Seismic Studies

1. CHARACTERISTICS OF RESERVOIR INDUCED SEISMICITY
AT TARBELA AND MANGLA DAMS1
Syed Kazim Mahdi
Deputy Director Seismology, Seismic Studies Program, Mangla, Pakistan
sspkazim@hotmail.com
Muhammad Mushtaq Chaudhry
Member Water, WAPDA, WAPDA House, Lahore, Pakistan
memwater@wapda.gov.pk
Muhammad Siddique
General Manager (P&D), Water, WAPDA House, Lahore, Pakistan
gmpdw@wapda.gov.pk
ABSTRACT
The role of water retaining reservoirs in generation and reorganization of the local Seismicity
especially within 20 km. crustal depth and 50 km. radius from the dam sites has always remained
a question to be debated upon since the advent of the twentieth century. Until the early sixties the
changes in local seismicity or Reservoir Induced Seismicity (RIS) were explained due to the
sagging of the reservoir basement caused by the weight of the water and consequent crustal
adjustments. However after the 1960’s some damaging earthquakes (magnitude > 5.0) near
reservoirs in Kriba, Kremasta, (Greece), Koyna (India), Aswan (Egypt), Mangla, and Tarbela
(Pakistan) were related to the development of reservoirs, their filling and drawdown.
In Pakistan two large Dams Tarbela (143 meters) and Mangla (138 meters), have been
constructed in the zone of significant seismic danger (M = 6.0 to 7.0, I = VIII to IX, and a = 0.2
to 0.5 g). Collection of seismic data by the local microseismic networks operating at these Dams
sites has shown that both lie in the middle of active Seismotectonic zones. Active faults are
present at the sites, which are capable of generating large earthquakes (M = 7.5 maximum and a =
0.65 g maximum). Felt earthquakes with shallow focal depth generating magnitudes 4.0 to 5.2 at
the sites are studied. Analysis of RIS characteristics for mainshock – aftershock ratio, regional
“b” values – aftershock ‘b’ values ratio, and aftershock decay rate was carried out, and it was
found that Tarbela and Mangla reservoir displayed similar RIS characteristics as reported for
other reservoirs in the world.
Statistical analysis of the seismic data at both the Dam sites indicates that there is mostly an
inverse correlation between the number of seismic events and reservoir level. At both the
reservoirs the seismicity increases after the drawdown of reservoir.
Key words: RIS, mainshock to aftershock ratio, aftershock decay rate, b-value, shallow depth.
1
73 rd
Meeting, International Committee On Large Dams (ICOLD)
Symposium and Workshop, May 1 – 6, 2005, Tehran, IRAN.

