et al., 1992). Thus, space-time variability of b-value, is equivalent to the changes in mean magnitude of earthquakes (Wyss and Wiemer, 2000, Oncel and Wyss, 2002), and can be affected by several physical factors such as material heterogeneity, applied shear stress level (Mogi 1962; Scholz 1968; Wyss, 1973; Urbancic et al., 1992), Coulomb failure stress changes (Wyss and Wiemer, 2000; Oncel and Wyss, 2000b), thermal gradient (Warren and Latham, 1970) and complexity changes in the fault segments (Oncel et al., 2001). The value 0.05 is a correction constant that compensates for round off errors. The 95% confidence limits on the estimates of b are 1.96 /b n , where n is the number of earthquakes used to make the estimate. This yields typical confidence limits of ± 0.1 to ±0.2 for a typical sample consisting of n=100 earthquakes. Regional scale estimates of b-value generally range between 0.5 and 1.6 (e.g., Wyss et al., 2000, Oncel and Wyss, 2000b; Oncel et al., 2001,Oncel and Wilson, 2002); however, on average, the regional
  • 9. 9 scale estimates of b value are approximately equal to 1 (Frohlich and Davis, 1993; Kagan and Jackson, 1991). The a-value is directly computed as the intercept in the Gutenberg-Richter relationship. Local Recurrence Time (TL) TL can be estimated from the fractal parameters of the frequency-magnitude distribution for different target magnitudes, Mtarg; this is an important parameter that has been proven to be useful in earthquake engineering design applications (Oncel and Kijko, 2000). The local recurrence time is defined as TL(A) =T/(10(a-bMtarg) ) (3) where T is the observation period. Mtarg, the target magnitude, is set approximately equal to the historically largest observed magnitude. Using this target magnitude, it is possible to estimate the probabilistic recurrence time associated with the occurrence of local asperities (e.g., Wyss et al., 2000a,b; Oncel and Wyss, 2000a,b) since TL value is also equal to local probability (PL) given as (Wyss, 2002): PL = 1/TL(A) (4) The parameters PL and TL are proportional. A is the size of the region under investigation. It is bounded by a fixed cylindrical volume with radius r dependiing on the objectives of the study. For example, a radius r = 20 km was used in the study conducted by Oncel and Wyss (2000), while a 50 km radius was used in the study conducted by Oncel et al. (2001) and Oncel and Wilson (2002). The generalized fractal dimension Dq: Complex structures found in nature are often heterogeneous (Mandelbrot, 1982). Earthquake magnitudes and hypocenter distribution are examples of complex natural phenomena that have scale invariant structure. The evolution of ideas concerning the fractal characterization of natural phenomena has been expanded to incorporate multiple measures of fractal dimension or scaling exponent. Further explanation of the fractal character of seismological data requires more than one fractal dimension. Sornette, et al. (1993), for example, suggest that a single fractal dimension does not adequately describe geometrical irregularities since two objects with the same monofractal dimension could have significantly different properties and most geodynamical processes have varying densities (see also Baker and Golub, 1990, Pyrak-Nolte et al., 1992). The multifractal concept is a natural extension of fractal analysis to the evaluation of heterogeneous fractals (Grasberger 1983, Hentschel and Procacia 1983, Mandelbrot 1982). More detailed information concerning the fractal properties of complex variables is provided by the concept of generalized dimensions or multifractal dimensions. Multifractals are used to describe a heterogeneous fractal set. Following Grasberger (1983) and Hentschel and Procaccia (1983), the generalized dimension (Dq) is defined as follows: 0 log 1 ( 1) loglim q i i r q r D q r p      (5) where pi is the probability that a box of size r will contain part of, one or more epicenters. There are several methods that can be used to estimate the value of D q (Grasberger 1983; Hentschel and Procaccia 1983). However, in this project, we plan to use the generalized-correlation-integral method (e.g., Wang and Lee, 1996; Hirata and Imoto 1991, Godano and Caruso, 1995; Godano et al., 1999). The discrete form of the generalized correlation integral function is defined as:
  • 10. 10 )1/(1 1 1 1 )(1 )(                      q N j q j q N rRN N rC (6) The angular distance r in degrees between two events is calculated using the formula for the angular distance r in degrees between two events ))-(+(=r 212121 -1  cossinsincoscoscos (7) where (1, 1) and (2, 2) are the colatitudes () and longitudes () of the two events respectively (Hirata, 1989, Oncel et al.,1995). Multifractal dimensions are defined by fitting a straight line to a plot of log C (r) against log r (converted to a distance using 1°=111 km) as r tends to zero over a data range for the first 1.5 orders of magnitude for which the data were considered reliable. The lower bound may be determined by the epicentral resolution and the upper bound by the influence of the finite size of the study zone (Kagan and Knopoff, 1980). The spectrum of the generalized fractal dimensions (Dq , q = 0,1,2,....) of seismicity data estimated from the linear portion of the log-log plot of Cq versus distance (see Figure 4), can be used to evaluate the distribution for multifractal behavior. The better-known capacity, information and correlation dimensions correspond to values of q = 0,1,2, respectively. The differences between heterogeneous and homogeneous fractals are inferred from variations in Dq. It is the variability of Dq that identifies multifractal behavior. In contrast, a monofractal is characterized by invariant Dq and is associated with relatively homogeneous geometry at all scales. Multifractal exponents can be computed for both positive to negative values of q, and are interpreted to characterize the degree of clustering from the most to the least intensive, respectively. Fractal dimensions for negative q are believed to be most sensitive to the spatial variations occurring in relatively sparse areas of the pattern; however, errors in the estimates of D for negative q are large, so that D is highly variable and of questionable significance (Hirabayashi et al., 1992; Eneva, 1996). Uncertainty in the positive q estimates of D, on the other hand, is found to be small (Hirabayashi et al., 1992). D for positive q is suggested to be useful for differentiating between patterns of seismicity observed in high strain regions (Cowie et al., 1995). Our study is restricted to computation and analysis of fractal dimensions with positive q-values of 2 and 15. This approach is similar and an extension to the approach followed in previous research, which showed that D does not change significantly when q is greater than 15 (eg., Lei et al., 1993; Lei and Kusunose, 1999; Oncel et al., 1996 b and c; Oncel and Wilson, 2002). The general computation of distance r is given below: r x x y y z zij i j i j i j     ( ) ( ) ( )2 2 2 (1) where ( xi , y i , z i ) and ( x j , y j , z j ) are the co-ordinates of two hypocentres. Here, z is depth but generally excluded during the computation for its poor determination. In my papers, r is computed as an angular distance the same as Hirata (1989 a, b) used for considering the curvature of the space. To my opinion, equation 1 may be used especially for the mapping of fractal dimension with fixed number or area since the space will not be large or the equation 3 in my tectonophysics paper may be adjustment for including the z easily. I think, Jeremy Henderson usually uses the equation one rather the equation used in my papers. I hope that this information would be fruitful for your fractal implementation.
