OCTOBER 08, 2005 RUPTURE ALONG JHELUM THRUST AND1

POST EARTHQUAKE SCENARIO ALONG JHELUM FAULT

Mahdi, Syed Kazim Director Seismic Studies, WAPDA, Tarbela Dam Project, Pakistan

sspkazim@hotmail.com

ABSTRACT A powerful shallow focus earthquake of Mw 7.7 devastated the Kashmir-Hazara Region (KHR) on October 08, 2005, killing over 0.1 million people and resulting in infrastructures damages whose rehabilitation will cost over five billion dollars. The earthquake ruptured the southwest Jhelum Thrust (JT) (also known as the Tanda-Muzaffarabad fault), which was inferred to be as active, in a region where the river incises directly into the Murree sandstones on the west side of the valley (footwall of JT), while it has abandoned large inset terraces along the east side (hanging wall of JT). Following the occurrence of this earthquake, a large amount of new geophysical and geological information is now available, providing key new insights into the regional geotectonic framework and origin of the Kashmir-Hazara Syntaxis (KHS). The JT is a recent offshoot of Pir-Panjal Thrust, which jumped southwards by about 20 km, perhaps in the last five million years. The fault plane solution implies predominant thrusting towards the southwest with a slight component of right-lateral slip. The surface rupture of the Kashmir-Hazara earthquake probably ranks as the most spectacular rupture documented to date along the entire Himalayan range The occurrence of Kashmir-Hazara earthquake confirms that the active Jhelum Thrust (JT) and Jhelum Fault (JF), in a region located well north of the Main Himalayan Frontal Thrust, accommodate roughly EW-oriented, present day shortening related to “zipper tectonics” within the part of the KHS. Such EW shortening is a consequence of slip- partitioning at a much greater scale, co-involving the Chaman Fault to the west and Karakorum fault to the northeast. Many of the unexplained aftershocks with different focal mechanisms reflect the shift of stresses towards the other active faults. One such shift is evident along the Jhelum Fault which extends southwards from Muzaffarabad in a north-south direction, before veering west towards Islamabad, going further down to Mangla and ending into the Salt Range. The stresses indicate that another big earthquake might occur with a location propagating southwards on the Jhelum Fault. Detailed seismic studies of the areas covering the Jhelum Fault where big Structures have been planned for the near future and installation of seismic instruments are highly recommended. Key Words: Jhelum Thrust Kashmir-Hazara Earthquake, Kashmir Hazara Syntaxis, and Jhelum Fault. 1 International Seminar on Post Muzaffarabad Earthquake Scenario August 22 & 23, 2008, Baragali, PAKISTAN. Organized by QAU, NCEG NCP & HEC.

Figure 1. Tectonic setting of the October 8, 2005, Kashmir earthquake. Rupture areas

of major Himalayan earthquakes documented from historical studies [1] and paleoseismic investigations [4]. Shaded ellipses show estimated locations of ruptures in 1413, 1555 and 1905. Major active faults, modified from [5] and [4], are shown in red. Dashed lines indicate approximate location of blind thrust faults. Velocity of peninsular India relative to stable Eurasia computed from the Euler pole of the Indian plate determined by Bettinelli et al. [6]. MFT: main frontal thrust fault. MBT: main boundary thrust fault. IKSZ: Indus-Kohistan Seismic Zone [7].

INTRODUCTION The Mw 7.7 (shallow depth 16.62 km) mega earthquake, which struck Kashmir & Hazara regions of Pakistan on October 08, 2005, claimed over 0.1 million lives and destroyed infrastructures whose rehabilitation will cost more than five billion dollars. This is up till now the most destructive earthquake to have occurred along the Himalayan arc. Several earthquakes during the 20th century have almost certainly approached or exceeded Mw 8.0, in particular the 1905 Kangra and the 1934 Bihar-Nepal earthquakes [1], but those did not cause as many victims as the 2005 episode (Figure-1). This is a sad reminder that seismic

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weakness has risen critically over the last few decades due to the increase of population in the region and probably inadequate awareness of seismic hazard [2, 3]. The region was thus mostly not ready for the occurrence of such a large shallow earthquake and, given the concentration of population in Muzaffarabad, Balakot, and in scores of other mountain villages, the earthquake produced untold death toll and damages. Epicenter of the Kashmir-Hazara earthquake is located at the western periphery of the Himalaya, where the arc meets the Karakorum, Pamir, and Hindukush ranges. The physiography of the range, as well as tectonic structure defines a syntaxis, called the Kashmir Hazara Syntaxis (KHS), outlined by the hairpin rotation of the Main Boundary Thrust (MBT). The MBT is a most important fault bounding the Himalayan range that has thrust metasediments of the Lesser Himalaya over the Tertiary molasses of the Himalayan foreland [4]. Active deformation in the area results from the 3 cm/yr northward notch of the northwestern Indian Peninsula into Eurasia (Figure-1). Along the northwestern Himalaya, a fraction of that junction, estimated to about 1.4 cm/yr [5], is absorbed by thrusting perpendicular to the range.

