Environmental monitoring of         soil radon in a very tectonic          area in South West Greece               A. A. F...
Objectives Investigation of the usefulness of measuring soil  radon gas anomalies in a very active tectonic area in  Sout...
Introduction Radon (222Rn) is a naturally occurring  radioactive noble gas. The presence of radon in  the environment is ...
Seismicity in South West Greece 1/2 The study area of Ilia is  located in South West Greece  and is dominated by  extensi...
Seismicity in South West Greece 2/2 Ilia is a part of a broad neotectonic  depression structure which is very close to  t...
Materials & MethodsInstrumentation (Active Technique)                     • Soil gas is pumped at the                     ...
Materials & methods              spectral fractal analysis During the complex process of earthquake preparation, linkages...
Background noise presents Scalogram of the DWT      0<b(t)<1, moving from the the firstof the 2008 radon signal   stage of...
Application of the Discrete Wavelet Transform                                      Radon concentration                    ...
Material & Methods             Environmental Parameters It has been shown that the anomalies  of soil radon concentration...
Material & Methods                                      Asperity Model From the various theoretical explanations of  the ...
Conclusions The radon anomalies can give evidence about tectonic  disturbances in the Earth’s crust, though the radon cha...
References   UNSCEAR, United Nations Scientific Committee on the Effects of Atomic Radiation, 2000. Sources and Effects o...
http://env-hum-comp-res.teipir.gr/
Upcoming SlideShare
Loading in …5
×

Environmental monitoring of soil radon in a very tectonic area in south west Greece

591 views
490 views

Published on

Abstract

This paper focuses on the investigation of the usefulness of measuring soil radon as a trace gas in the search of earthquake precursors. A multilevel approach was followed: (a) Detailed preparatory experimentation. (b) Set-up of methods and devices. (c) Active and passive radon measurements during a very active tectonic period in Peloponnese (Greece) on 2008. This period was combined with the occurrence of two very destructive earthquakes. (d) Detailed discussion and analysis of significant collected radon signals that included two very strong radon anomalies prior to the 8/6/2008 M=6.5 earthquake which occurred 29 km from the measuring site. The two detected strong radon disturbances could be possibly related only to the 8/6/2008 earthquake. (e) Discussion on the interpretation of the detected radon anomalies. The recent (2008) asperity model is proposed as a possible explanation of these anomalies. The paper concluded that the strong radon disturbances may be linked to strong earthquakes.

0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total views
591
On SlideShare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
5
Comments
0
Likes
0
Embeds 0
No embeds

No notes for slide

Environmental monitoring of soil radon in a very tectonic area in south west Greece