  • 11. 11 The full range of multifractal components D2 through D15 in Figure 4 are shown. As q increases, Dq decreases. D2, the correlation dimension, is sensitive to small changes in the density of points within small subdivisions of the pattern. Increases in D2 imply a decreased tendency of epicenters to form clusters (see Oncel et al, 1996 b and c). The higher order dimensions are increasingly sensitive to heterogeneity in the distribution of points (Baker and Gollub 1990), since D15 is usually less than D2. This suggests that seismicity is more clustered at larger scales (or in smaller areas). Research Tasks Geological Survey of Canada (Oncel) - Seismotectonic Analysis The discussion below refers to efforts undertaken by both Dr. Oncel and Dr. Wilson, however, the reviewers should refer to the collaborative efforts proposed by Dr. Wilson from the West Wirginia University. The efforts conducted by Dr. Wilson will precede, parallel and compliment various research activities proposed in this task. Individual tasks and timetable are presented below in section G7. The West Wirginia University research effort to be undertaken by Dr. Wilson will evaluate interrelationships between seismotectonic variables and geodetic strain. Dr. Wilson brings considerable expertise and many years of experience in the interrelationship analysis of non-linear complex variables in seismotectonic systems. Dr. Oncel will compile earthquake catalogues data available at JMA and present historical catalogues of Utsu [1982] and Usami [1996]. The preliminary compilation of Long-Term Earhquakes Japaneese Catalogues has also been undertaken and used in previous research (Oncel et al., 2001, Oncel and Wilson, 2002, Kijko and Oncel, 2000).. Dr.Oncel will compute the seismotectonic variables (Dq, a- and b-value, and m) locally along transects similar to those evaluated by Oncel et al (2001). Correlation between strain data and In our previous work (Oncel, et al., 2001), we computed seismotectonic variables every 20km along regional analysis lines examined earthquakes occurring in a cylindrical volume 50km in radius and 20km deep. Significant changes in strain rate appear in the preliminary comparisons between these two time periods. Figure 2 presents a comparison of maximum area strain observed over the 110 and 10 time periods. In this comparison strains observed over the 110 year time frame were divided by 11 to provide a representative 10 year average strain. The average 10 year maximum shear strain was then subtracted from the maximum shear strains measured in the recent 10 year time interval; the difference was contoured (Figure 2). The comparison reveals local areas of significant increase in compressive (negative) or extensional (positive) strain. In general the differences are greatest in the outer Japan Arc region (east and southeast coasts. Significant concentrations of local differences between the average and recent strain accumulation appear in east-central Japan. Local patterns of GPS-derived crustal velocity also reveal interesting relationships between strain and fractal measures of seismicity distribution. Seismicity and average velocites are shown for several seismic zones along the Northern Anatolian Fault Zone (NAFZ) in the Turkey study area (Figure 3). Seismic zones in the region south of the NAFZ (Figure 3) reveal unusual relationships between average plate velocity and seismic b-value. In Figure 3 we see that plate velocity to the south in zones 5, 6, 7, and 8 are characterized by relatively constant velocity (approximately 23mm/year), whereas in regions to the north (zones 1, 2, 3, and 4) the plate velocity decreases (roughly from 19mm/year to 11mm/year) to the west. These observations suggest that the Anatolian plate south of the NAFZ moves somewhat like a wrench focusing stress into the western reaches of the NAFZ. We also note that b-values generally drop to the west, indicating that greater probability of larger magnitude seismicity is characteristic of the western end of the NAFZ. The b-value drops to its lowest value in area 9 farthest to the west along the NAFZ. The suggested relationship is supported, unfortunately, through recent catastrophic earthquakes along the western end of the NAFZ. The a-values (Figure 3) also reveal interesting behavior in the vicinity of the NAFZ. In the seismic zones to the south (zones 5, 6, 7, 8, and 9) a- and b-value are highly correlated (r = 0.94). This is the general expectation: as the slope (b) increases, we would expect the intercept (a) to increase. However, for the zones adjacent to the NAFZ (zones 1, 2, 3, 4, and 9), the correlation between a and b is absent (r = 0.1). While b-value drops systematically from east to west through these zones, the a-value drops and then rises again to the west.