REGIONAL GEOLOGY In Kashmir-Hazara region of Northern Pakistan the orogen is composed of three main tectonostratigraphic terrains (Figure-2), the Asian plate to the north, the Indo-Pakistan plate to the south, and the Kohistan island arc sandwiched between. The Kohistan arc can be divided from the Asian plate by the Northern

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or Shyok Suture and from the Indian plate by the Main Mantle Thrust (MMT). The Asian plate Karakorum is divided into the Northern Sedimentary terrain of Paleozoic and Mesozoic Formations, the Karakorum Batholiths of Cretaceous to Miocene age, and the Kohistan arc, consists of Late Cretaceous and Eocene plutonic belts, and pyroxene granulites, calc-alkaline volcanic, amphibolites, and minor metasediments. The Indian plate can be sub-divided into three tectonic unit’s viz. (from north to south these are) (1) an internal metamorphosed unit, (2) an external un-metamorphosed or low grades metamorphosed unit, and (3) the foreland basin sediments. The internal unit consists of cover and basement rocks. The basement rocks are predominantly high-grade gneisses; the cover rocks are predominantly greenschist to amphibolites grade metapelites and metapsammites metamorphosed during the Himalayan orogeny. The internal zone is separated from the external zone un-metamorphosed to low-grade metamorphic Precambrian sediments and dominantly Mesozoic to Eocene Tethyan shelf sediments by the Panjal Thrust (PT). Farther to the south, the MBT separates these rocks from the Tertiary foreland basin deposits. The Main Frontal Thrust (MFT) delineates the southernmost extent of the foreland basin fold and thrust belt. The more than 8 km thick red bed Balakot Formation in the KHS as a steeply north dipping, normal homoclinal stratigraphic succession, conformably overlying the Paleocene-aged shallow marine Patala Formation and Lockhart Limestone. The Balakot Formation is truly variably deformed and folded by a series of tight folds (wavelengths and amplitudes of I km). The Patala and Lockhart Formations unconformably overlie the Late Precambrian to Cambrian Abbottabad Formation, which forms the core of the Muzaffarabad anticline. The lower part of the Balakot Formation is structurally imbricated and isoclinally folded with the Patala Formation, which in turn is in thrust contact with the overlying Abbottabad limestones. The entire package is complexly faulted, with systematic top to the southwest thrust shear sense. Therefore, in summary, the Balakot Formation red beds lie in thrust contact with the Paleocene aged shallow marine Patala Formation and Lockhart Limestone below, and are tectonically intercalated with an underlying dark gray marl formation. Jhelum Fault is a NE dipping strike-slip fault following the western margin of HKS bend. Rocks belonging to Miocene, Cambrian and Pre-Cambrian periods exposed along its trace are highly deformed due to recurring shear zones. Individual blocks of Panjal Volcanic and Triassic limestones have been found dragged for several kilometers southward. An accumulative left-lateral offset of about 31 km is indicated on the western limb of the Syntaxis. It apparently dislocates from the Main Boundary Thrust and terminates at the eastward continuation of some of the geological structures of North West Himalayan Fold and Thrust Belts. These tectonic relationships indicate Jhelum fault as the youngest major tectonic feature in the syntaxial zone.

TECTONOCS OF KASHMIR HAZARA EARTHQUAKE Monitoring by the local Tarbela seismic network around the KHS has revealed an alignment of seismicity, called the Indus Kohistan Seismic Zone (IKSZ) [10]. The IKSZ strikes parallel to the north-western Himalaya, but extends beyond the HKS. This seismicity extends northwestwards the belt of seismic activity that follows the front of the entire Himalaya. This is an indication that northwest-trending Himalayan basement structures extend beyond the syntaxis and that the change in the strike of the MBT is a rather superficial feature, probably related to the infracambrian salt [10].

Figure 3. Geology and Seismotectonic of Kashmir Hazara Region.