  1. 1. Environmental monitoring of soil radon in a very tectonic area in South West Greece A. A. Fotopoulosb, E. Petrakia, E. M. Vlamakisb, X. A. Argyrioub, N. N. Chatzisavvasb, T. J. Sevvosb, A. Zisosc, C. Nomicosd, A. Louizie, J. Stonhama, P. H. Yannakopoulosb, D. Nikolopoulosc aBrunel University, Dept. of Engineering and Design, UK b Department of Computer Systems Engineering, Technological Educational Institute (TEI) of Piraeus, Greece c Department of Physics, Chemistry and Material Science, Technological Educational Institute (TEI) of Piraeus, Greece d Department of Electronics, Technological Educational Institution of Athens, Greece e Medical Physics Department, Medical School, University of Athens, Greecehttp://env-hum-comp-res.teipir.gr International Scientific Conference eRA-7
  2. 2. Objectives Investigation of the usefulness of measuring soil radon gas anomalies in a very active tectonic area in South West Greece and possible linkage to earthquakes Set up of radon monitoring station International Scientific Conference eRA-7
  3. 3. Introduction Radon (222Rn) is a naturally occurring radioactive noble gas. The presence of radon in the environment is in rocks, soil, building materials, underground and surface waters (UNSCEAR 2000). Radon Measurement Earth Crust The stress–strain developed within the earths crust before an earthquake opens up various pathways and leads to changes in gas transportation from deep earth to surface (Thomas, 1988). Anomalies of radon concentrations impending pre-earthquakes periods have been observed in groundwater, thermal waters and soil gas (Erees et al., 2007; Choubey et al., 2009; Cicerone et al., 2009; Ghosh et al., 2009). The above issues clearly indicate that radon monitoring in soil could be very important from geological point of view. Schematic cross section of the in groundwater basin (Ulomov and Mavashev, 1971). International Scientific Conference eRA-7
  4. 4. Seismicity in South West Greece 1/2 The study area of Ilia is located in South West Greece and is dominated by extensional seismicity structures. These structures evoked more than 600 earthquakes of ML>4.0 in the last century (http://labtect.geol.uoa.gr/pa ges/fountoulis/esismol.htm). International Scientific Conference eRA-7
  5. 5. Seismicity in South West Greece 2/2 Ilia is a part of a broad neotectonic depression structure which is very close to the convergent boundary between the African and the European tectonic plates and it’s close to the western part of the Hellenic Trench. A station for the surveillance of soil radon has been installed in Kardamas (Peloponnese, Ilia Prefecture, South West Greece). Prior research has shown that both active(Alpha Guard Unit) & passive techniques (Solid State Nuclear Track Detectors) can be used for the measurement of Soil Radon gas, with active techniques to be more precise and quick (Nikolopoulos et. al., 2009). International Scientific Conference eRA-7
  6. 6. Materials & MethodsInstrumentation (Active Technique) • Soil gas is pumped at the maximum available rate of 1 L/min to maximize the quantity of the pumped gas and to enhance the detection efficiency. • Radon was measured at the rate of 1 measurement per 1 min(Nikolopoulos et al., 2012). • Atmospheric pressure (AP), relative humidity (RH) and DATA temperature (T) are continuously LOGGER monitored as well. International Scientific Conference eRA-7
  7. 7. Materials & methods spectral fractal analysis During the complex process of earthquake preparation, linkages between space and time produce characteristic fractal structures (Smirnova and Hayakawa, 2007; Hayakawa and Hobara, 2010; Eftaxias, 2010; Kapiris et. al., 2002; Contoyiannis et. al.,2005) Power spectrum directly reflects the physical scales of the processes that affect structure formation (Kapiris et al., 2003) If the recorded time-series A(ti) is a temporal fractal then a power law spectrum is expected, 𝑺 (𝒇 ) = 𝒂 ⋅ 𝒇−𝒃 where f is the frequency of the transform, 𝑆 𝑓 the power spectral density and b the linear spectral slope. Spectral scaling exponent is a measure of the strength of time correlations. International Scientific Conference eRA-7
  8. 8. Background noise presents Scalogram of the DWT 0<b(t)<1, moving from the the firstof the 2008 radon signal stage of general disorder to the final stage of the earthquake presenting stability and low self- organisement. For the power law spectrum 𝑺 (𝒇 )=𝒂⋅𝒇−𝒃 • The area between the two radon spikes is very critical and presents Time evolution of the fractal behaviour (b values above 1,5) power-law-beta values • This low frequency enhancement reveals the predominance of the larger fracture events which is considered as a footprint of the preparation of earthquakes (Eftaxias et al.,2009) Anomalies detected in radon concentrations in 2008 3 & 2 Levels of soil radon months before 6,5 Earthquake ofconcentration in 2008 6/8/2008 International Scientific Conference eRA-7