  • 12. 12 Dr. Wilson will also help undertake analysis of the multifractal response of epicenter distributions. As part of work we just completed in the eastern Mediterranean and western Turkey area (Oncel and Wilson, in review) we noticed that the multifractal response (logCq(r) versus log(r)) is often non-linear (see Figure 4). The response is marked more so by roughly linear segments broken by relatively abrupt transitions similar to those observed by Scholz (1995), Oncel et al. (2001), and Wilson (2001). As in the work of Oncel et al. (2001) and Wilson (2001) we may find that estimates at one scale are more stable than those at other scales. In addition, the scale of the transition may also provide insights into the distribution of seismicity. For example, Scholz (1995) notes that transitions observed along the San Andreas fault correspond to the thickness of the seismogenic zone. Wilson and Oncel will jointly evaluate the potential tectonic implications of correlation variations along the length of the Japan Arc. The occurrence of positive, negative or zero correlation between b, a, and horizontal area strain will provide insight into relationships between strain and seismicity. A variety of different relationships seem likely. Positive correlation between b and strain could occur through parallel increases, decreases or invariance of b and strain within an area. Relative increases of b are associated with a relative decrease in the probability of larger magnitude earthquakes and vice versa. In the case where increased strain is associated with an increase of b, the higher strain rate may be accommodated by gradual strain release through numerous smaller magnitude ruptures. In this case, the relationship of mutual variations in a-value will be useful. We must also distinguish between increasing tensional strain which will yield increasingly positive area strain and increasing compressive strain which will yield increasingly negative strains. Thus an increase in b would be expected if there is an increase of strain from greater negative to lesser negative area strain. If the positive correlation arises from a reduction of b and strain, the interpretation will also depend on whether the reduction in strain results from increasingly negative strain or a drop in initially positive, extensional, strain. In the first case there is added risk that larger magnitude seismicity may be imminent, in the second case, an asperity may exist. A positive correlation will also result if the variations of b and strain remain invariant across an area. In that case, nothing unusual can be inferred about the relationship. Negative correlations could arise through increases of b associated with decreases in strain or vice versa. As in the case of positive correlations, the interpretation varies. While b increases, a decrease in extensional strain (becoming less positive and trending toward zero) would be consistent with our expectations. On the other hand, an increase in b paralleled by an increasingly negative compressive strain would represent an anomalous condition. The occurrence of negative or positive correlation is not, by itself, diagnostic of anomalous conditions. In the case of a negative correlation, for example, the drop in b-value is associated with increased extension or decreased compression. The later case is anomalous and suggests a possible increased seismic hazard. Areas that lack significant positive or negative correlation between strain and seismicity are likely to occur in transitions from positive to negative correlation or in areas where the fluctuations of individual parameters are random and statistically insignificant. Uncorrelated behavior may be due to processes occurring at spatial scales beneath the resolution of our analysis. The correlation of strain to seismicity (TL, and a- and b-values) is the central issue of this research proposal; however, we will also consider interrelationships between b, Dq, strain and TL with distribution of maximum magnitude seismicity. Our research focuses on the interrelationships between complex variables. By considering the seismotectonic significance of observed relationships it may be possible to identify useful measures of seismic hazard and potentially hazardous conditions. G3. Final report and dissemination The principal investigators will prepare reports for USGS as required. In addition, our work will be prepared for presentation at the annual AGU meetings and the peer-reviewed international journal, the Journal of Geophysical Research. This journal is a premier journal in the field of geophysics that reaches a worldwide audience of individuals likely to benefit from this study. G4. Related Efforts
  • 13. 13 Correlations of seismotectonic variables Oncel, Wilson and Nishizawa (2001) document significant spatial variation in the capacity dimension of the active fault complex and b-value throughout Japan. We conducted detailed comparisons of DAF and b along three regional lines that extend along the length of Japan (see lines highlighted in Figure 2). Correlation coefficients between DAF and b were computed at 20km intervals along each line. A local measure of the correlation between b and DAF was computed using a 160km long sliding window. Overall, the correlation between b and DAF is negative, however, examination of the local correlation reveals areas of both positive and negative correlation (see Figure 2 of Oncel and Wilson, 2002). Negative correlations are found to be associated with a drop in b and parallel rise in DAF (see Figure 4 of Oncel and Wilson, 2002). The drop in b suggests increased probability of larger magnitude seismicity. The parallel increase of DAF is associated with denser and more complex regions of the active fault network. We suggest that this occurs because the greater density of faulting in the high DAF areas accommodates rupture on interconnected faults of larger total surface area and therefore larger seismic magnitude. Positive correlations arise from parallel variation of b and DAF. We interpret that the reduced probability of larger magnitude earthquakes results from increased fault density, which allows stress to be released through lower magnitude seismicity on smaller fault strands. Whether the correlation is positive or negative, there is an increase in DAF. However, b will rise or fall depending on the mode of failure within the dense fault systems differs. The differences in the time frames covered by seismicity and active fault data sets have significant effect on our results. The active faults of Japan are considered to be active or potentially active if there has been some movement along the fault during the Quaternary. While rupture may have had a tendency to occur on larger faults within the complex at one period of time, stress release along smaller fault strands may be prevalent at other times. The focus of the work to be undertaken in this research effort will be to conduct a detailed examination of the correlation between seismicity and geodetic strain over similar time frames (100 