2. 2
INTRODUCTION
The role of water retaining reservoirs in the generation and reorganization of the local seismicity
especially at shallow depth and within 50 km. from the Dam sites has always remained a question
to be debated upon since the advent of twentieth century. Reservoir Induced Seismicity (RIS)
represents the level of ground motion capable of being triggered by the filling, drawdown or mere
presence of a reservoir.
In this paper some RIS characteristics has been analyzed/developed for Tarbela and Mangla
Dams of northern Pakistan, considered among the largest holding reservoirs of the world. The
dams have been constructed in the zone of significant seismic danger where Mag. = 6.0 to 7.0,
Intensity = VIII – IX and acceleration = 0.2 to 0.5 ‘g’ has been observed (Mahdi 2003 & 2004).
Tarbela Dam is a multipurpose Project located on the Indus River about 70 km. NW off
Islamabad (Figure-1). It consists of a Main Embankment Dam (MED), two Auxiliary Dams, two
Spillways, two Irrigation Tunnels and a Power Station. Its MED has a crest length of 2.75 km and
maximum height of 143 meters. Reservoir has an area of about 100 sq. km., with a maximum
depth of 130 meters and gross capacity of 13.7 km3
. The reservoir of Tarbela Dam was first filled
up to a height of 110 meters in August 1974 and then rapidly depleted due to certain technical
reasons. First full impounding of the reservoir was carried out during the 1975 summer and since
then it has completed thirty filling-release cycles.
Mangla Dam is another multipurpose Project located on the Jhelum River about 40 SE off
Islamabad (Figure-1). Its main Structures are, one MED, one Auxiliary Dam, one Dyke, two
Spillways and a Power Station. The MED is 2.10 km. in length and 130 km. in height. Its
reservoir has an area of about 100 sq. km. with a maximum depth of 120 meters and gross
capacity of 12.0 km3
. The reservoir of Mangla Dam was first filled in July 1967 and since then it
has undergone thirty-eight filling-release cycles. Maximum height to which its reservoir can be
filled is presently 115 meters. Government of Pakistan has initiated the “Mangla Dam Raising
Project” which will increase its retaining height by 10 meters and area of reservoir to 120 sq. km.
1. RESERVOIR INDUCED SEISMICITY (RIS)
An earthquake is a failure in the crust caused by an increase in stress and/or decrease in strength
beyond critical limits. Generally, a reservoir will cause a change in both stress and strength in its
vicinity. Stress is affected by reservoir load and strength by changes in pore pressure. A rise in
pore pressure causes a decrease in strength.
The Reservoir Induced Seismicity (RIS) has been well documented at several Dams sites around
the world. In some of the cases the reservoir impounding caused a large and rapid increase in the
frequency of micro-earthquakes, as for example in Kremasta, Greece (Gupta 1986). The earth’s
response to a particular reservoir depends upon regional tectonic stresses, on the porosities and
permeabilities of geological formations underlying the reservoir, on the presence of faults in the
vicinity and on the depth/volume of water in the reservoir. In active seismic environments a
seismic network may be established five years prior to the first impoundment.

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According to Mahdi (1988, 2004), Ali (1989), Simpson (1988) and Gupta (1986), some common
characteristics of RIS are:
1. Reorganization in seismicity is generally confined up to shallow depths i.e. 20 km.
and limited to a radial distance of about 50 km.
2. Increased seismic activity associated with rapid filling/depleting is a direct effect of
loading/unloading through either shear stress or increased pore pressure. These
induced events are mostly of low magnitude. However, after quiescence in
seismicity, felt events may occur with magnitudes up to 5.5.
3. A delayed RIS can occur due to the result increased pore pressure through diffusion
of water pressures into hypocentral regions. The delayed earthquakes are of high
magnitudes and may sometimes have epicenters that are tens of km. away from the
reservoir.
4. The aftershock ‘b’ values are higher than ‘b’ values for normal seismic events
sequences of the region concerned. These aftershocks have a comparatively slow
rate of decay.
5. The magnitude ratio of the largest aftershock to the mainshock is higher and is
order of 0.9.
6. In some cases the seismic activity starts soon after the beginning of the impounding
and grows with the reservoir levels. However, this could be the result of operation
of a seismographic network, which generally coincides with the commencement of
reservoir impounding and gives a more detailed record of seismic events.
7. The observed Intensities are sharply decreasing with the distances from the
epicenters, which usually cluster around the reservoir. This aspect along with
acoustic phenomena associated with triggered seismicity indicates a shallow
activity.
8. It has been shown that instantaneously triggered response is due to added weight
influence, while the delayed triggering is linked with slower pore pressure
propagations. In some cases, large magnitudes at greater depths are also triggered
in this way.
9. There is a trend indicating that greater time differences between the start of
impounding and the maximum-triggered shock entail larger maximum shock.
10. It is noticed that more triggered events are usually linked to normal and strike-slip
faults than to thrust faults.
The RIS has been observed in at least sixty confirmed episodes around the world and as well as
twenty questionable cases (Mahdi 1988 & 2004 and Simpson 1988). Associated seismic activity
is particularly clear when the water in the reservoir is deeper than 80 meters. The height of water
and thus the local level of stresses are more important than the total volume of reservoirs in some
cases. The rate of increase of water level and the durations for which the high levels are retained
also seems to affect RIS. Moderately seismic areas are thought to be at greater risk than very
active or comparatively aseismic areas.

