ON THIS DAY 2001: Bhuj earthquake of 2001
A major earthquake struck Gujarat, India, on 26 January 2001 at 08:46 AM local time resulting in close to 13,823 deaths and extensive damage to property in Gujarat, India. Damage to a lesser extent also occurred in the adjoining states of Madhya Pradesh, Maharashtra and Rajasthan in India and in Sindh province, Pakistan. The earthquake had a magnitude of Mw=7.7 and was felt for several minutes in many parts of south Asia. This is one of the largest instrumented earthquakes in peninsula India.
The earthquake was centred 9.2 kilometres SSW of Chobari (Gujarat), India,
17.9 kilometres NNW of Bhachau (Gujarat), India,
44.0 kilometres NNE of Gandhidham (Gujarat), India,
46.7 kilometres NE of Anjar (Gujarat), India,
68.3 kilometres ENE of Bhuj (Gujarat), India,
86.9 kilometres NW of Morbi (Gujarat), India,
112 kilometres NNE of Jamnagar (Gujarat), India,
238 kilometres WNW of Ahmedabad (Gujarat), India,
292 kilometres SE of Hyderabad (Sindh), Pakistan,
371 kilometres SE of Clifton, Karachi (Sindh), Pakistan,
551 kilometres NW of Santa Cruz Airport, Mumbai (Maharashtra), India,
900 kilometres SW of Connaught Place, Delhi (N.C.R.), India.
Seismological | Damage - Gujarat, Outside Gujarat, Infrastructure | Liquefaction | Aftershocks
Seismological Aspects (Causative fault, blind thrust event, ground motions):
Slippage is believed to have occurred on the south dipping North Wagad reverse fault in the Kutch aulacogen or failed rift. This has been further confirmed by aftershock studies following the earthquake. Initial speculation held the Kutchh Mainland Fault (KMF) responsible, however, further studies and field observations show that it might have been caused on the previously unknown NWF lying in the vicinity of the KMF. Slip is believed to have totalled between 1 metre to 4 metres. The rupture is also believed to have approached within 9 to 15 kilometres of the ground surface. Earthquakes on unknown faults are not uncommon and have occurred in the best studied places, such as the 1994 Northridge earthquake in the heavily instrumented Los Angeles area. The earthquake is an intraplate event, as it occurred within the Indian plate, away from its edges. Others studies are also of the opinion that the earthquake occurred in the diffused western boundary of the Indian plate.
A surprising feature of this earthquake was the lack of a primary surface rupture, that usually accompanies events of such large magnitude. This implies that the earthquake was blind. Large blind earthquake have occurred elsewhere in the world, such as the M7.4 El Asnam, Algeria earthquake (1980) and the M8.1 Assam earthquake (1897). Widespread ground deformation in the form of lateral spreading and strike-slip faults were found as well as local upwarping. Strike-slip faulting was recorded near Bharodia and Manfara. Lateral spreading was observed at many locations. Much of the ground deformation was concentrated near the eastern edge of the rupture, north and north-east of Bhachau. Features of this nature are commonly observed after thrust-faulting earthquakes.
Violent ground shaking was felt in Bhuj for nearly 85 seconds with several minutes of lower level shaking. The duration of shaking at Ahmedabad and Surat was around 90 seconds and was felt for a similar length of time in other parts of India. A strong motion accelerograph in Bhuj failed to activate due to a cable failure, resulting in the loss of valuable scientific data. A similar instrument in the basement of the Passport Office building in Navrangpura, Ahmedabad recorded 0.098g. Using broad band velocities recorded by the IMD at Bhuj and a rupture model based on teleseismic data, an estimated value of 0.38g was obtained for Bhuj. Other studies used finite fault models coupled with a teleseismic rupture model to predict the peak ground acceleration and compared the results with a known set of Mercalli intensities derived from media reports for locations up to 700 kilometres away. Predicted values were 1-3 units lower that the observed Mercalli intensities and this can be interpreted either as local site response or a media bias. However, they predict 80% of g at distances up to 300 kilometres from the fault.
