The Kashmir Earthquake (October 8th, 2005), with a moment magnitude of Mw 7.6 occurred in the northwestern part of the Himalayas. The epicenter of the earthquake (34.476o N, 73.577o E) was 19 km from Muzaffarabad and 105 km from Islamabad (Fig. 1). The earthquake occurred along the Balakot-Bagh Fault which is a reverse fault that runs along the right bank of Jhelum River from Muzaffarabad to Naushara and crosses the Jhelum River to the west bank. The Kashmir earthquake represents the most devastating earthquake in South Asia in recorded history.1 An intense aftershock sequence followed the earthquake. On 9th October 2005, highest numbers of aftershocks (122) were recorded and by the end of 2005, a total of 1,778 aftershocks were recorded.2 Muzaffarabad and Balakot, the two most densely populated cities suffered most of the damage. The estimated death toll was around 87, 350, although it was estimated that the death toll could be over 100,000.2 The earthquake occurred within the Hazara-Kashmir Syntaxis along the Balakot-Bagh Fault (also known as Muzaffarabad fault) and the maximum vertical displacement on the fault was about 5 m.3 Thousands of very dense band of landslides were triggered as a result of the earthquake and the landslides resulted in destruction of infrastructure. The landslides were mostly triggered along the fault rupture trace. Hattian Bala rock avalanche was largest landslide associated with the earthquake which completely destroyed a village and blocked the tributaries of Jhelum River, thus creating a dam. A total of around 2500 landslides were triggered due to earthquake and mostly the landslides occurred along the hanging wall block of the fault.4
The greatest number of landslides occurred within sandstone and siltstone of Miocene age, Eocene and Paleocene Limestone and shale.4 The earthquake caused an economic loss of around 5 billion US dollars. The earthquake epicenter was located along the Kashmir Boundary Thrust (KBT) (NW-SE trending fault), which was reactivated during the Kashmir Earthquake.5
A 90 km long NW-SE belt of deformation was shown in the studies that were conducted through Synthetic Aperture Radar Data.6 The displacement was vertical and was from 1 m – 6 m north of Muzaffarabad.
The present case study is carried out to understand and learn the cause, vicinity areas and the impacts of landslides. Some recommendations are also made for minimizing the effects of landslides.
The study area is situated on the northwestern part of the Indian plate. The Indian plate is moving North-East at a rate of 5 cm per year and is being driven beneath Eurasian plate which is moving at a rate of 2 cm per year. Main Boundary Thrust and Panjal Thrust are folded to form an antiformal structure known as Hazara Kashmir Syntaxis (Fig. 1).7 The Muzaffarabad and Jhelum faults lie along the western limb of the Hazara Kashmir Syntaxis.8 The footwall of MBT comprises of tertiary clastics of Murree formation. Hazara Kashmir Syntaxis also comprises of siliclastics and dolomites of the Precambrian Muzaffarabad formation, Cambrian Abbottabad formation, and Paleocene Lockhart limestone and shale of patala formation.
Jhelum River and its tributaries (Neelum & Kunhar) drain the region. The rapid flow of these rivers have resulted in intense fluvial incision, thus producing steep lower valley slopes that have a gradient of > 50o.9 Between the Jhelum and Neelum river valleys, the mountains reach elevation of > 3000 m a.s.l.10
Landslides can be triggered by an earthquake, either by an increase in shear stress or due to decrease in soil strength. Significance of landslides depends upon location and magnitude of earthquakes but local conditions can also be of much importance. Earthquake triggered landslides have caused significant loss of life throughout history (Table 1).