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Figure 1. Geodynamic and Geological Setting of Tarbela & Mangla Dams.
2. GEODYNAMIC AND GEOLOGIC SETTING
The geodynamics of Pakistan is characterized by the collision/coalescence of Eurasian and Indian
Continental Plates (Figure-2), which were once separated by oceanic domains. This process
started during the late Eocene to early Oligocene with formation of the Himalayan ranges. It is
however, also understood that the recent Indo-Pakistan sub continent collision was preceded by a
similar collision immediately north of Pakistan or throughout southern Asia that took place in
Paleozoic era. The Himalayan are believed to form a sharp frontal thrust belt as the southern edge
of a wide collision zone extending north to include Hindukush, Pamir, and other collisional
features of Central Asia.
Relative to Eurasia the Indian Plate is still moving northwards at a rate of 3.7 cm/yr near 730
longitudes east. Indus suture line that coincides with the upper Tsengpo River valley represents
the original line of the continental collision along which linear and well-developed ophiolite
suites are found. These ophiolites are interpreted as the remnants of the oceanic crust of the
Tethys Ocean trapped during the collision between the Indian and Eurasian continental blocks.
Major portion of this convergence was taken up by deformation along northern collision
boundary involving folding and thrusting of the upper crustal layers in shape of Main Karakoram
Thrust (MKT), Main Mantle Thrust (MMT), Indus Darband Fault (IDF), Main Boundary Thrust
(MBT) and Salt Range Thrust (SRT), (Figure-1). Important fault systems of Tarbela and Mangla
dams are discussed further.

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FIGURE-2. Plate tectonic setup of Tarbela and Mangla Dams
2.1 Indus Darband Fault
The Indus Darband Fault (IDF) is a major tectonic shear of Tarbela Dam which traverses the river
channel under the Dam near the right bank of Indus. It displays strike slip signatures in the
sections located upstream of Tarbela Dam. Frictions shear heating along the footwall of the fault
further confirms its lateral movement. North of the Dam, IDF extends along the Indus and larger
part of it passes through the Indus valley. Two north-dipping thrusts splay off from the master
fault towards the left bank of the Indus at Kharkot and Dangror. Further north, upstream of
Darband in the Black Mountain area, IDF splits into several north south striking isolated shears,
some of them running parallel to each other (Tahirkheli 1998). Two major strike slip faults
namely Puran and Chakesar, striking north and south, appear to be the continuation of IDF, each
having more than 15 km. surficial length are located on the western bank of the river. These faults
extend northward towards the Main Mantle Thrust (MMT), the southern suture.
2.2 Tarnawi Punjal Fault (TPF)
Tarnawi Punjal Fault (TPF) emanates from the apex of Hazara Kashmir syntaxes and extends
westwards through Galiat Hills. Its topographic expression remains intact in the west through
Sherwan Hills till it enters the Haripur Plains, where it is concealed underneath the alluvium. At
the northern edge of Baso Mera the TPF appears to bifurcate into two faults, one after emerging
from the alluvial ascend through the northern edge of Gandgher Range east of Sarikot and
traverse the range with north-south strike.