Violent ground shaking was felt in Bhuj for nearly 85 seconds with several minutes of lower level shaking. The duration of shaking at Ahmedabad and Surat was around 90 seconds and was felt for a similar length of time in other parts of India. A strong motion accelerograph in Bhuj failed to activate due to a cable failure, resulting in the loss of valuable scientific data. A similar instrument in the basement of the Passport Office building in Navrangpura, Ahmedabad recorded 0.098g. Using broad band velocities recorded by the IMD at Bhuj and a rupture model based on teleseismic data, an estimated value of 0.38g was obtained for Bhuj. Other studies used finite fault models coupled with a teleseismic rupture model to predict the peak ground acceleration and compared the results with a known set of Mercalli intensities derived from media reports for locations up to 700 kilometres away. Predicted values were 1-3 units lower that the observed Mercalli intensities and this can be interpreted either as local site response or a media bias. However, they predict 80% of g at distances up to 300 kilometres from the fault.
Shaking Effects (Within Gujarat):
The worst damage was caused in eastern Kachchh, in the vicinity of the town of Bhachau which was almost completely destroyed. Kachchh was cut off from the rest of the country for more than 24 hours. At Anjar, much of the old section of the town was destroyed. At least 143 students and teachers, who were participating in a Republic Day parade were killed at Khatri Chowk in Anjar, when buildings on both sides on the narrow lane they were in collapsed. The larger towns of Gandhidham and Bhuj were also badly affected. Many multi-storied buildings collapsed, including the housing quarters at the Indian Air Force base and the 8-storey Sahajanand Complex in Bhuj. The worst damage was concentrated in the old city of Bhuj. Jubilee Hospital, the main hospital in the city was levelled and so were many other medical facilities across Kachchh. Many of the injured were flown to Mumbai and Pune for medical treatment. Relief was flown in by the Indian Air Force, from its bases in Amritsar, Bhatinda, Chandigarh and Pune. Structures of historical importance such as the famous Aina Mahal and the Kachchh Museum were heavily damaged and partially collapsed. The Chhatris at the Bhuj Fort were also either completely destroyed or very badly damaged. The port of Kandla was closed following the earthquake. About 2,000 metric tones of Acrylonitrate (ACN), a highly toxic and flammable chemical leaked at the J.R. Enterprises Tank farm, Kandla. Another tank, containing HEP (Paraffin) in the same tank farm also leaked. Naphtha was released from a ruptured pipe at the Indian Oil Corporation (I.O.C.) tank farm. Ammonia was released at the Indian Farmer's Fertilizer Corporation Limited (I.F.F.C.O.) due to the loss of air conditioning. No fires were reported from industrial facilities. Sporadic damage occurred all across Gujarat. At Morvi, many historic buildings collapsed and heavy damage occurred at the famous Green Chowk market. The most significant damage however, occurred in the two large cities of Ahmedabad and Surat. In Ahmedabad, nearly 85 multi-storied buildings, such as the 10-storey Shikhar Apartments and the 10-storey Mansi Complex, collapsed killing 700 people. At least 60 students died when the 4-storey, Swaminarayan Vidhyalaya school collapsed in the Ghodasar-Isanpur area of Ahmedabad. Fires broke out at a few locations in Ahmedabad, like at the collapsed Sangemarmar Apartments. The famous Shaking Minarets in Ahmedabad were badly damaged. The Nehru Bridge and the Chimanbhai Bridge, across the Sabarmati River, suffered some damage. In Surat, a 7-storey building, the Harekrishna Apartments collapsed. 18 people were killed in stampedes in Surat's, Varachha and Wed Katargram areas.