and 10 year time frames). Temporal variations of b-value vs. DC along the NAFZ in Turkey Our previous work also includes evaluation of the variation between b and DC through time along two major subdivisions of the Northern Anatolian Fault Zone (NAFZ) in Turkey (Figure 1 of Oncel and Wilson, 2002). Here also, a negative correlation was obtained between b and DC through time (Figure 5, and see also Figures 4 and 5 of Oncel and Wilson, 2002). Results obtained over the western part of the NAFZ are weakly negative. Öncel et al. (1995) suggest that the negative correlation in this instance may be an artifact of improved station coverage. The temporal variations of b and DC follow a similar pattern. Increases of b are generally paralleled by decreases of DC. Along the western segment of the NAFZ, which includes Istanbul and the Marmara Sea, b increases from approximately 0.7 to 1.4 over a 43-year period of time extending from 1945 to 1988. The increases of b imply increased event rate or seismic activity with smaller magnitudes, which could arise from the improved coverage during the period of analysis. Öncel et al., (1995) remained cautious in their conclusion and considered the correlation more likely to be an artifact of improved coverage rather than a result of the underlying dynamics. However, if one considers only the data prior to 1965, the correlation is increasingly negative (-0.92, Figure 5, and see also Figure 4 of Oncel and Wilson, 2002). Öncel et al. (1996) undertook a similar comparison of b and DC in the central part of NAFZ (31°-41°E). Along this portion of the NAFZ, the event rate showed no dramatic increase in earthquake frequency due to increased station coverage. The negative correlation between b and DC observed along the central part of NAFZ over a similar time frame (see Figure 5 of Oncel and Wilson, 2002) is also negative (-0.85). The negative correlation between b and DC is significant across the 1100km span of the central and western NAFZ . Seismic activity along the NAFZ has shown a general tendency to migrate westward during the 1900 to 1990 time period (Stein et al., 1997). The decreased level of activity observed in the central portion of the NAFZ, even after improvements in station coverage during the 1965-1975 time period, might be associated
  • 14. 14 with a shift in stress concentration into the western part of the NAFZ. The increased clustering (lower D) and stress accumulation (higher b) along the central NAFZ following 1970 may have been associated with a preparation process for the devastating August 17, 2000 earthquake (MS=7.8, 29.97°E and 40.76°N, Kandilli) and March 13, 1992 (MS=6.8, 39.61°E, 39.71°N) (Oncel and Wilson, 2002). Increased event rate, increased b and decreased DC suggest that the rise in the level of low magnitude seismicity and high intensity clustering along the western portion of NAFZ did not completely release stress transferred into this segment of the fault zone. This combination of factors - westward migration along with increased levels of low magnitude seismicity and higher intensity seismic clustering - are indicators of increased seismic risk in the area. These observations are similar to previous reports that seismic b-value increases after a major earthquake up to a peak value and then decreases to a minimum at the time of occurrence of the next event (e.g., Gibovicz, 1973; Ma, 1978; Smith, 1986, Huang and Turbot, 1988; Main et al., 1990). The occurrence of negative correlation between b and D gives rise to questions whose answers may suggest increased seismic risk. Spatial variations between b-value vs. DC along the NAFZ in Turkey In addition to the temporal variability between b and DC along the NAFZ, spatial variability is also observed (Figure 6, [see also Figure 7a of Oncel and Wilson, 2002]). Öncel et al. (1996) obtained a relation between degree of seismic clustering and mean magnitude in each subdivision along the Anatolian Fault Zone. Öncel et al. (1996) evaluate these differences in detail along the length of the NAFZ and undertake a detailed examination of the spatial variability of seismicity along the NAFZ for seven subdivisions (see Figure 6 of Oncel and Wilson, 2002) each containing the same number of seismic events (n = 100). This analysis is restricted to the NAFZ and regions 1 through 7 extend from west to east along its length. The variability between b and DC along the fault zone provides a continuous view of the divergence between b and DC that occurs in the central NAFZ. The spatial variations yield a strong negative correlation (r=-0.85) between b and DC (see Figure 10 c of Oncel et al., 1996). High b is considered to be indicative of low stress build up accompanied by continued stress release in the form of numerous small magnitude earthquakes, whereas low b is associated with areas where stress builds up over time and is released by less-frequent larger magnitude earthquakes. Lower DC is associated with dense epicenter distributions and higher intensity clustering while high DC regions are associated with less dense epicenter distributions and a tendency to be less clustered. The result implies strong negative correlation between stress concentration (b value) and seismic clustering (Dc). The spatial pattern becomes negative in response to an increase in stress concentration (lower b) and weaker clustering (higher DC) through the convex-upward bend occurring in the central part of the NAFZ (Figure 6 [see alsoFigure 7a of Oncel and Wilson, 2002]). Increased clustering (lower DC) and a tendency to experience smaller magnitude seismicity (higher b) characterize both ends of the NAFZ. It is apparently in these regions where the NAFZ interacts with crosscutting fault systems that stress is more easily dissipated in the form of larger numbers of smaller magnitude earthquakes (i.e. higher b). The spatial variation of b and DC reveals a change in the dynamics of plate interaction along the length of NAFZ. However, the significance of those changes is not clearly understood. The areas of higher b and lower DC (more clustered seismicity) may be the result of creeping parts of fault zone. Whereas higher DC (less clustered seismicity) and lower b may be related to asperities along the fault (Öncel and Wyss, 2000). Seismotectonic Evaluations The relationships of the Gutenberg-Richter b-value to patterns of faulting and seismicity along convergent and transform plate boundaries provides information about the dynamics of plate interactions. In Japan, the comparison identifies differences in the way in which stress is released within complex fault systems. In areas of positive correlation between b and D0 the increased complexity and fragmentation of the fault system (increased D0) provides an abundance of small fault strands along which stress can be released through more frequent but lower magnitude earthquakes (increased b). In areas of increased complexity in the active fault system (higher D0) associated with larger magnitude seismicity (lower b) stress release occurs on fault planes of larger surface area.