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2.3 Hazara Thrust System (HTS)
The Hazara Thrust System (HTS) of faults connects the Himalayan Thrust near its north west end
in Kashmir (740
East & 340
North), with the Baluchistan strike slip fault system at its north
eastern end (700
East & 730
North). The HTS separates the Tertiary Formation and Mesozoic in
the southeast and Paleozoic in the northwest. Seismic network data indicates that the shallow
portion of HTS is active, but presently it is in a period of seismically stress accumulation (Mahdi
2003).
2.4 Main Boundary Thrust (MBT) Fault
One of the most important seismotectonic features concerning the Mangla Dam Project is the
Main Boundary Thrust (MBT) fault, which partially detaches the old Himalayan rocks from the
more recent ones. It makes the contact zone between the Eurasian and Indian Plates. It starts from
about Latitude 290
north and Longitude 950
east off India and extends up to the Indus River at
Latitude 340
north and Longitude 730
east. An offshoot of MBT near Mangla is the Riasi Thrust
Fault (RIF).
3. SEISMIC NETWORKS AND DATA
Independent networks of high/low gain VHF telemetry seismic stations are recording tectonic
activities around the Tarbela and Mangla Dams. At Tarbela the network with thirteen stations
was established about ten months (August 1973) before the first impounding. While at Mangla
only three stations remained working for six months before the first impoundment (June 1967)
through December 1994, when the number of stations was increased to eleven. Two more seismic
networks are operative around Islamabad, which is near to the Dam sites.
The data used in this study consist of seismological parameters of earthquakes (such as
magnitude, epicenter location and depth) which are determined using HYPO71/HYPOFAST
from P & S waves arrival times recorded at the stations of all the four networks working in the
area. Local velocity structures and Magnitude scales have been developed for the networks. Only
those events with magnitudes > 0.0 are used in order to ensure accuracy. Almost all the seismic
events of coda length 10 sec are located. The average root mean square (RMS) of travel time
residuals is 0.1 sec. The average horizontal error (ERZ) and vertical error in depth (ERZ) are < 2
km. and 5 km. for an area > 50 km. For an area of more than 50 km. radial distance the ERZ and
ERZ are < 0.25 km. and 0.5 km. respectively. Computer programs developed by Mahdi &
Nadeem (2003) are used to separate and process the data for studies. These Programs divide the
area around the two dams into different seismic zones and then computes the seismicity
pertaining to each zone.
In order to examine the Induced Seismicity with the Reservoir Elevations and calculate the delay
time for both the Dams, zones of 20 km. depth within 50 km. radius were used. Aftershocks
followed by main events were excluded from the data catalogue. The zones were named as
Tarbela Seismic Zone (TSN) and Mangla Seismic Zone (MSN) respectively. The zones were
chosen because:

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a. Within an area of 50 km. radius the Tarbela network has located about 15000 seismic
events (from August 1973 through September 2004) and 80 % are confined to depths
of 20 km. In the same radial distance the Mangla network located 10500 seismic
events (from January 1967 to September 2004) with about 75 % coming from 20 km.
depth.
b. The seismic events have been accurately located in these zones and the Fault Plane
Solutions (FPS) when required is easily computed/available.
c. Previous studies have also shown RIS effects in these areas.
4. PRE AND POST IMPOUNDING SEISMICITY
Comparison between pre impounding and post impounding seismic activity is necessary in order
to resolve the RIS from the natural tectonics of the area. For these purpose seismic events located
within zones of 0-100 km., 0-50 km. and 0-50 km with 20 km. depth were analyzed.
In the Tarbela region the pre impounding seismicity recorded was collected over a period of ten
months (August 1973 to May 1974) and therefore it is only an approximation of the background
seismicity. From the area 0-100 km. off Tarbela about 379 or 37.9 per month (p/m) seismic
events were recorded. Within the radial distance of 50 km. the seismic events were 312 or 31.2
p/m and for the TSZ (50 km. radius & 20 km. depth) the seismic events were 285 or 28.5 p/m. In
the first post-impounding period (June 1974 to May 1975) the seismic events were 397 or 33.1
p/m, 327 or 27.5 p/m and 210 or 17.5 p/m, for the areas of radial distances 0-100 km., 0-50 km.
and TSZ respectively. During the second post filling time the seismic events were 413 or 34.4
p/m, 323 or 26.9 p/m and 205 or 17.1 p/m. A comparison of pre and post impounding seismicity
reveals that a large decrease in seismicity occurred in the post impounding periods. That decrease
was also reflected in the distribution and number of seismic events. It was more pronounced in
the downstream of the reservoir.
At Mangla Dam only five months pre impounding seismic data (January-May 1967) is available.
In the radius of 0-100 km., 0-50 km. and MSZ (50 km radius & 20 km. depth) the five months
data were 66, 42 and 31 respectively (13.2 p/m, 8.4 p/m and 6.2 p/m). During the first post-
impounding period and for the same radial distances the number of seismic events was found to
be 69, 38 and 22 respectively (5.7 p/m, 3.1p/m and 1.9 p/m).
In the second post impounding cycle the number of located seismic events were 73, 35 and 20
respectively (6.1 p/m, 2.9 p/m and 1.9 p/m) for the three zones.
A close examination of Figure-3 (where yearly seismicity of Tarbela and Mangla Dams are
plotted), demonstrates that the effect of reservoir is clearly evident at the TSZ and MSZ
respectively. Both the reservoirs have certainly been affecting the seismicity in their respective
vicinity and probably been doing so by more than one mechanism. After a large drop in
seismicity upon the first impoundment, the seismicity continued to be modulated by the reservoir
fluctuations. The phenomena can be explained in terms of changes in stress induced by the
reservoir load and can be interpreted in terms of a constant strain rate or as the effect of increased
pore fluid pressure reaching seismogenic depths.