The Kashmir earthquake triggered mass movements and these mass movements directly or indirectly caused approximately 26000 fatalities. The landslides that were triggered by the earthquake have an area of >7500 km2. Hazara-Kashmir syntaxis dominates the area and is enclosed by Main Boundary Thrust (MBT). The footwall of MBT is composed of Murree Formation.11 Other formations that are present in Hazara-Kashmir Syntaxis are Precambrian Muzaffarabad Formation (dolomites and siliclastics), Abbottabad Formation, Patala Shales and Lockhart Formation (Geological Map of the Area: Ghazanfar et al., 2010).12
Landslides in Murree Formation occurred alongside lower valley slopes. Landslides in Hazara Formation occurred in the fluvially incised slopes. Rockslides were extensive on the mid slope regions. Muzaffarabad Formation showed extensive fissuring.11
Owen et al., (2008)11 studied 1293 landslides and grouped them into six different geomorphic-geological settings. The study showed more than 90% of landslides were small (<1000 m2 in area) and were mostly in the form of shallow rock and debris falls from the top few meters of weathered bed rock and soil. Rock falls (<100 m2) and rock slides were common on ridge and spur crusts throughout the whole region. Slopes which have a gradient of < 20o and which were present on foot wall rocks of the MBT showed little evidence of landsliding. Landslides in Murree formation occurred along lower valley slopes which have a gradient >50o. The study also showed that the Precambrian Dolomites and siliciclastic rocks of Muzaffarabad formation were extensively fissured. Previous studies on the effects of large earthquakes in Himalayan region were carried out by Owen et al., (1995)13 and Barnard et al., (2001)14 showed that earthquake damage was concentrated on alluvial fans and on lower stretches of valley slopes.
Landslides that were triggered by the earthquake were concentrated in specific areas that were associated with geomorphology, lithology and human factors. More than half of landslides were in some way associated with road construction and human activity (Table 2).11 According to Keefer (1984)15 and Barnard et al., (2001)14, the modification of landscape by humans is the most essential factor for generating landslides in tectonic areas.
The number and extent of landslides in case of Kashmir earthquake exceeds that of 1991 Garhwal earthquakes11 (Owen et al., 2008). This shows that a specific earthquake magnitude threshold needs to be achieved in Himalayan setting to produce landslides in wide area and this threshold was achieved during Kashmir earthquake.11
Monsoonal climate persists in Muzaffarabad with annual precipitation of ~1500 mm. Snow falls at altitudes of >1500 mm during winter. The fissuring that was caused by Kashmir earthquake resulted in more landsliding in 2006 during monsoon period. The debris produced as a result of landslides was re-deposited by floods resulting in landscape modification.11
Sato et al., (2007)4 used black and white 2.5 m resolution SPOT-5 satellite imagery and mapped around 2400 landslides. They noticed that more than 80% landslides were small (< 0.5 ha) and 10% of landslides were large (> 1 ha). Landslides with large area mostly occurred on steep slopes with gradient <30o. It was also noticed that most of the landslides occurred on the hanging wall of the fault. < 30% of the earthquakes occurred on or within 1 km from the fault. Approximately 50% of landslides occurred within 2-3 km of the fault. The highest density (3.2 landslides / km2) of landslides was found near Balakot in Precambrian metamorphic and sedimentary rocks whereas the second highest density (2.9 landslides / km2) was recorded near Muzaffarabad in Eocene and Paleocene limestone.4 At a distance of 10-15 km from the fault, large landslides occurred on steeper slopes (40-45o), whereas at much greater distance of 20 km, large landslides also occurred on gentler slopes. Half of the landslides occurred in Miocene sandstones and siltstones.4
The land-cover classification using ASTER satellite imagery was carried out by Kamp et al., (2008)9 and it showed that the landslides covered about 2.4% of the study area. The most important landslide controlling parameter was bedrock lithology. It was observed that mostly the landslides occurred in highly fractured slate, shale, dolomite, limestone and clastic sediments of the Murree and Salkhala formations (Geological Map of the Area showing landslide distribution: Kamp et al., 2008)9. Almost one third of the landslides occurred alongside the rivers while one fifth of the landslides occurred alongside roads. It was also observed that most of landslides after Kashmir earthquake occurred in areas which were previously marked as potentially dangerous. According to Kamp et al., (2008)9, almost 90% of landslides occurred at elevations below 2000 meters while only 10% occurred between 2000 and 3000 meters (Table 3). In case of most of the landslides, the slope gradient was between 25o– 35o. It was observed that the most important parameter that controls landslides is lithology. 152 Landslides occurred in Igneous Rocks formations covering a total area of 224 km2 whereas 1941 landslides occurred in sedimentary rock formations covering a total area of 2292 km2.9
Areas that are underlain by Muzaffarabad, Murree and Panjal formations show highest landslide susceptibility to future failures. Formations that are in proximity to faults are also prone to future landsliding.