  • 15. 15 In Turkey, the comparisons of b and DC (correlation dimension of epicenter distribution) were followed through time and space along the length of the NAFZ. Temporal variations of b and DC, in general, are negatively correlated. There is a significant trend through time for b to increase while DC decreases (see figures 4 and 5 of Oncel and Wilson, 2002). Spatial variation in the patterns of seismicity along the NAFZ reveals presence of strong divergence in b and DC through the central convex northward bend in the NAFZ as noted above. DC increases and b decreases through this area leading to negative correlation between b and DC. Difference between DC and b in the central part of the NAFZ decreased through time. However, from 1960 to 1975, the difference is 45% less than it was through much of the preceding 25 years. In the western part of the NAFZ there is a similar decrease in DC (increased seismic clustering) followed by increases of b prior to 1965 (see Figure 4a of Oncel and Wilson, 2002). Improved station coverage from 1965 to 1975 interrupts this trend (see Figure 4a of Oncel and Wilson, 2002), and by 1975, b drops from 1.1 to 0.7. This drop is very significant given the increased density of monitoring in the area. The drop in b suggests that there was a build-up of stress in the western portions of the NAFZ, which was being released in the form of larger magnitude seismicity for a short time interval. Following that brief period, the correlation of DC to b became positive. The recent trend (1975-1988) is for parallel increases between b and DC (r = 0.48) (Figure 5 [see also Figure 4c of Oncel and Wilson, 2002]). The earlier period of negative correlation (1945-1965) might imply that seismicity was de-clustered and distributed along large fault strands. The recent positive trend covers a relatively short time interval but reveals behavior, which is significantly different from the preceding 30 year time period. From 1975 - 1988, the tendency has been for seismicity to be less clustered (DC rising) and to consist of more frequent but smaller magnitude earthquake activity. The variations of b and DC through time are unusual. Their significance in relation to the recent earthquakes in the area is unclear. Did the period of positive correlation between b and DC in the central NAFZ (1960 to 1975) transfer stresses into the western NAFZ causing a short increase in DC and decrease in b? Was the increased probability of high magnitude seismicity actually accommodated by strain release? Was the following period of increased low level de- clustered seismicity inadequate to reduce the build up of stress that was occurring in the western NAFZ. The recent earthquakes in that area suggest that it was not. Some of the differences noted above between the central and western segments of the NAFZ may be related to differences in the mode of failure as indicated by earthquake focal mechanisms as much as more densely spaced geodetic studies (McClusky et al., 2000, Straub and Kahle, 1995 and 1997). The process of creep is usually associated with higher b, whereas asperities are often associated with lower b-value (Oncel and Wyss, 2000). Along the eastern and central parts of the NAFZ, failure occurs under compression, whereas along its western extent, failure occurs through extension in Aegean region. The outgrowths of our ongoing research reveal interesting seismotectonic relationships. These observations force us to ask new questions and to seek a better understanding of the processes involved. The behavior we see in many instances appears anomalous as suggested by those changes preceding the devastating earthquakes in western Turkey during 1999. Continued observation of these processes may help us gain better insights into the processes at work and their potential for helping us identify potentially hazardous associations. References Cited Aki, K., Maximum likelihood estimate of b in the formula log N = a - bm and its confidence limits, Bull. Earthquake Res. Inst., Tokyo Univ., 43, 237-239, 1965. Aki, K., 1967, Scaling law of seismic spectrum: Journal of Geophysical Research, vol. 72, p. 1217-1231. Barbano, MS, De Rubeis V, Tosi P, Vinciguerra S, 2000, Clustering properties of Etna seismicity during 1981-1991, J. Seism. 4: (2) 191-196 . Davy, P., Sornette, A., Sornette, D, 1992, experimental discovery of scaling laws relating fractal dimensions and length distribution exponent of fault systems, Geophys. Res. Lett., 4, 361-363.
  • 16. 16 De Rubeis, V., Dimitriu, P., Papadimitriou, and Tosi, P., 1993, Recurrent patterns in the spatial behavior of Italian seismicity revealed by the fractal approach, Geophys. Res. Lett., 18, 1911-1914. Geographical Survey Institute of Japan, 1997, Horizontal Crustal Strain Map, 1:2,000,000: Geographical Survey Institute of Japan, Tsukuba, Ibaraki Prefecture, http://cais.gsi-mc.go.jp/HIZUMI/hizumi.html. Gibowicz, S., Lasocki, S., 2001, Seismicity induced by mining: Ten years later, Advances in Geophysics, 44, 39-181. Gutscher, MA., and Lallemand, S., 1999. Birth of a major strike-slip fault in SW Japan, TERRA NOVA, 11: (5) 203-209. Godano, C., Caruso, V., 1995, Multifractal analysis of earthquake catalogs, Geophys. J. Int., 121: (2) 385- 392. Godano C, Tosi P, Derubeis V, et al., 1999, Scaling properties of the spatio-temporal distribution of earthquakes: a multifractal approach applied to a Californian catalogue, Geophys. J. Int. 136: (1) 99- 108. Eneva, M., 1996, Effect of limited data sets in evaluating the scaling properties of spatially distributed data: an example from mining-induced seismic activity, Geophys, J. Int., v. 124: 773-786 Hashimoto, M., Miyazaki, S., and Jackson, DD., 2000, A block-fault model for deformation of the Japanese Islands derived from continuous GPS observation, Earth Planet and Space, 52: (11) 1095- 1100. Feng, X., and Seto, M., 1999. Fractal structure of the time distribution of microfracturing in rocks, Geophys. J. Int., 136, 275-285. Ikami, A., Yoshii, T., Kubota, S., Sasaki, Y., Hasemi, A., Moriya, T., Miyamachi, H., Matsu'ura, R., and Wada, K. (1986) A seismic refraction profile in and around Nagano Prefecture, central Japan: Jour. Phys. Earth, v. 34, p. 457-474. Isozaki, Y., 1996, Anatomy and genesis of a subduction related orogen: A new view of geotectonic subdivision and evolution of the Japanese islands; in The Island Arc, vol. 5, pp. 289-320. Jackson, D.D., and Y.Y. Kagan, Testable earthquake forecasts for 1999, Seism. Res. Lett., 70, 393-403, 1999. Kano, K. and Wakita, K., 1992, A geological synthesis of the Japanese Islands: International Geological Congress, Presentation and Abstracts with Programs. Kijko, A., Öncel, A.O., 2000. Probabilistic Seismic Hazard Maps for Japanese Islands, Journal of Soil Dynamics and Earthquake Engineering-Wessex Institute of Technology, 20, 485-491. Kikuchi, M., and H. Kanamori., 1996, Rupture process of the Kobe, Japan, earthquake of Jan. 17, 1995, determined from teleseismic body waves, J. Phys.Earth, 44, pp. 429-436. Lu, CS., Harte, D., and Bebbington, M, 1999, A linked stress release model for historical Japanese earthquakes: coupling among major seismic regions, Earth. Planets and Space, 51: (9) 907-916. Main, I. G., 1992, Damage Mechanics with long-range interactions: correlation between the seismic b- value and the fractal two-point correlation dimension: Geophys, J. Int., v. 111: 531-541 Main, I.G., 1996, Statistical physics, seismogenesis, and seismic hazard, Reviews of Geophys., 34, 433- 462. Mark W. Stirling and Steven G. Wesnousky, 1998, Comparison of Recent Probabilistic Seismic Hazard Maps for Southern California Bulletin of the Seismological Society of America Volume 88 - Number 3 - June 1998 Nakamura, K., 1983, Possible nascent trench along the Japan Sea as the convergent boundary between the Eurasian and North American plates: Bulletin of the Earthquake Research Institute, vol. 58, p. 711- 722. Pyrak-Nolte L.J, Myer, L.R., Nolte, D.D., 1992, Fractures : Finite-size scaling and multifractals, Pure. Appl. Geophys., 138,679-705. Okumura, K., Shimokawa, K., Yamazaki, H., and Tsukuda, E., 1994, Recent surface faulting events along the middle section of the Itoigawa-Shizuoka Tectonic Line - trench Survey of the Gofukuji fault near Matsumoto, central Japan: Zisin (The Journal of the Seismological Society of Japan), Ser. 2, 46, 425- 438.