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Figure-3 SEISMICITY LEVELS AT TARBELA & MANGLA DAM PROJECTS DURING 1975 THROUGH 2004

9. 9
A long-term effect is super imposed on the yearly cycles of reservoirs levels and seismicity.
During the first complete filling cycle the seismicity near Tarbela and Mangla Dams dropped
drastically. Since then the yearly number of seismic events rose and dropped steadily. In both the
cases the seismicity has increased and decreased over periods of 8 to10 years.
A long-term rise in seismicity would be expected, for tectonic strain will continue whether the
reservoirs are there or not. The reservoirs increase the vertical component of stresses, which
reduces differential stress and strain rates. The reduction in differential stress is for some period
and temporary. In order to regain the strain rate demanded by the natural tectonics or the motion
of Indian Plate towards the Eurasian Plate, the horizontal stress has risen for the last eight to ten
years (Figure-3).
5. SEISMICITY AND RESERVOIR LEVEL
One way to categorize the Reservoir Induced Seismicity (RIS) is to compare the monthly average
rate of occurrence of seismic events within the study area with the reservoir water elevations and
average rate of change in water elevations. To identify that effect Figure-4 is prepared by
considering the seismic events located in the area of study at both the sites from the year 1967
through 2004. The data has been divided into periods of 1967 to 1974, 1975 – 1984, 1985 – 1994
& 1995 – 2004 and plotted against the average trends of reservoir elevations (from 1967 to 1974
data available for only Mangla).
A close examination of Figure-4 reveals that average number of seismic events decreased during
the period 1985 – 1994 and increased during 1995 – 2004. At both the Dams that increase was
even more than the level of 1975 – 1984. It may be attributed as the delayed effect of both
reservoirs to the natural Seismicity of the area. Such character may be interesting for study in the
next ten years period.
Another similar relationship at both the Dam sites suggests that the response of reservoir on local
Seismicity is reciprocal i.e. the seismicity mostly decreases with the increase in the elevation of
reservoir. This effect can be postulated as the negative effect of reservoir load on differential
stress in a tectonic regime where the minimum compressive stress is sub-vertical or a regime of
thrusting. Such a regime has been observed and is expected along the Himalayan mountain front.
During the last decade the negative effect is much more pronounced at Mangla Dam than Tarbela
Dam.
By correlation of the trend lines with the reservoir levels it is observed that at both the Dams the
delay time after the drawdown of reservoirs and number of seismic events has decreased from 90
to 60 days at Tarbela and 75 to 30 days at Mangla. This may lead to the conclusion that severe
reservoir effect in the shape of increased pore pressures and in terms of increased seismicity are
expected in the areas mostly in the months of November through January. This rise in pre fluid
pressure is expected to be gradual because water behaves as a compressible fluid at seismogenic
depths and because permeability at these depths is generally low.

