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A Preliminary Geoseismological Report on Kashmir Earthquake of 8th October 2005

Geological Survey of India, Northern Region

A devastating earthquake shook the western Himalaya and adjoining regions on the morning of 8th October 2005, inflicting very heavy casualties in a large area, particularly belonging to the Pak Occupied Kashmir (POK). This deadliest of the Himalayan earthquakes recording a magnitude of 7.6 took a toll of thousands of human lives and rendered millions homeless. The human death figure on the Indian side of the LOC crossed 1300 where as in the POK it is reported that nearly 50,000 people perished in the catastrophe. The epicentre of the event was located in the Kishanganga (Neelam) valley, north of Muzaffarabad in POK, some 125 km WNW of Srinagar (Fig.1). The USGS web site gave the following parameters of the 8th October main event on 8th October 2005. Date: 05/10/08 Origin Time: 03: 50: 38.63 (UTC) Epicentre: 34.432°N: 73.537°E Mw: 7.3 Depth: 20 km Best Double Couple Solution Seismic Moment: Mo = 1.0 x 1020 Nm NP1: strike = 358°, dip = 29°, slip = 140° NP2: strike = 124°, dip = 72°, slip = 67° The USGS recorded 22 aftershocks of M ≥ 4.5 in the first eighteen hours of the main shock. IMD Parameters Origin Time:03 hr 50 min 35.8 sec Epicentre: 34.6°N:73.474°E Magnitude: 7.4

The Broadband Seismological Observatory of GSI at Jabalpur also recorded the main event and evaluated the origin time as 03 hr 50 min 56 sec.

The short period MEQ digital recorders stationed at GSI Office, Chandigarh for purpose

of seismic microzonation of the urban complex gave the following attributes of the earthquake. Arrival time of P-wave: 03: 51 : 51.27 (GMT) Time gap between arrival of P and S waves (S-P): 55.08 seconds Signal duration at Chandigarh: 15 minutes Epicentral distance of the earthquake from Chandigarh: 496 km (approx).

A three-station MEQ network operating at Chandigarh recorded as many as 160 aftershocks till 11.30 hrs of 10.10.2005. A TV News Channel of Pakistan reported occurrence of 575 aftershocks between 8th and 14th October 2005. The date-wise distribution of numbers of the aftershocks during this period was 102, 122, 75, 76, 63, 78 and 59, respectively.

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The Geological Survey of India, Northern Region has taken up the investigation of the earthquake in a big way. Officers from Operations P&H.P, J&K and Uttaranchal, apart from Earthquake Geology and Landslide Hazard Studies Divisions, have been pressed in to service to collect data pertaining to the effects of the earthquake from different places with the main objective of constraining the isoseismals of this mega seismic event. It is planned to establish an array of three short period digital MEQ seismographs in the Kashmir valley to record the aftershock activity, which has so far been very prolific. A number of M ≥ 5 aftershocks, which can be felt even at far off places, are still occurring at quite a regular interval. Seismotectonic Setup

The epicentre of the earthquake is located in the Frontal Himalayan Belt and is bounded in the north and east by the Main Boundary Thrust (MBT) and in the west by Jhelum and Shinkiari Faults (Fg.1). Represented by the cover rocks of the Frontal Belt affected by fold-thrust movements during the terminal phase of Himalayan orogeny, the epicentral tract lies in the Jhelum re-entrant, which is the outer reflection of the Great Western Himalayan Syntaxis. Jhelum fault is a prominent N-S trending tectonic discontinuity showing left lateral movement. It separates the Kashmir and Peshawar tectonic basins and has registered neotectonic activity. The Shinkiari fault is a sub-parallel neotectonic feature marking the eastern boundary of the Peshawar basin. It is to be mentioned here that one of the nodal planes of the USGS fault plane solution of the 8th October 2005 earthquake has almost a N-S strike, paralleling the Jhelum-Shinkiari fault system.

The last 120-year database on the seismicity of the region indicates occurrence of many earthquakes of M ≥ 4 in the Kashmir basin. Of these, the earthquake of 30th May 1885, with its epicentre located 19.5 km west of Srinagar, was the most powerful. This earthquake caused widespread damage, in which 3000 human lives were lost. The 2nd September 1963 Badgam earthquake of Mb 5.1 also caused some low order damage in the Kashmir valley. Damage Survey in Kashmir Valley

The epicentre of the earthquake is located north of Muzaffarabad in the Neelam valley in the POK. As per the reports, the damage has been of a very high order in the Muzaffarabad-Balakot sector, where thousands of people are reported to have perished. During the course of the present survey some 15 localities were visited in the Kashmir valley to observe the effects of the earthquake. The place wise description follows. Srinagar Town

The tremors, accompanied by a whizzing sound, were very strong at Srinagar town. There was lot of panic all around and some, particularly women and children, remained traumatized for days. It was difficult to stand, so people sat down, and some, to maintain balance, kneeled on the ground. During the earthquake, those driving two or four wheelers felt the shocks and immediately came to a halt in panic.