The fault that ruptured during the October 08, 2005 Mw 7.7 earthquake is a thrust that has been identified characteristically along the Jhelum valley from Muzaffarabad to Garhi and farther south. Before the earthquake this south-west

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thrust was not accurately mapped on the 1/50,000 scale geological maps (trace mostly along the Jhelum, with a dip towards west!), except in the instant vicinity of Muzaffarabad where it evidently emplaces Precambrian (mostly white-grey dolomites) capped by early Eocene nummulitic limestone on top of the schistosed Murrees (Figures 3 & 4). When visited in the field the JT stands out undoubtedly in the geomorphic landscape of the middle-Jhelum valley. Thus it is more justified to be called as Jhelum Thrust (JT). Previously it has been mapped and identified as Tanda-Muzaffarabad fault [11]. However, at that time just the northern stretch of the fault was assumed to be active. It is certainly the west-directed thrusting on the JT that has made the Jhelum valley strongly asymmetric: the river incises in a straight line into the Murree sandstones on the west side of the valley (footwall of JT), while it has abandoned large inset terraces along the east side (hanging wall of JT) because it keeps being enforced southwestwards by the rise of hanging wall. Near Thotha, such fluvial terraces, which include far-traveled boulders, stand more than 200 meters over the riverbed. Tributary catchments east of the river, where mountain heights reach 3200 meters, are well developed, while they are nearly insignificant along the west bank, where there is a less relief (≤ 1400 meters). This is because deep incision is promoted by the rise of the JT’s hanging wall. Just north of Muzaffarabad, the thrust steps leftwards across the Neelum, continuing into the Kunar valley alongside high faceted spurs to no less than Balakot. It might extend farther than west, north of Manshera. As discussed afterward, the steps at the Jhelum crossing is one place where some of the most remarkable cumulative seismic displacements (uplifted terraces) on the JT are observed. These steps (Figure-2) are interpreted to reflect offset of the JT by the Jhelum Fault (JF), which is a confirmed active fault [12]. The JT is less well-known geological than geomorphic feature, because it cuts mostly across rocks of similar age. This may explain, in part, why it had not been clearly documented and mapped up till now. In cross section, it dips eastwards below a large hanging wall anticlinorium of schistosed Murree red-beds, whose escalation it has orchestrated. Only in the vicinity and than scarcely, dose this anticlinorium’s core exhumes the Precambrian substratum of the red beds, near Muzaffarabad. This indicates that the JT is very youthful feature (possibly only a few million years old). Undoubtedly the JT match up neither to the Main Frontal Thrust (MFT), Main Boundary Thrust (MBT), Main Central Thrust (MCT) and nor to other “Dun” thrusts which have been mapped farther West. Somewhat it coincides with a segment of the well known Indus Kohistan Seismic Zone (Figure 5), lateral equivalent of the principal ramp of the Main Himalayan Thrust (MHT) in Nepal. As confirmed by the outstanding evidence of surface rupture, described in the later topics, it is now definite that at the discussed location (unlike in Nepal), the JT reaches the surface instead of remaining blind. The idea that thrusts like JT should be blind everywhere, is so deep-seated in most minds, that till date no

surface rupture had yet been realistically mapped, and most landscape disturbances had been interpreted to reflect slope instability and mass-wasting.

Figure 4. SAR-Radar Image of Kashmir Hazara Region. SOURCE & KINEMATICS OF KASHMIR HAZARA EARTHQUAKE The Kashmir-Hazara earthquake originated at 0850 Hrs (PST) or 0350 Hrs (UTC) on October 08, 2005. Within an uncertainty of ± 1 km., the epicenter of the earthquake computed by Seismic Studies Program (SSP), WAPDA Mangla Dam Project (MDP), is at Lat. 34.540 North and Lon. 73.590 East, which places it near the surface trace of the Pir-Panjal thrust north of Neelum River. The focal depth is 16.2 Km. and on Figures 3, 4 & 5, it lies exactly on the JT-IKSZ blind fault, below the Pir-Panjal trace of the MBT, consistent with the epicenter location. The Kashmir Hazara Earthquake (KHE) of October 08, 2005, is thus clearly an event that activated only the JT, somewhat upwards and southwards of its inferred intersection with the Pir-Panjal MBT (Figures 3 & 4). This may be taken as credible idea that the later is now inactive, having been superseded by the JT.