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Fig.-4 Monthly Average Seismicity Vs Average Reservoir Level at Tarbela & Mangla during 30 Yrs Periods
RESERVOIR ELEVATION 1995 TO 2004
1975 TO 1984 1985 TO 1994

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6. ANALYSIS OF MACRO AND FELT SEISMIC EVENTS
Study of macro and felt seismic events in the vicinity of the reservoirs has suggested some
consistency in the focal depth, ratio of mainshock (MS) with maximum aftershock (AS),
aftershock decay rate and the ratio of regional ‘b’ values with the aftershock ‘b’ values. Such
relationships for Tarbela and Mangla Dam Projects were calculated and presented in Table-1
below.
Table-1: Relationship in the Reservoir induced Properties at Tarbela and Mangla Dams.
TARBELA DAM PROJECT MANGLA DAM PROJECT
DATE MAG. DEP.
km
AS:MS AS
DECAY
RATE
AS
b
VALUE
DDATE MAG. DEP.
Km.
AS:MS AS
DECAY
RATE
AS
b
VALUE
26.03.1974 4.8 15.0 0.88 Slow 0.82 12.04.1974 4.4 20.0 0.80 Slow 0.75
18.07.1974 4.5 12.5 0.93 - 0.80 10.11.1975 4.5 20.0 1.00 - 0.75
07.08.1974 4.2 15.0 0.90 - - 09.04.1977 5.0 05.0 0.92 Slow -
15.11.1974 4.4 10.0 0.93 - - 07.05.1978 5.0 12.5 1.00 - 0.85
25.11.1974 4.6 15.0 0.82 Slow 0.78 03.04.1982 4.5 10.0 0.85 Slow 0.72
12.01.1976 4.4 15.0 0.75 - - 25.03.1996 4.4 12.5 0.91 Slow 0.85
21.08.1976 4.2 15.0 0.90 Slow 0.83 29.07.1997 4.4 12.5 0.89 Slow 0.80
03.03.1977 4.5 05.0 0.86 Slow 0.85 17.02.1999 4.5 12.5 0.96 - -
05.10.1977 4.5 12.5 0.88 - 0.85 04.02.2001 4.2 13.7 0.91 Slow 0.83
05.01.1978 4.6 17.5 0.75 Slow 0.82 27.01.2002 4.4 15.6 0.90 Slow 0.88
04.01.1979 4.5 15.0 0.91 Slow 0.86 18.04.2002 4.4 14.6 0.93 Slow 0.88
10.03.1979 4.4 15.0 0.93 - 0.85 22.11.2002 4.2 13.8 0.93 Slow 0.88
27.04.1979 4.3 17.5 1.00 Slow 0.82 28.02.2003 4.5 17.8 1.00 Slow 0.80
18.08.1979 4.4 12.5 0.92 - - 04.05.2003 4.5 14.5 0.93 Slow 0.85
14.04.1982 4.5 15.0 0.93 Slow 0.84 11.05.2003 5.0 12.6 0.92 - 0.90
10.07.1986 4.5 02.0 0.88 Slow 0.80 22.05.2003 4.7 12.4 0.89 Slow 0.85
25.03.1992 4.9 13.3 0.92 Slow 0.85 29.08.2003 4.4 12.5 0.90 Slow 0.88
20.02.1996 5.2 05.0 0.94 Slow 0.85 16.10.2003 4.7 08.3 0.89 Slow 0.90
10.04.1997 4.2 13.7 0.88 - 0.80 30.11.2003 4.2 12.8 0.90 Slow 0.90
05.09.1997 4.4 04.5 0.91 Slow 0.82 10.09.2004 4.4 13.5 0.84 Slow -
Slow rate of decay in the pattern of aftershock compared to normal sequences is an important
characteristic of RIS. The time distribution of aftershocks is given by the inverse power law, i.e
n(t) = Ct –h
where n(t) is the frequency of aftershocks per unit time, C and h are constants and t is
the time elapsed after the main event. At Tarbela and Mangla Dams when the decay rate is
studied for a period of 50 to 75 days after a big event it gives a slow decay rate pattern, refer
Figures 5 & 6 as examples.