At Srinagar, damage to the buildings and other civil structures were not significant. In Batmaloo area, partial collapses of a few old and weak brick walls could be seen (Photo 1). In a very old building constructed of unbaked bricks with timber reinforcement, a staircase collapsed. In the Hazaratbal Shrine a few marble face stones got peeled off from a burzi under the influence of the strong tremors (Photo 2). Cracks appeared in many structures in the down town area. Grade 1 cracks could be seen in some well-constructed buildings as well. The Shankaracharya Temple, situated over a Panjal Volcanics hilltop, remained unscathed. This

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ancient structure, repaired and renovated in parts in recent times, is founded over solid bedrock and is constructed of large tabular basalt blocks having very good shear strength. It was perhaps the type of construction, which prevented any damage from taking place in a zone of fairly high intensity of shaking. In Srinagar town, most of the new constructions are generally of two stories and have used reinforced bricks with sand-cement mortar in the walls and G.I. sheets in the slanting roofs. These structures escaped without any significant damage. Baramula Town

The town of Baramula is located on the banks of Jhelum River over Karewa deposits, comprising sand, silt and clay. The tremors, accompanied by a sound of blowing storm, were very distinct, instilling a deep sense of fear among the residents. The tremors were described to be having a predominant E-W horizontal direction of vibration under whose influence several of the civil structures came under distress. Some of the low compound walls, constructed of stone masonry packed in mud mortar, failed during the earthquake. A few of such buildings also suffered partial collapse. Many of the buildings developed cracks and plaster peeling off from places. A portion of a well-constructed, two story brick structure, housing the Dayal Furnisher Show Room, caved in and the ground floor brick wall developed gaping diagonal shear cracks (Photo 3). It appears that the lean brick columns supporting the rather heavy structure were not capable of withstanding the strong horizontal seismic loading, and thus failed. The building is founded on silty soil where groundwater occurs at a depth of 7.5 m. Rampur-Uri Sector

As one proceeded west of Baramula, a perceptible increase in the intensity of ground motions was witnessed. The gate of Rampur Garrison was found sheared with its plaster peeled off at places. Further ahead along the Muzaffarabad highway, the ancient temple of Buniyar, also known as Pandav Temple, constructed in the 12th Century AD by the Rulers of Avantivarman Dynasty, suffered some conspicuous damage on account of the earthquake. From its high front portal, some of the large interlocking blocks of granite slipped off and were seen strewn by the side of the road (Photo 4). The sanctum sanctorum of the rather dilapidated temple developed gaping cracks.

The Datta Mandir near Mohura of a similar architecture as that of Buniyar temple but constructed of large blocks of metavolcanics suffered partial collapse in one corner (Photo 5). The pitched stones from the retaining walls were also dislodged. The dwellings of the nearby settlements were appreciably damaged and their inhabitants had shifted in makeshift tents adjoining the Temple precincts.

The failure of terrace slopes of Jhejum valley was first spotted near Mohura (Photo 6).

Near Bandi, a debris slide that blocked the Highway was triggered by the strong tremors of 8th October 2005.

At Uri, there was a clear accentuation in the intensity level as from here onwards, most of the structures suffered Grades 4 and 5 damage (Photo 7). In this intensity zone, large-scale collapse of the dwellings and fairly intense coseismic slope failures were responsible for a number of deaths and injuries. Uri-Kamalkot Sector

The village of Salamabad, situated about 6 km from Uri along the Muzaffarabad Highway, was totally destroyed by the earthquake. Here, most of the structures, constructed of

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stone masonry packed in mud or weak sand-cement mortar with sloping G.I. sheet roofing suffered total collapse corresponding to Grade 5 of the MSK-64 scale (Photo 8). The bunkers (low mud masonry structures) and the abutments of bridges/culverts came under high distress in this sector. In the region comprising shale and sandstone bands of Murree Group a number of coseismic landslides developed, which blocked the Highway and the roads at several places. On the day of the visit on 12th October 2005, the Muzaffarabad Highway was still blocked by a series of huge landslides a little ahead of Salamabad (Photo 9). It was reported that a number of persons were killed or injured by the triggered landslides.

In Lachi and Sultan Taki villages, the damage was near total with heavy loss of life in

most of the settlements (Photo 10).