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Figure-5 Orientation of Jhelum Thrust & Jhelum Fault. Moment of the earthquake was projected to range between 2 and 3 x 1027 dyne.cm that match to a moment magnitude of Mw on the order of 7.7. The rupture time was computed as ≈ 30 sec. Seismic Studies Program (SSP) WAPDA, Mangla and several other groups (Figure 6) came up with fairly well constrained Fault Plane Solution [12]. The best fit for the attitude of the nodal plane coinciding with the fault plane yield a rather well constrained azimuth of ≈ 3300, and somewhat less constrained dip of ≈ 35-400 towards the NE. It is in amazing agreement with the JT surface trace mapped in the field. The scrap of fault that slipped during the earthquake may be approximated by an ellipse 50-70 km. long in the NW-SE direction, and 20-30 km. wide in the transverse direction. The length of this pair is in fair conformity, with the length of the fault along which major surface deformation is observed in the field, from Balakot to the mountains south of Hattian (50-60 km., up till 70 km). Fault Plane Solutions computed by various groups indicate thrust faulting with a slight lateral component. In view of the regional tectonics, aftershock activity, fault plane dipping to NE should be the

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causative fault, and the lateral strike-slip component of the faulting implies dextral motion of the fault. The unexplained aftershocks rupture of other faults having different focal mechanisms. Of particular interest the aftershocks that lie in the West of JT and on either side of Jhelum river valley downstream of Muzaffarabad, They lie in the area crossed by the other major active fault of the region, the Jhelum fault, which extends southwards of Muzaffarabad in the NS direction, before veering west towards Murree and Islamabad.

Figure 6. Focal Mechanism of Kashmir Hazara Earthquake Regarding the mechanics and quantity of faulting, the Fault Plane Solution implies predominant thrusting towards the SW with a slight component of right-lateral slip (≤10%). The maximum slip on the fault plane was on the order of 6 meters, with most of it in the top 10 to 5 km of the crust. As presented later, these results are in excellent agreement with those independently obtained from satellite geodesy, particularly Synthetic Aperture Radar Interferometry (InSAR), as well as with surface rupture evidence derived from fieldwork carried out by the author and colleagues.

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In the field it was observed that the earthquake caused considerable uplift, on the order of 1 to 2 meters of ground surface within a ≈ 10 km wide belt following the JT trace from ≈ Lat 34.02 N to 34.60 N. This upward motion is now readily understood to characterize incremental growth of the Neelum anticlinorium, which is indeed most simply interpreted as large ramp anticline, heaved and folded by repetitive seismic slip on the JT, in keeping with geological and geomorphological interpretations. It is such unabated vertical uplift that explains the prominent incision of tributary streams on the NE side of Jhelum River between Garhi and Muzaffarabad. The consistent, rather well constrained kinematic parameters of the earthquake confirm that the JT is a major active fault, possibly the more important of the two regional active faults that meet at Muzaffarabad. Although there is still no direct information on the average slip rate on the thrust, the occurrence of the Kashmir-Hazara earthquake, with many meters of slip, suggest that this slip rate might be significantly high [12]. STRESS CHANGES INDUCED BY KASHMIR-HAZARA EARTHQUAKE The occurrence of Kashmir-Hazara earthquake confirms that the active Jhelum Thrust and Jhelum Fault, in a region located well north of the Main Himalayan Frontal Thrust (which runs along the southern front of the Salt Ranges), accommodate generally EW oriented, present-day shortening related to “zipper tectonics” within the tightest part of the KHS. Such EW shortening is a outcome of slip-partitioning at a much greater scale, co-involving the Chaman Fault to the west and Karakorum fault to the northeast [16]. From the locations of aftershocks it is observed that greater part of the aftershocks of the Kashmir-Hazara earthquake presents increased stresses north of Balakot and south of Hattian. Shinkari seismic station installed by the WAPDA Seismic Observatory during 1973 effectively detected the IKSZ very close to its location during 1973-78. Since the October 08, 2005 earthquake and till date clusters of events are being recorded allover the IKSZ. Such stress increases may have brought the Kotli-Riasi Thrust, to the south, and the Indus Kohistan Seismic Zone ramp north of Balakot nearer to rupture. The effect is seen secondary at Kotli, but quite considerable north of Balakot. Many aftershocks remain unexplained because they fall in lobes of decreased Coulomb stress. In such areas, thrust with mechanisms similar to the Kashmir-Hazara earthquake is now less likely to rupture. These aftershocks thus most likely reflect rupture of other small faults with different focal mechanisms. Of particular interest is the concentration of aftershocks due west of Jhelum Thrust, along and both sides of Jhelum river valley downstream from Muzaffarabad. They lie in the area crossed by other major active fault of the region, the Jhelum Fault (JF), which extends southwestwards from Muzaffarabad in a NS direction, before veering west towards Murree and Islamabad.