It is highly likely that the sites of earlier landslides may be activated and new landslides can occur along fissures especially after heavy rainfall. The ASTER 2005 Land Cover classification that was carried out by Kamp et al., (2008)9 showed that more than 50% of landslides (almost eight fold) occurred in grass/shrub lands which are more susceptible to landsliding. Destruction in Muzaffarabad city resulted directly from earthquake and landsliding. As a result, the alluvium of which the city is made of has a low vulnerability to future landsliding. Hazara formation has a low to moderate landslide susceptibility whereas the Murree formation has a moderate to high landslide susceptibility. Muzaffarabad formation and sites near the fault are prone to more landslides.9
According to Kamp et al. (2010)16, a six fold increase was observed in landslides from 2001 to 2009 and an eight fold increase was observed in landslide area. An inventory and susceptibility zoning map for landslides was prepared for the year 2001, which was considered as reference representing baseline landsliding. Studies conducted in 2001 and 2005 showed that the largest number of landslides occurred in Murree Formation with a nine fold increase whereas the limestone and Marble of Salkhala Formation and Panjal Formation showed second largest number of landslides with a six fold increase. Tanawal Formation showed a three fold increase in landslides with a highest increase in landslide density.
According to Sato et al., (2007)4 and Kamp et al., (2008)9; the total numbers of landslides produced as a result of Kashmir Earthquake were significantly less, as will be expected by an earthquake of similar magnitude.
Large extent of slopes were cracked within 5 km of the fault. In the years that followed, the amount of landsliding in Kashmir increased due to increase in precipitation. The rise in groundwater caused many slope failures.1 Many tension cracks were developed in the vicinity of the fault and have developed complex interlocking pattern of high density arrays with both bedrock and colluvium. Most of the landslides were located on the hanging wall block of the fault and landslides distribution was asymmetric. Within 5 km of the fault, large extents of slopes were cracked. Extensive slope cracking developed as a result of Kashmir earthquake. Prior to 2005 earthquake, the seismic activity in the study area was less significant due to which there were fewer cracks in slopes. After Kashmir earthquake, many tension cracks were developed in slopes. With more precipitation, the newly developed cracks will be filled with water and slope failure will occur. Extensive cracking on the hanging wall side of the fault shows that there will be many landslides in coming years.
According to Ghazanfar et al., (2010)12, high array of density cracks were developed on hill slopes both on hanging wall and footwall side of the fault and these cracks have the potential to fail. Through- out the Kaghan, Jhelum and Neelum valleys, the slope stability conditions were changed due to earthquake and it could result in more landsliding during monsoon periods or in case of another seismic activity.
According to Kausar et al., (2010)10, the earthquake resulted in deep seated and cut-slope failures and rock falls. The earthquake caused many cracks along hill slopes which are potential areas for future landslides. Landslides can occur by the increasing infiltration of water and generation of pore water pressures. Muzaffarabad, Bagh and Balakot were the largest cities that were affected by the earthquake. Landslides, rock falls, rock slides and debris flows were triggered in Jhelum, Kaghan and Neelum Valleys, some of which temporarily dammed the rivers. The white dolomites of Muzaffarabad formation failed in conjunction with red Murree formation silt and sandstones.