  • 17. 17 Okumura, K., 1997,Rupture history and segmentation of the Itoigawa-Shizuoka Tectonic Line active fault system: Geological Survey of Japan Information Sheet S-6, 4p. Öncel, A.O., Wilson, T., 2002. Space-Time Correlations of Seismotectonic Parameters and examples from Japan and Turkey Preceding the Izmit Earthquake, Bulletin Seismological Society of America, 92, 339-350. Oncel, A. O., Wilson, T. Correlation of seismotectonical variables and microplate velocity field in western Turkey and the eastern Mediterranean, Submitted to Bulletin Seismological Society of America. Oncel, A. O., Wilson, T., Nishizawa, O., 2001, Size scaling relationships in the active fault networks of Japan and their correlation with Gutenberg-Richter b values, J. Geophys. Res.,in press. Öncel, A. O., Wyss, M., 2000b, The major asperities of the 1999 M7.4 Izmit earthquake, defined by the microseismicity of the two decades before it, Journal of Geophysical Research, Geophys. J. Int., 143, 501-506. Öncel, A.O. and M. Wyss., 2000b. Mapping the major asperities by minima of local recurrence time before the 1999 M7.4 Izmit earthquake, Book on Izmit earthquake, pp. 1-4, The Izmit and Duzce Earthquakes: preliminary results, Editors: Aykut Barka, Ozgür Kozacı, Serdar Akyüz and Erhan Altunel, Publisher: Istanbul Technical University, ISBN: 975- 561-182-7. Öncel, A. O., I. Main., Ö, Alptekin, and P. Cowie, 1996, Spatial variations of the fractal properties of seismicity in the Anatolian fault zones, Tectonophysics, 257, 189-202. Öncel,A. O., I. Main,I., Ö. Alptekin,P. Cowie, 1996, Temporal variations of the fractal properties of seismicity in the north Anatolian fault zone between 31°E and 41°E, Pure Appl. Geophy. 146, 147- 159. Öncel,A.O., Ö. Alptekin, I. Main, 1995.Temporal variations of the fractal properties of seismicity in the western part of the north Anatolian fault zone: Possible artifacts due to improvements in station coverage, Nonlinear Processes Geophys., 2, 147-157. Redner, S., 1990, Random multiplicative processes: An elementary tutorial, Am. J. Phys. 58, 267-273. Scholz, C.H., N.H. Dawers, J-Z. Yu, M.H. Anders and P.A. Cowie, 1993, Fault growth and scaling laws: preliminary results: Journal of Geophysical Research, 98(B12):21,951-21,962. Scholz, C. H., 1995, Fractal transitions on geological surfaces: in Fractals in the Earth Sciences, C. C. Barton and P. LaPointe, Editors, Plenum Press, New York, 131-140. Scholz, C.H., 2000, Evidence for a strong San Andreas fault, Geology, 28:163-166. Scholz, C.H., 1990, The Mechanics of Earthquakes and Faulting, Cambridge University Press, 439 pp. Shimokawa, K., 1997, Research on earthquake potential assessment around the eastern margin of the Japan Sea: Geological Survey of Japan Information Sheet S-4, 4p. Smith, W. D., 1986, Evidence for precursory changes in the frequency-magnitude b value, Geophys. J. R.Astron. Soc. 86, 815-838. Tadokoro, K., Ando, M., and Umeda, Y., 1999, S wave splitting in the aftershock region of the 1995 Hyogo-ken Nanbu earthquake, vol. 104, p. 981-991. Takahashi, M., and Nomura, S., 1989, Paleomagnetism of the Chichibu quartz diorite - Constraints on the time of lateral bending of the Kanto Syntaxis: Journal of Geomagnetism and Geoelectricity, vol. 41, p 479-489. Toda, S., Katoh, S., Kobayashi, F., Kagawa, T., Yokota, H., Nakagawa, K., Takamura, K., and Okada, A., Seismic Reflection Survey across the Central Part of the Arima-Takatsuki Tectonic Line, Kinki District, Central Japan: Nature and Human Resources, vol. 3, p9-21. Tsukuda, E., 1997, Geologic structure at the Bando observation well, Naruto, Tokushima: Geological Survey of Japan Information Sheet S-5, 4p. Wakita, K., 1997, The geology of Japan: A guide for the CD-Rom "Digital Geologic Map of East and Southeast Asia"; CCOP Technical Bulletin, Vol. 26, p.47-57. Xie, H., 1992, Fractals in rock mechanics, A.A. Balkema, Rotterdam. Xu YB, Burton PW, 1999. Spatial fractal evolutions and hierarchies for microearthquakes in central Greece , Pure. Appl. Geophys ,154: 73-99.