The worst damage was caused in eastern Kachchh, in the vicinity of the town of Bhachau which was almost completely destroyed. Kachchh was cut off from the rest of the country for more than 24 hours. At Anjar, much of the old section of the town was destroyed. At least 143 students and teachers, who were participating in a Republic Day parade were killed at Khatri Chowk in Anjar, when buildings on both sides on the narrow lane they were in collapsed. The larger towns of Gandhidham and Bhuj were also badly affected. Many multi-storied buildings collapsed, including the housing quarters at the Indian Air Force base and the 8-storey Sahajanand Complex in Bhuj. The worst damage was concentrated in the old city of Bhuj. Jubilee Hospital, the main hospital in the city was levelled and so were many other medical facilities across Kachchh. Many of the injured were flown to Mumbai and Pune for medical treatment. Relief was flown in by the Indian Air Force, from its bases in Amritsar, Bhatinda, Chandigarh and Pune. Structures of historical importance such as the famous Aina Mahal and the Kachchh Museum were heavily damaged and partially collapsed. The Chhatris at the Bhuj Fort were also either completely destroyed or very badly damaged. The port of Kandla was closed following the earthquake. About 2,000 metric tones of Acrylonitrate (ACN), a highly toxic and flammable chemical leaked at the J.R. Enterprises Tank farm, Kandla. Another tank, containing HEP (Paraffin) in the same tank farm also leaked. Naphtha was released from a ruptured pipe at the Indian Oil Corporation (I.O.C.) tank farm. Ammonia was released at the Indian Farmer's Fertilizer Corporation Limited (I.F.F.C.O.) due to the loss of air conditioning. No fires were reported from industrial facilities. Sporadic damage occurred all across Gujarat. At Morvi, many historic buildings collapsed and heavy damage occurred at the famous Green Chowk market. The most significant damage however, occurred in the two large cities of Ahmedabad and Surat. In Ahmedabad, nearly 85 multi-storied buildings, such as the 10-storey Shikhar Apartments and the 10-storey Mansi Complex, collapsed killing 700 people. At least 60 students died when the 4-storey, Swaminarayan Vidhyalaya school collapsed in the Ghodasar-Isanpur area of Ahmedabad. Fires broke out at a few locations in Ahmedabad, like at the collapsed Sangemarmar Apartments. The famous Shaking Minarets in Ahmedabad were badly damaged. The Nehru Bridge and the Chimanbhai Bridge, across the Sabarmati River, suffered some damage. In Surat, a 7-storey building, the Harekrishna Apartments collapsed. 18 people were killed in stampedes in Surat's, Varachha and Wed Katargram areas.
Shaking Effects (Outside Gujarat):
Outside Gujarat, to the west, strong shaking was experienced in the Indus delta and in the large cities of Karachi and Hyderabad. 18 people were killed in the Sindh. A 7-storey building, Ghousia Apartments collapsed in the city of Hyderabad. Liquefaction, earthquake fountains and sandblows were also reported from here. In Rajasthan, many buildings were badly damaged, mainly at Bakhasar and Jodhpur. Many structures of historical importance, like the Jaiselmer Fort, were damaged in Rajasthan. Damage was also reported from Mt. Abu, Pokhran, Jodhpur, Jaipur and Udaipur. In Madhya Pradesh tremors were felt prominently in the Narmada Valley, as far as Jabalpur. In Maharashtra, buildings developed cracks at many places in Mumbai and Vashi. A fire brigade station suffered slight structural damage at Wadala, Mumbai. Tremors were felt strongly in Mumbai, Pune and as far as Kolhapur. Beyond these areas, the shock was felt to a limited extent in Hyderabad (Andhra Pradesh) and Bengalooru, and in high-rise buildings as far as Kolkata and New Delhi. Long period effects such as a sensation of nausea / giddiness among people and oscillating hanging objects were reported from many parts of India, Pakistan, Bangladesh and Nepal. Press reports from Bangladesh, reported unusual drifts in rivers in the Sunderbans following the earthquake. Even at locations over 1,000 kilometres from the epicentre, ground shaking was amplified in recent sediments resulting in locally moderate shaking. Such effects were experienced in the Kaveri delta of Tamil Nadu, in the Bengal basin and in the Kathmandu Valley in Nepal.