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Field observations indicate that the JF, whose geomorphic signature is sharper than that of the JT, marks the base of the steep, ≈ 1-2 km-high range-front that has forced the 1600 southward hairpin turn of Jhelum River just south of Muzaffarabad. Its ≥ 50 km-long trace cuts and offsets left-laterally nine west bank tributaries of the river. Unlike the JT, it dips steeply westwards and is a major geological contact (Murree stretch of MBT), along which the Proterozoic Hazara slates are thrust over the Murree red-beds. Its present-day kinematics (mostly left-lateral slip) makes it different from JT, requiring clockwise rotation (by at least ≈ 600) of the maximum horizontal stress west of Thotha. The Jhelum Fault (JF) is located at a distance of about 50 km East of Islamabad. This fault was reported by original researchers to extend along Jhelum River from north of Muzaffarabad to near Jhelum and further southward to Chaj Doab area. During recent studies it was investigated whether this fault extends southward up to Jhelum or not. Oil and Gas Development Company Ltd. (OGDCL), has mapped a fault parallel to Jhelum River up to Palala Mallah, beyond which it takes a southwest bend and extends parallel to other faults (Dil Jabba, Lehri) of the area as a thrust fault. The unexplained aftershocks of the Kashmir Hazara earthquake are in fact due to the stresses loading the JF. When adapted to the left lateral mechanism of this fault, the calculations indicate that its northernmost, north-south striking segment has indeed being brought considerably closer to the left-lateral strike-slip rupture, with a 15-20 bars increase in such stresses. This may be taken to specify that, in years to come, another ≈ 7.5 earthquake might nucleate near Muzaffarabad, with a dislocation propagating southwards on the JF. SEISMICITY OF JHELUM FAULT Instrumental recording of the earthquakes started during 1904. The number of seismic stations remained small in South Asian region until 1960 when the installation of high quality seismograph under World Wide Standard Seismograph Network (WWSSN) increased the quality of earthquake recording. The Seismic Studies Program (SSP) of WAPDA, Mangla, has prepared a comprehensive catalogue of earthquakes since 1960. It has collected seismic data from the Mangla, Tarbela, USGS and ISC. With the help of catalogue many research studies and project have been done. In one of the studies [14], based on their homogeneous tectonic and seismic characteristics the area around Mangla has been divided into six seismic zones viz. MMT, MBT, Riasi, Hazara, Salt Range and Jhelum Thrust Zone (JTZ). The data for each zone has been complied through FORTRAN IV computer program SEISMOTECTONIC, written by Mahdi et. al. in 2003 [15]. The data indicates a lot of seismic activity along the three seismic zones lying in the NE portion of Mangla. The seismicity along JTZ, before the major earthquake of October 08, 2005, shows a moderate behavior (Table-1).