  • 18. 18 Wilson, T., and Kato, H., 1992, Interpretation of the Matsumoto Basin gravity low: in Bulletin of Geological Survey of Japan. Special Issue - Cenozoic geohistory and tectonics in Japan, vol. 43, no. 1/2 p. 31-42. Wilson, T., and Kato, H.,1995, Gravity model studies of the northern Fossa Magna: Central Honshu, Japan. Bulletin of the Geological Survey of Japan. Vol. 46, no. 1, p 1-22. Wiemer, S., and Wyss, M., 2000, Minumum magnitude of completeness in earthquake catalogs: Examples from Alaska, the western United States, and Japan, Bull. Seism. Soc. Am., pp. 859-869. Wyss, M., D. Schorlemmer, and S. Wiemer, Mapping asperities by minima of local recurrence time: The San Jacinto-Elsinore fault zones, J. Geophys. Res., 105, 7829-7844, 2000. Wyss, M., Hasegawa, A. and Nakajima, J., 2000a. Source and path of magma for volcanoes in the subduction zone of northeastern Japan. Geophysical Research Letters: submitted. Wyss, M., Schorlemmer, D. and Wiemer, S., 2000b. Mapping asperities by minima of local recurrence time: The San Jacinto-Elsinore fault zones. Journal of Geophysical Research, 105: 7829-7844. Wyss, M., 2002. Locked and creeping patches along the Hayward fault, California, Geophys. Res. Lett., in press. Yokokura, T., Kano, N., Yamaguchi, K., and Miyazaki, T., 1997, Faults and basement structures around the epicentral region of the 1995 Hyogo-ken Nanbu earthquake derived from seismic reflection profiling: Geological Survey of Japan Information Sheet S-2, 2p. Yokokura, T., 1999, Seismic investigation of an active fault off Kobe: Another disaster in the making: Leading Edge, vol. 16, no. 12, p. 1417-1421. G5. Project personnel and bibliography of directly related work Ali O. Oncel Educational Background: 1989 BSc- Geophysics, Istanbul University, 1992 MSc-Geophysics, Istanbul University, 1996 Ph.D-Geophysics, Istanbul University, 2000 Associate Professor of Seismology, Turkish Higher Education Professional Background: 2001 -present Geological Survey of Canada-National Earthquake Hazards Program 1998 - 1999 Geological Survey of Japan/Tsukuba- Post Doctoral Research Fellow 1994 - 1995 International Center for Theoretical Physics/Trieste –Research Fellow 1993 - 1994 Edinburgh University –Guest Researcher 1990 - 2000 Istanbul University- Researcher 2000 - 2001 Istanbul University-Associate Professor Research/Management Experience Examples of previous research grants include:  Microseismicity of Marmara Sea and Seismic Hazard, 1038-250897, 40 pp, completed, supported by Research Foundation of Istanbul University. Recent Related Publications 1. Oncel, A.O., Wilson, T., 2002. Correlation of seismotectonic variables and microplate velocity in western Turkey and the Eastern Mediterranean, Bulletin Seismological Society of America, submitted. 2. Öncel, A.O., Wilson, T., 2002. Space-Time Correlations of Seismotectonic Parameters and examples from Japan and Turkey Preceding the Izmit Earthquake, Bulletin Seismological Society of America, 92, 339-350. 3. Öncel, A.O., Wyss, M., 2000. The major asperities of the 1999 M7.4 Izmit earthquake, defined by the microseismicity of the two decades before it, Geophysical Journal International-OXFORD.,143, 501-506.
  • 19. 19 4. Öncel, A.O., Wilson, T., Nishizawa, O.,2001. Size Scaling Relations in the Active Fault Networks of Japan and their correlation with Gutenberg-Richter b-Values, Journal of Geophysical Research-American Geophysical Union,106, 21,827-21,841. 5. Kijko, A., Öncel, A.O., 2000. Probabilistic Seismic Hazard Maps for Japanese Islands, Journal of Soil Dynamics and Earthquake Engineering-Wessex Institute of Technology, 20, 485-491. G6. Institutional qualifications The Department of Geology and Geography's geophysics lab provides access to a variety of modeling and interpretation software including Interpex Ltd.'s gravity, magnetics, resistivity, induced polarization and terrain conductivity modeling software; Eikon Technologies EMigma EM modeling software; GM-Sys garvity and magnetic modeling software; network access to GeoGraphix's SeisVision and their suite of GMA Plus and Seismic MircoTechnology’s Kingdom Suite seismic analysis software. seismic products. We also have network access to GeoGraphix's GES Explorer and Prizm software. The department also has considerable GIS and Remote sensing resources (ENVI, MicroImages TNT, ArcView and ArcInfo). In addition, students have access to a 12 - channel engineering seismograph, VLF and terrain conductivity meters, and a magnetometer. Section plotters, scanners and digitizer tablets are available in student research areas. A large-format plotter is also available in the geophysics laboratory, The majority of the research conducted under this grant by WVU will be undertaken on Dr. Wilson's office computer and will use resources in the adjacent geophysics lab. For data sources, refer to discussion at the top of page 8. Additional information relevant to the strain data will be obtained if needed from Dr. Kumaki Yohta, Head, Research Planning Division Geographical Survey Institute e-mail: kumaki@surv.gsi.go.jp. West Virginia maintains substantial library facilities on both of its Morgantown campuses. G7. Project management plan The Geological Survey of Canada Task Summary - Seismotectonic Analysis (Principal Investigator: Dr. Ali Oncel) - See collaborative submission from Dr. Oncel of the Canadian Geological Survey – A brief list of activities to be undertaken by Dr. Oncel includes: 1. compilation of instrumental Japanese earthquake catalogue from the Japan Meterological Agency (JMA) data file for the time period between 1926 and 2002(October 1-15 of 2002). 2. compilation of historical Japanese earthquake catalogue from the data files of Utsu [1982] and Usami [1996] (October 16-30 of 2002). 3. compilation of instrumental and historical catalogues considering the temporal changes of magnitude(November 1-15 of 2002). 4. declustering the secondary events to obtain a homogenous catalogue (November 16-30 of 2002). 5. compute the seismic b-value and a-value for different time intervals of 10 year (1985-1994) and 100 years (1883-1994) (December of 2002). 6. computation TL values for different target magnitudes (Mtarget) (January 1 to June 15th of 2002) 7. computation fractal dimensions for different q (=2 and 15) in order to extreme limits of seismic clustering (January 15 to June 30th of 2002), 8. present preliminary results at Spring EGU meeting 9. continued for different tectonic origins of spatial variability of seismotectonic variables, May 15th through June 30th of 2003 10. write JGR paper and final report (August 15th through September 30th of 2003). Expenditures during the first 4 months of the project are required for purchase of the PC and supplies relate to our research undertaking. Dr. Oncel's time during the working year will be cost-shared by