According to Dellow et al., (2007)17, the size and distribution of landslides due to Kashmir Earthquake was highly asymmetric. Three different areas of landslides can be classified;3. The third type of landslides were formed on the footwall side of the fault and were rare except within 2-3 km of fault trace
Studies by Saba et al. (2010)18 show that even before the earthquake, landslide activity was high. Although, landslides intensity increased after 2006 monsoon, the slope achieved stability afterwards and their intensity decreased.
Hattian Bala Rock Avalanche
The Hattian area is located in Jhelum Valley. The Kashmir earthquake reactivated a landslide south of Hattian. The slide has its origin from Dana Hill in the form of huge rock avalanche. The slide blocked the tributaries of Jhelum River (Karli and Tung tributaries) creating a natural dam (View of the source of the Hattian Bala rock avalanche (Dana Hill): Dunning et al., 2007.).19 Dandbeh Hamlet was buried by the slide and the reported deaths were around 1000.19 Researchers have suggested that during the Holocene two landslides may have occurred on Dana Hill which had supposedly left two scars, one of which was the cause of the Hattian slide.
The landslide has a total volume of approximately 85×106 m3; whereas, the affected area is about 1.8 km2. Falls and slides are a significant problem after an earthquake and they risk a population and infrastructure in lesser part of valleys.
Danna Hill lies on hanging wall of Muzaffarabad fault. The movement was favored by structurally controlled southeast plunging syncline.20 The deposit is mainly composed of clastic constituents of Murree formation which include sandstone, shale and mudstone. The slope failure was strongly controlled by lithology and tectonics and pre-existing rock slides. The study shows that due to inclined layering, the mudstones and sandstones of Murree formation are prone to slide.
The earthquake caused thousands of landslides and made many slopes unstable. Almost 26000 people lost their lives due to landslides only. The landslides were triggered by the main shock and later by aftershocks. Slope failure as a result of earthquake can only occur when a critical magnitude and peak ground acceleration is achieved as in case of Kashmir Earthquake. Muzaffarabad was the worst area affected by the earthquake. The earthquake resulted in deep seated cut slope failures and rock falls. The distribution of landslides was concentrated along precise areas related with geology and human impacts. Almost 90% of landslides were small and were in the form of rock and debris fall.4,9,11 More than half of landslides occurred in Miocene sandstones and siltstones of Murree formation.4,9 The dolomites and siliciclastic rocks of Muzaffarabad formation were extensively fissured. Landslides mostly occurred on steep slopes with gradient from 25o-35o.4,9,11 Major landslides occurred at elevation of around 3000 meters9. The Precambrian metamorphic and sedimentary rocks in the vicinity of Balakot showed highest landslide density. Muzaffarabad, Murree, Panjal formations and formations that are in proximity to the fault are prone to future landslides. Most of landslides occurred on hanging wall side of the fault and large extent of slopes were cracked in the vicinity of the fault. As 2005 was generally a dry year, groundwater was lacking and the cracked slopes could not develop into full failure but are susceptible to failure in case of another earthquake activity or under extreme weather conditions. The total number of landslides that occurred due to Kashmir Earthquake was significantly less as will be expected by a similar magnitude earthquake.4,9
Slope instability will increase as more forests are being converted to agricultural land and this instability during the event of an earthquake can cause landsliding. Ground shaking and structural failure were main reasons for triggering of Hattian Bala Rock avalanche. Most of landslides were small and only one the Hattian Bala landslide was major. The nature and accumulation of debris on eastern side shows that the debris moved at very high velocities.