Outside Gujarat, to the west, strong shaking was experienced in the Indus delta and in the large cities of Karachi and Hyderabad. 18 people were killed in the Sindh. A 7-storey building, Ghousia Apartments collapsed in the city of Hyderabad. Liquefaction, earthquake fountains and sandblows were also reported from here. In Rajasthan, many buildings were badly damaged, mainly at Bakhasar and Jodhpur. Many structures of historical importance, like the Jaiselmer Fort, were damaged in Rajasthan. Damage was also reported from Mt. Abu, Pokhran, Jodhpur, Jaipur and Udaipur. In Madhya Pradesh tremors were felt prominently in the Narmada Valley, as far as Jabalpur. In Maharashtra, buildings developed cracks at many places in Mumbai and Vashi. A fire brigade station suffered slight structural damage at Wadala, Mumbai. Tremors were felt strongly in Mumbai, Pune and as far as Kolhapur. Beyond these areas, the shock was felt to a limited extent in Hyderabad (Andhra Pradesh) and Bengalooru, and in high-rise buildings as far as Kolkata and New Delhi. Long period effects such as a sensation of nausea / giddiness among people and oscillating hanging objects were reported from many parts of India, Pakistan, Bangladesh and Nepal. Press reports from Bangladesh, reported unusual drifts in rivers in the Sunderbans following the earthquake. Even at locations over 1,000 kilometres from the epicentre, ground shaking was amplified in recent sediments resulting in locally moderate shaking. Such effects were experienced in the Kaveri delta of Tamil Nadu, in the Bengal basin and in the Kathmandu Valley in Nepal.
Effect on public infrastructure:
The Atomic Energy Regulatory Board (A.E.R.C.) reported no damage from the nuclear power stations at Kakrapara (Gujarat), Rawatbhata (Rajasthan), Tarapur (Maharashtra), Narora (Uttar Pradesh), Kalpakkam (Tamil Nadu) and Kaiga (Karnataka). The Department of Atomic Energy (D.A.E.) said that the Kakrapara nuclear reactor, at Anumala, near Surat withstood the earthquake and was functional after the earthquake. The level of shaking is reported to have reached 51.2 Hz, very close to the tripping level. Several dams, such as the Suvi and Tappar Dams, were damaged in the epicentral area. Nearly 200 dams were damaged and required to either be repaired or strengthened. The intake tower of the Tapper Dam near Gandhidham was heavily damaged. Water supply was disrupted in Kutchh due to damage caused to the water pumping and pipe transmission system. Two elevated water tanks collapsed in the epicentral area, though 100 others survived without any major damage. 5 tanks also collapsed in the Maliya-Morbi area. Such a structure was seen swaying during the mainshock at Radhanpur. 16 out of 300 well inspected following the earthquake had sulphur problems. Highways were still functional. The Surajbari Bridge on National Highway 8A, suffered serious structural damage and traffic movement was restricted on it. A major power failure was experienced all over Gujarat immediately following the earthquake. The power stations at Wanakbori (1200 MW), Gandhinagar (450 MW), Dhuvaran (250 MW), AECO (380 MW), Panendro (110 MW), Sikka (110 MW) and Gandhar (90 MW) tripped. All 400 kV lines, except the 400 kV Indore-Asoj D/C and Jhanor-Padghe line tripped. Due to this, the frequency jumped from 49.86 Hz tp 5.15 Hz, causing a throw of 3500 MW in northern and central Gujarat and in Saurashtra. The Powergrid restored its lines within 13 minutes while the NTPC was done in 2 hours. Due to the immediate action by the Western Load Dispatch Centre of the Ministry of Power, a complete collapsed of the western grid (covering Gujarat, Maharashtra, Madhya Pradesh, Goa, Chhatisgarh and parts of Rajasthan) was prevented. Telecommunication networks were temporarily distrupted and the fiber optic lines severed. However, services were restored by within a week as was a cellular phone service.