  • 20. 20 Geological Survey of Canada. Salary expenditures under the grant are not required until the summer of 2003 at which time (May 15th through June 30th , Dr. Oncel will work full time on the project. WVU Task summary and timetable 1) compilation of geodetic strain data from the Geographical Survey Institute of Japan's crustal strain database (October to November of 2002). 2) organization of the databases for preliminary comparison of b-value to strain (November of 2002) 3) preliminary comparisons of b-value and strain (October to November of 2002). 4) interpretation of multifractal response computed by Dr. Oncel for scale transitions (Jan. 2003 to May 15th 2003) 5) complete evaluation of correlations between a and b value, fractal dimensions and various geodetic strain measurements, at regional and local scales (January to June 30th of 2002) 6) present preliminary results at Spring AGU meeting 7) continued evaluation and interpretation of possible tectonic origins of spatial variability observed in the correlation between seismotectonic variables May 15th through June 30th of 2003 8) interpretation of the potential significance of variable spatial correlation as a seismic hazard indicator. (June 1st to June 30th of 2003) 9) write JGR paper and final report (August 15th through September 30th of 2003). Expenditures during the first 8 months of the project are required for purchase of the PC and supplies relate to our research undertaking. Dr. Wilson's time during the academic year will be cost-shared by West Virginia University. Salary expenditures under the grant are not required until the summer of 2003 at which time (May 15th through June 30th , Dr. Wilson will work full time on the project. G8. Current Support and pending applications Wilson - Current Support: Oak Ridge Fellowship remote sensing and geophysical studies over a pilot carbon sequestration site for DOE NETL (summer 2002). This effort will overlap the time-period for the proposed USGS research effort during the fall and winter of 2002-2003. Pending support: Faculty Fellowship with Pacific Northwest National Labs. This activity will take place during the summer of 2002. Continuation into 2003 is possible, but activities would be scheduled so as not to conflict with the time frame of this proposed USGS activity. G9. Continuation projects Wilson - is currently involved in conducting remote sensing and geophysical studies over a pilot carbon sequestration site with the Department of Energy’s National Energy Technology Lab. This work was continued following last summer’s ORISE faculty fellowship appointment with NETL.
  • 21. 21 Figure 1: Regional tectonic setting of Japan (taken from Kano and Wakita, 1992).
  • 22. 22 -400 -200 0 200 400 kilometers -200 0 200 400 600 800 kilometers -5 -3 -1 1 3 5 Strain Difference 10year strain - 110 year strain/11 Figure 2: A comparison of relative strain rates over the recent 1985-1994 time period is made to those occurring since 1885. Area strain over the 110 year period was divided by11 (yielding an average strain rate per 10 year interval) and then subtracted from the area strains observed over the recent 10 year time-frame. 39.00 40.00 41.00 42.00 9 23.00 24.00 25.00 26.00 27.00 28.00 29.00 30.00 40.00 12 3 4 9 8 7 6 5 20 nstrain/yr 200nstrain/yr 18.5 mm/yr a=3.8 b=1.51 15 nstrain/yr 240nstrain/yr 16.5 mm/yr a=2.9 b=1.39 5nstrain/yr 75 nstrain/yr 12.9 mm/yr a=1.6 b=1.47 30nstrain/yr 190nstrain/yr 11 mm/yr a=2.6 b=1.11 b=1.75 a=4.0 23.9 mm/yr 40 nstrain/yr 30 nstrain/yr b=1.81 a=4.9 21.9 mm/yr 60 nstrain/yr 25 nstrain/yr b=1.24 a=3.1 23.5 mm/yr 70 nstrain/yr 50 nstrain/yr b=1.16 a=3.1 23.8 mm/yr 220 nstrain/yr 10 nstrain/yr b=0.97 a=2.7 15 mm/yr 8 nstrain/yr 170 nstrain/yr Figure 3: Seismic zones along the NAFZ are located on the above map. Gutenberg- Richter a- and b-values along with the average plate velocity calculated in each of these zones are noted.
  • 23. 23 Figure 4. : Generalized-correlation-integral functions derived from epicenter distributions in seismic zone 1 (see Figure 1) in the eastern part of Marmara region which includes the recent (1999) Izmit earthquake. Fractal plots associated with q-values of 2 and 15 are labeled for reference. D15 D2 15 1.10 14 1.11 13 1.11 12 1.12 11 1.12 10 1.13 9 1.14 8 1.16 7 1.18 6 1.20 5 1.23 4 1.27 3 1.34 2 1.44 q Dq Multiple Fractal N=3912 q=2-15 DISTANCE R (KM) CORRELATIONINTEGRALC(R>r)
  • 24. 24 1976-1988 1.1 1.2 1.3 1.4 b 0.6 0.7 0.8 0.9 1.0 1.1 1.2 Dc 0.7 0.8 0.9 1.0 b 1.1 1.2 1.3 1.4 DC 1945-1965 r = -0.92 r = 0.48 b-value DC 1940 1950 1970 1980 19901960 Year 0.6 0.8 1.0 1.2 1.4 1.6 DC and b Figure 5: Correlation between variations in b and DC in the western NAFZ (A) are examined over the 1945-1965 (B) and 1976-1988 (C) time periods.
  • 25. 25 K 1999 Mw=7.4 2.0 1.6 1.2 0.8 0.4 0.0 b value DC 1 2 6 5 4 3 7 Lateral Distance (n=100) 24.00 26.00 28.00 30.00 32.00 34.00 36.00 38.00 40.00 42.00 44.00 38.00 40.00 42.00 38.00 40.00 42.00 2.0 1.6 1.2 0.8 0.4 0.0 Figure 6. Areas 1 through 7 along the NAFZ are bounded along strike by a line of longitude. The size of each region is adjusted to include one hundred earthquakes. Seismicity in the wider areas is less clustered in distribution. The wider areas of less clustered seismicity are associated with higher D (less clustered) and lower b (greater likelihood of larger magnitude earthquake).