A powerful 7.8 Mw earthquake occurred in Nepal on 25th April, 2015 and it was followed by a powerful 7.3 Mw earthquake on 12th May. Tens of thousands of landslides were triggered as a result of these two earthquakes. The landslides were triggered as far as Everest region. Many villages were affected by these landslides and hundreds of people lost their lives because of these landslides. Many more landslides can be triggered as a result of more aftershocks, gravitational failure and precipitation. Almost all of landslides were falls and slides of rock and soil. The landslides will pose serious hazard during ongoing 2015 monsoon season and 2016 monsoon season. These landslides are consistent with 2005 Kashmir earthquake landslides.21
Kashmir earthquake caused thousands of landslides and made many slopes unstable. The Kashmir area is highly prone to landslide hazards due to its geology and structures. Mass movements can easily be triggered by slight tremors in the region. Shaking from any major future earthquake will cause liquefaction of soil, hence causing the slope to lose cohesion. Older landslides can also be activated from earthquake induced landslides. Undercutting of slopes by river erosion and human activities are the main reasons for secondary failures. More than 50% of landslides were caused by human impacts like conversion of forest land, occupancy on exposed slopes and construction of roads. The landslides patterns are quantifiably related to ground motions. Co-seismic landslides occurred at regions with steep slopes and high roughness under the influence of strong ground motion. The study show that co-seismic landslides increases in regions close to epicenter and with increasing earthquake intensity. It is also worth noting that fissures and ground crack which were induced by main shock are still present and pose a potential threat for future landslides in case of another earthquake activity or under extreme weather conditions. The debris produced as a result of landslides was re-deposited by floods resulting in major landscape modification. The landslides patterns are quantifiably related to ground motions. Co-seismic landslides occurred at regions with steep slopes and high roughness under the influence of strong ground motion. The study show that co-seismic landslides increases in regions close to epicenter and with increasing earthquake intensity. Proper identification of various types of these movements is very essential for proposing their mitigation and preventing future loss of life and property. People may be warned not to construct in the vicinity of the rupture and avoid living at the foot of the mountains. If landslides hazards are not adequately mapped and mitigated with increasing commercialization and urbanization, the problems of landslides will greatly affect life and economy.
The authors have declared that no competing interests exist.
The 2005 Kashmir earthquake occurred at 08:50:39 Pakistan Standard Time on 8 October in Pakistan administered areas of Kashmir. It was centered near the city of Muzaffarabad, and also affected Pakistan's Khyber Pakhtunkhwa province and the Indian administered areas of Jammu and Kashmir. It registered a moment magnitude of 7.6 and had a maximum Mercalli intensity of VIII (Severe). The earthquake also affected countries in the surrounding region where tremors were felt in Afghanistan, Tajikistan and ChineseXinjiang. The severity of the damage caused by the earthquake is attributed to severe upthrust. It is considered the deadliest earthquake to hit South Asia since the 1935 Quetta earthquake.
Kashmir lies in the area of collision of the Eurasian and Indian tectonic plates. The geological activity born out of this collision, also responsible for the birth of the Himalayan mountain range, is the cause of unstable seismicity in the region. The United States Geological Survey (USGS) measured its magnitude as a minimum of 7.6 on the moment magnitude scale, with its epicentre about 19 km (12 mi) northeast of Muzaffarabad, Azad Kashmir, and 100 km (62 mi) north-northeast of the national capital Islamabad.
Most of the devastation hit north Pakistan and Pakistan administered Kashmir. In Kashmir, the three main districts were badly affected and Muzaffarabad, the state capital of Pakistan administered Kashmir, was hardest hit in terms of casualties and destruction. Hospitals, schools, and rescue services including police and armed forces were paralysed. There was virtually no infrastructure and communication was badly affected. More than 70% of all casualties were estimated to have occurred in Muzaffarabad. Bagh, the second-most-affected district, accounted for 15% of the total casualties.
The Pakistani government’s official death toll as of November 2005 stood at 87,350 although it is estimated that the death toll could reach over 100,000. Approximately 138,000 were injured and over 3.5 million rendered homeless. According to government figures, 19,000 children died in the earthquake, most of them in widespread collapses of school buildings. The earthquake affected more than 500,000 families. In addition, approximately 250,000 farm animals died due to collapse of stone barns, and more than 500,000 large animals required immediate shelter from the harsh winter.