The damage was equally severe in the village of Kamalkot and the surrounding hamlets situated at the foot of a high mountain Range, about 25 km from Uri. The inhabitants who were interviewed narrated that an explosion like sound accompanied the powerful shocks, never experienced before. They further stated that there was dust all around and on regaining composure realized that their world was lost. There were several who were killed instantly and many buried under tons of debris. In all these settlements the dwellings were constructed in the typical style with heavy stone masonry walls of low shear strength and sloping G.I. sheet roofing. Nearly all such structures were reduced to heaps of rubble (Photo 11). From a distance the dwellings appeared like canopies of glimmering sheets placed over the ground (Photo 12).

In two of the rivulets of the area, the discharge increased several folds as a few new springs opened up (Photo 13). In one of the nalas that cut across the Kamalkot road, the water discharge turned blackish in colour and was depositing the fines on its sides at the break of slopes. The nala originated from carbonaceous shale bed representing the contact of the Main Boundary Thrust (MBT). It appears that due to the earthquake a new spring opened up in this zone, which was eroding away the pulverized and weak mass of the fault zone and carrying the sediments along with the swift flow (Photo 14). Whether this phenomenon was related with some coseismic tectonic movement along the MBT, is yet to be established. Seismic Intensity Distribution

The 8th October 2005 Kashmir earthquake was a major seismic event of the Himalaya recording a magnitude of 7.6 on the Richter scale. The tremors were felt up to a distance of 1000 km from the epicentre and the damage extended in a radius of around 140 km. As per the reports gathered from print and electronic media sources, the intensity in the epicentral tract (in P.O.K.) appears to be of the order of X on the MSK-64 scale. This zone seems to encompass the localities of Muzaffarabad and Balakot and has a N-S elongation pattern. In this zone majority of the structures suffered Grade 5 damage, hugh landslides generated and even heavy objects overturned. In the Uri-Salamabad-Kamalkot sector the seismic intensity was certainly IX. It is very apparent that the low shear strength structures using the locally available stones and a weak bonding matrix fail miserably under this intensity. Reports from Tangdhar area in Kupwara district, J&K also indicate of intensity IX damage. East and south of Uri the seismic intensity was of the order of VIII, which extends up to Baramula in the east and Poonch in the south. Srinagar town comes in intensity VII as per the present survey (Fig.1). Reports of earthquake investigation from the Jammu region are awaited, after which the intensities will be assigned in that sector.

The degree of shaking in Himachal Pradesh and North Punjab was also quite high

though damage to structures occurred only in stray cases in this intensity. In Chandigarh, most

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of the people felt the tremors and some came out in the open. Hanging objects like fans swung, liquids in containers spilled and some objects rocked. There was some commotion but more of inquisitiveness. In Delhi also the tremors were quite distinct and felt by many. People residing in the upper floors felt the vibrations more strongly and came down after realizing that it was an earthquake. In Faridabad, Noida and Gurgaon, the effects were similar. In Lucknow, only those who were residing in G+4 floors felt the tremors. On a preliminary estimate the intensity here would have been II/III on the MSK scale (distance from epicentre 1075 km).

Table 1: Location-wise intensity in Srinagar-Uri-Baramula sector

Location Intensity Srinagar VII Batmalu VII Baramula VII Chahalam VII Rampur Cantt. VIII Pandav Mandir, Bunihar VIII Data Mandir VIII Mohura VIII Uri IX Salamabad IX Lachi village IX Sultan Taki village IX Kamalkot IX

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Figure 1: Isoseimal (tentative) of 8th October 2005 Kashmir Earthquake [MSK - 64 scale]

Basemap source: Seismotectonic Atlas, GSI 2000

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Photo 1: Partial collapse of a brick wall packed in mud mortar at Batmaloo, Srinagar.

Photo 2: Peeled off marble face stones from a burzi of Hazratbal shrine, Srinagar.

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Photo 3: Gaping shear cracks in ground floor brick wall and collapse of eastern portion of the building housing Dayal Furnishers at Baramula.

Photo 4: Slipping off of large tabular granite blocks from the portal of Bunihar temple.

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Photo 5: Partial collapse suffered by Datta mandir near Mohura.

Photo 6: Failure of terrace slopes on right bank of Jhelum River near Mohura.

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Photo 7: Heavy collapses suffered by two storey army barracks at Uri Cantonment.

Photo 8: Total collapse of structures at Salamabad village.

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Photo 9: Blockade of Muzaffarabad highway, 5 km ahead of Salamabad by coseismic landslides.

Photo 10: Grade 5 damage to a conventional two-storey house at Sultan Teka village.

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Photo 11: A heavily damaged masonry structure at Kamalkot village.

Photo 12: Total collapse of a dwelling at Kamalkot village.

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Photo 13: Grade 5 damage to structures at Kamalkot. A stream seen in the background has been created by opening of a spring consequent to the earthquake.

Photo 14: The Main Boundary thrust (MBT) marked by black coloured carbonaceous

material. This tectonic discontinuity seems to have been disturbed by the

earthquake motions.