  9. 9. Application of the Discrete Wavelet Transform Radon concentration during the five-day disturbance of the first radon spike in 2008 Log-log diagram of S(f)=af-b versus frequency. The enhancement of low frequencies (low negative logarithms) are superimposed on the Power Spectrum Density, the log-log slope is reduced and, subsequently, the calculated power-law b- value and the Spearman correlation coefficient. International Scientific Conference eRA-7
  10. 10. Material & Methods Environmental Parameters It has been shown that the anomalies of soil radon concentration presented non-significant cross-correlation with the measured environmental parameters: i) temperature ii) air- pressure iii) relative humidity & iv) precipitation. (Nikolopoulos et. al., 2012) International Scientific Conference eRA-7
  11. 11. Material & Methods Asperity Model From the various theoretical explanations of the Radon anomalies the asperity model STAGE 1 (Eftaxias et al.,2008) tend to be the predominant method (Petraki et. al., 2012)The fracture of the When the STAGE 2 heterogeneous electromagneticsystem in the focal anomalies arearea obstructs the emitted the “siege” backbone of of the strong asperities. asperities begins. Cracking will occur in strong asperities IF local stress exceeds their fracture stress At this stage, critical The anomalous radon emissions of the 2008 signal, could be anti-persistent MHz attributed to the first stage of the model, i.e., the phase in electromagnetic which the fracture of the strongly heterogeneous medium anomalies occur. obstructs the asperities backbone (Petraki et. al., 2012) International Scientific Conference eRA-7
  12. 12. Conclusions The radon anomalies can give evidence about tectonic disturbances in the Earth’s crust, though the radon changes The study area in South West Greece presented in radon time- series very peculiar disorders in 2008 (Nikolopoulos et al., 2012) The radon geophysical monitoring station revealed particuraly interesting data in a significant period before the catastrofic event The cross-correlation of radon anomalies as an earthquake precursor have to be further analyzed with multivariate statistics in order to strengthened the theory of close interconnection. International Scientific Conference eRA-7
  13. 13. References UNSCEAR, United Nations Scientific Committee on the Effects of Atomic Radiation, 2000. Sources and Effects of Ionizing Radiation. UNSCEAR 2000 Report to the General Assembly with Scientific Annexes, United Nations, New York. Nazaroff, W.W, Nero A.V., 1988. Radon and its Decay Products in Indoor Air. John Wiley & Sons, Inc., USA. ISBN 0-471-62810-7, 518 pp. Planinic´ J. , Radolic´ V. , Lazanin Z ., Temporal variations of radon in soil related to earthquakes, App Rad Isotop (2001) 55, 267-272 Nikolopoulos, D., Petraki, E., Marousaki, A., Potirakis, S.M., Koulouras, G., Nomicos ,C., Panagiotaras, D., Stonham, J., Louizi, A., 2012. Environmental monitoring of radon in soil during a very seismically active period occurred in South West Greece. J. Environ. Monit.14, 564-578 Rikitake, T., 1987. Earthquake precursors in Japan: precursor time and detectability. Tectonophysics 136(3–4), 265–282 Cicerone, R.D., Ebel, J.E., Britton, J., 2009. A systematic compilation of earthquake precursors. Tectonophysics. 476, 371-396. D. Mazur, M. Janik, P. Loskiewicz, P. Olko and J. Swankon, Measurements of radon concentration in soil gas by CR-39 detectors, Radiat. Meas., 1999, 31, 295-300. Eftaxias, K., Balasis, G., Contoyiannis, Y., Papadimitriou, C., Kalimeri, M., Athanasopoulou, L., Nikolopoulos, S., Kopanas, J. , Antonopoulos, G., Nomicos, C., 2010. Unfolding the procedure of characterizing recorded ultra low frequency, kHZ and MHz electromagnetic anomalies prior to the L’Aquila earthquake as pre-seismic ones – Part 2. Nat. Hazard. Earth Sys. 10, 275–94. Eftaxias, K., Balasis, G., Contoyiannis, Y., Papadimitriou, C., Kalimeri, M., Athanasopoulou, L., Nikolopoulos, S., Kopanas, J. , Antonopoulos, G., Nomicos, C., 2009. Unfolding the procedure of characterizing recorded ultra low frequency, kHZ and MHz electromagnetic anomalies prior to the L’Aquila earthquake as pre-seismic ones – Part 1, Nat. Hazard. Earth Sys. 9, 1953–1971. Hayakawa, M., Hobara, Y., 2010. Current status of seismo-electromagnetics for short-term earthquake prediction. Geomatics, Natural Hazards and Risk 1(2), 115-155. R. L. Fleischer and A. Mogro-Campero, Association of subsurface radon changes in Alaska and the northeastern United States with earthquakes, Geochim. Cosmochim. Ac., 1985, 49, 1061–71. Z. Roumelioti, C. Benetatos and A. Kiratzi, The 14 February 2008 earthquake (M6.7) sequence offshore south Peloponnese (Greece): Source models of the three strongest events, Tectonophysics, 2009, 471 (3-4), 272-84. International Scientific Conference eRA-7
  14. 14. http://env-hum-comp-res.teipir.gr/

×