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ABNORMAL EARTHQUAKS ALONG JFZ For this study and to keep the earthquake locations accurate/homogenous the 10 km area on both sides of Jhelum fault is known as Jhelum Fault Zone (JFZ). By studying the instrumental seismic data (since 1960) along JFZ [12], a quiescence of magnitude greater than 5.0 earthquakes is observed (Table-1). Seismicity is mostly concentrated along the northern and southern portions of JFZ, while its central segment shows significant gap in seismicity. However, during 1999 and 2000, south of Muzaffarabad near tunnel, active mudflows occurred along the JFZ [12]. After the mega Kashmir Hazara earthquake of October 08, 2005 the landslides, mudflows, and uplifted, tilted, and deformed river traces are observed along the JFZ from Balakot to Mangla. The Holocene river gravels are aligned parallel to the brittle shear zone of the fault. The fault shows the Holocene (< 0.5 Ma) rupture. The successive Holocene uplift along the Jhelum River and Ambore faults caused tilting of the upper and lower Chatter river traces. Seismic data computed by SSP, WAPDA, Mangla seismic network, indicate that the massive earthquake has reactivated the Jhelum Fault. Within two years of the massive earthquake more than 1500 seismic events (micro and macro) of magnitude ranging from 1.0 to 5.3 have been located along the JFZ area. The seismicity is observed to align not only along the mapped portion of JFZ, but also extends north and south of this mapped zone [12]. On March 10, 2006 an earthquake measuring 5.3 on Richter scale was felt with Intensity V at Mangla and VI in Mirpur. Around the epicenter its intensity was VII and was located at 33.19 N and 73.97 E, just 20 km east of Mangla. In the epicentral area of Afzalpur major cracks/collapses in buildings were reported. The Fault Plane Solutions (FPS) exhibited that the earthquake originated due to the seismic activities along the JFZ. It was followed by a series of aftershocks, five of them (M = 4.4, 4.5, 4.6, 4.6 and 4.8), were felt in and around Mangla/Mirpur with maximum intensity of IV on MMI. Later on June 02, 2006 an earthquake (M = 4.5) presenting a FPS like JFZ was felt around Mirpur with Intensity IV and III at Mangla. Even very recently during June 2007 two earthquakes of M > 4.5 having locations along JFZ were felt in Mangla and Mirpur. It is a clear indication of strain buildup along the JFZ. The presence of active mudflows after the massive October 08, 2005 earthquake, many located events and significant gap in seismicity along JFZ, suggest that the major earthquake (M = 6 to 8) can occur in near future. This earthquake will affect the areas along the JFZ, from Muzaffarabad to Mangla/Mirpur and Salt Range / Kalabagh. The future strain

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TABLE-1

MAGNITUDE FREQUENCY DATA JHELUM THRUST ZONE DURING 1960-2005*

Magnitude Number Of

Seismic Events Cumulative Number Of Seismic

Events greater than the given Mag. Cumulative Number Of Seismic

Events/Year (45 yrs period) 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 5.3 5.4 5.5

1 2 6 5

14 7

10 14 12 16 22 24 33 39 49 69 42 49 43 40 37 45 41 48 33 28 32 25 27 19 16 18 16 15 7

10 9

10 7 5 9 7 7 8 5 3 1 0 0 0 0

985 984 982 976 971 957 950 940 926 914 898 876 852 819 780 731 662 620 571 528 488 451 406 365 317 284 256 224 199 172 153 137 119 103 88 81 71 62 52 45 40 31 24 17 9 4 1 0 0 0 0

21.888 21.866 21.822 21.688 21.577 21.266 21.111 20.888 20.577 20.311 19.955 19.466 18.933 18.200 17.333 16.244 14.711 13.777 12.688 11.733 10.844 10.022 9.022 8.111 7.044 6.311 5.688 4.977 4.422 3.822 3.400 3.044 2.644 2.288 1.955 1.800 1.577 1.377 1.155 1.000 0.888 0.688 0.533 0.377 0.222 0.088 0.022 0.000 0.000 0.000 0.000

* Data before the mega earthquake of October 08, 2005. buildup, uplift rates, slip rates, recurrence intervals, and seismicity in the areas along the JFZ, need to be monitored continuously in order to avoid major human disaster like the October 08, 2005 earthquake. For this purpose the existing seismic networks in the area need to be upgraded and more instruments may be

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installed along future dams and allied structures. More Strong Motion Accelerographs (SMA’s) may also be got installed along existing and future critical structures. Most of the commercial/residential structures in Mirpur/Mangla and surrounding areas along the JFZ are not constructed according to Building Codes. New Building Codes have recently been approved by the Government of Pakistan and there is an urgent need for the implementation of the Building Codes in those areas. CONCLUSIONS The October 08, 2005 Kashmir Hazara earthquake originated along the Jhelum Thrust (JT), which is a recent offshoot of the Pir-Panjal Thrust (PPT). Field rupture observations indicate that it is not a blind fault as known before. Location of abnormal number of aftershocks till date verifies that the mega earthquake imposed increased stresses on the Indus Kohistan Seismic Zone and Jhelum Fault Zone, which can result in another major earthquake in the near future. The high rise buildings and Dams should be equipped with Strong Motion Accelerographs and Seismographs. New Building Codes should be implemented during future constructions carried out in the area. ACKNOWLEDGEMENT The author is thankful to all those colleagues who joined him during the post earthquake field studies. Also the observations and guidelines of seniors during the preparation of this work is highly appreciated and acknowledged. Most of the data used was obtained from online sources of ISC and USGS and also from the WAPDA Mangla, seismic observatory, where the author served as Deputy Director during the October 08, 2005 earthquakes and recorded the mega earthquake with most of the aftershocks till a period of twenty months. REFRENCES

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