As Saturday is a normal school day in the region, most students were at schools when the earthquake struck. Many were buried under collapsed school buildings. Many people were also trapped in their homes and, because it was the month of Ramadan, most people were taking a nap after their pre-dawn meal and did not have time to escape. Reports indicate that entire towns and villages were completely wiped out in northern Pakistan, with other surrounding areas also suffering severe damage.
- "...a second, massive wave of death will happen if we do not step up our efforts now", Kofi Annan said on 20 October with reference to the thousand remote villages in which people are in need of medical attention, food, clean water and shelter and the 120,000 survivors that have not yet been reached."
According to Pakistan's Interior Minister Aftab Ahmad Sherpao, Prime Minister Shaukat Aziz "made the appeal to survivors" on 26 October to come down to valleys and cities for relief, because bad weather, mountainous terrain, landslides and blocked roads are making it difficult for relief workers to reach each house and the winter snows are imminent."
In Islamabad, the Margalla Towers, an apartment complex in sector F-10, collapsed and killed many of the residents. Four deaths were reported in Afghanistan, including a young girl who died in Jalalabad, after a wall collapsed on her. The quake was felt in Kabul, but the effects were minimal there.
There were many secondary earthquakes in the region, mainly to the northwest of the original epicentre. A series of strong aftershocks occurred near Muzaffarabad. As of 27 October 2005 there had been more than 978 aftershocks with a magnitude of 4.0 and above that continued to occur daily. Since then, measurements from satellites have shown that mountain parts directly above the epicenter have risen by a few meters, giving ample proof that the rising of the Himalayas is still going on, and that this earthquake was a consequence of that.
Main article: International response to the 2005 Kashmir earthquake
The national and international humanitarian response to the crisis was extensive. In the initial phases of response, the Pakistan Medical corps, Corps of Engineers, Army aviation and a large number of infantry units played important roles. Lt. Gen Afzal, Maj. Gen. Imtiaz, and Maj. Gen Javid were the leaders of their formations. Maj.Gen Farrukh Seir was in charge of foreign relief co-ordination. The relief work in Jammu and Kashmir was led by IAS officers of the state administration, Bashir Runyal and Jaipal Singh. In early 2006, the Government of Pakistan organized a donors' conference to raise money for reconstruction and development of the area. A total of $6.2 billion was pledged and a large amount of the money was delivered in terms of services of international NGOs with high pay scales. The rest of the money pledged, which was given to the Government of Pakistan for reconstruction and development, was used by a reconstruction authority called Earthquake Reconstruction and Rehabilitation Authority, which was made by then military regime to accommodate retired high military officials and while keeping the command of the reconstruction and rehabilitation authority directly under the military. This authority has been highly criticised[by whom?] for luxurious non-developmental spending and false statistics. The basic infrastructure, including tertiary care, health, education, road networks, water supply, waste management and other basic needs, was still underdeveloped and had not reached pre-earthquake status in the region.
Well over US$ 5.4 billion (400 billion Pakistani rupees) in aid arrived from all around the world. US Marine and Army helicopters stationed in neighbouring Afghanistan quickly flew aid into the devastated region along with five CH-47 Chinook helicopters from the Royal Air Force that were deployed from the United Kingdom. Five crossing points were opened on the Line of Control (LOC), between India and Pakistan, to facilitate the flow of humanitarian and medical aid to the affected region, and aid teams from different parts of Pakistan and around the world came to the region to assist in relief.
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- Pathier, E.; Fielding, E. J.; Wright, T. J.; Walker, R.; Parsons, B. E.; Hensley, S. (2006), "Displacement field and slip distribution of the 2005 Kashmir earthquake from SAR imagery"(PDF), Geophysical Research Letters, American Geophysical Union, 33 (L20310), Bibcode:2006GeoRL..3320310P, doi:10.1029/2006GL027193
←Earthquakes in 2005→
† indicates earthquake resulting in at least 30 deaths