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Another feature that is common to most known cases of RIS is the shallow focal depth, i.e. the
seismic events occur within a focal depth of 20 km. All the seismic events analyzed in Table-1
have the focal depth of 20 km or less and are thus comparable to the shallow focal depths
reported for induced seismicity from other sites. It is to be noted that the focal depths for normal
seismicity at TSZ and MSZ is 30 km. (Mahdi 2003).
In the Table-1 the ratio between mainshock and maximum aftershock is > 0.90 in most cases,
which is another characteristic/indication of RIS.
7. CONCLUSIONS AND RECOMMENDATIONS
Tarbela and Mangla Dams are located in a highly active seismotectonic regime where the crustal
blocks are in motion. The presence of reservoirs has modulated the seismicity of Tarbela and
Mangla Seismic Zones (50 km. radius & 20 km. depth). The response of reservoir filling is
negative/reciprocal i.e. the seismicity mostly decreases with the increase in the elevation of
reservoir. Long and short-term effects are clearly evident in the yearly cycles of reservoir filling
and drawdown. The phenomena is attributed to the changes in stresses induced by the load of
reservoirs and can be interpreted in terms of a constant strain or as the effect of increased pore
fluid pressure reaching seismogenic depths. The time lapse between the drawdown and high
frequency of seismic events has shortened and now it is 60 and 30 days at Tarbela and Mangla
Dams respectively. At both the sites many macro seismic and felt events have indicated RIS
characteristics. It is recommended that while making planning the construction of Dams having
height 100 meters or more, Seismograph and Strong Motion Accelerographs (SMA) networks be
commissioned at least five years before the construction is started.

13. 13
REFERENCES CITED
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Mexico State University, La Cruces, NM 88003. USA.
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Oroville California RIS”; Physics of Earth & Planetary Interiors, Vol. 44 No. 2.
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Andhra Pradesh India, Physics Of Earth & Planetary Interiors, Vol. 44 No. 2.
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Seismic Parameters for large Dams”, Paris,
6. International Commission on Large Dams (ICOLD), (1996), ”Guidelines for Selecting
Seismic Parameters for large Dams”, Paris,
7. Jacob. K. H., Seeber, L. et al.: (1979), “Tarbela Reservoir Pakistan a region of
Compressional Tectonics with Reduced Seismicity upon initial Reservoir filling”, Bluttin of
Seismological Society of America, Vol. 69,.
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Second International Conference on Case Histories in Earthquake Engineering, Missouri
Rolla, USA.
9. Mahdi, S. K., et. Al.; (1999 through 2004), “Annual Seismicity Reports for Tarbela &
Mangla Dams Pakistan, (unpublished office files).
10. Mahdi, S. K., et Al: (2003); FORTRAN Language Computer Program For The
Seismotectonic Studies Of Tarbela & Mangla Dams; (Office Files).
11. Seeber, L., et. Al.; (1980), “Seismic Activity At The Tarbela Dam Site & Surroundings”;
Proceedings of the International Committee on Geodynamics, 23-29 Nov. 1979, Peshawar,
Pakistan.
12. Seeber, L. & Armbruster, J., (1983), “Continental Subduction along the NW & Central
Portions of the Himalayas Arc”, Bolietting Geofisica Teorica, Vo. XXV.
13. Simpson, D. W, (1976), “Seismicity Changes Associated With Reservoir Loading”,
Engineering Geology.
14. Tahirkheli, R. A. K., (1988); “Seismicity in the vicinity of Tarbela Dam Project”. Fourth
Periodic Inspection of Tarbela Dam Project; (Unpublished office files).