The Atomic Energy Regulatory Board (A.E.R.C.) reported no damage from the nuclear power stations at Kakrapara (Gujarat), Rawatbhata (Rajasthan), Tarapur (Maharashtra), Narora (Uttar Pradesh), Kalpakkam (Tamil Nadu) and Kaiga (Karnataka). The Department of Atomic Energy (D.A.E.) said that the Kakrapara nuclear reactor, at Anumala, near Surat withstood the earthquake and was functional after the earthquake. The level of shaking is reported to have reached 51.2 Hz, very close to the tripping level. Several dams, such as the Suvi and Tappar Dams, were damaged in the epicentral area. Nearly 200 dams were damaged and required to either be repaired or strengthened. The intake tower of the Tapper Dam near Gandhidham was heavily damaged. Water supply was disrupted in Kutchh due to damage caused to the water pumping and pipe transmission system. Two elevated water tanks collapsed in the epicentral area, though 100 others survived without any major damage. 5 tanks also collapsed in the Maliya-Morbi area. Such a structure was seen swaying during the mainshock at Radhanpur. 16 out of 300 well inspected following the earthquake had sulphur problems. Highways were still functional. The Surajbari Bridge on National Highway 8A, suffered serious structural damage and traffic movement was restricted on it. A major power failure was experienced all over Gujarat immediately following the earthquake. The power stations at Wanakbori (1200 MW), Gandhinagar (450 MW), Dhuvaran (250 MW), AECO (380 MW), Panendro (110 MW), Sikka (110 MW) and Gandhar (90 MW) tripped. All 400 kV lines, except the 400 kV Indore-Asoj D/C and Jhanor-Padghe line tripped. Due to this, the frequency jumped from 49.86 Hz tp 5.15 Hz, causing a throw of 3500 MW in northern and central Gujarat and in Saurashtra. The Powergrid restored its lines within 13 minutes while the NTPC was done in 2 hours. Due to the immediate action by the Western Load Dispatch Centre of the Ministry of Power, a complete collapsed of the western grid (covering Gujarat, Maharashtra, Madhya Pradesh, Goa, Chhatisgarh and parts of Rajasthan) was prevented. Telecommunication networks were temporarily distrupted and the fiber optic lines severed. However, services were restored by within a week as was a cellular phone service.
Liquefaction Features:
Sandblows occurred over a wide area in Gujarat and were even reported from adjoining areas of Pakistan. A sandblow near Umedpur, 50 kilometres north of the epicentre, had a crater that was 10 metres by 5 metres across. Earthquake fountains were observed at Jamnagar. The furthest liquefaction was reported at Bharuch and Jambusar in south-eastern Gujarat. Liquefaction in the Great and Little Ranns was extensive. Water levels in the salt pans in the Little Rann rose dramatically and workers were forced onto the roads which were at a slightly higher elevation. Liquefaction covered an area of 10,000 square kilometres. Satellite images showed palaeo-channels and water bodies in the Great Rann. It was initially speculated in the press, that this was the reactivation of the Hakra river or the mythical Saraswati river, a view which was not shared by scientific data. Satellite images before and after the earthquake also showed the emergence of land, on the shores of the Gulf of Kutchh, around Kandla, a phenomenon which occurs only when there is a significant reduction in tidal waves activity. However, tidal height data from Kandla Port was not available following the earthquake. In the waters of the Gulf of Kutch and the Gulf of Khambat (also called Cambay) chlorophyll and suspended sediment concentrations rose and the fish catch off Daman in February was found to be double the normal value for that time of the year. A rise of 2.5 centimetres in the level of ground water was reported from Sola in Ahmedabad and Gandhinagar. The temperature of the hot springs at Ganeshpuri in Maharashtra's Thane district, rose from 35C to 75C. The level of the water also rose by three feet. Ground waves were also reportedly seen near Bhuj.
Sandblows occurred over a wide area in Gujarat and were even reported from adjoining areas of Pakistan. A sandblow near Umedpur, 50 kilometres north of the epicentre, had a crater that was 10 metres by 5 metres across. Earthquake fountains were observed at Jamnagar. The furthest liquefaction was reported at Bharuch and Jambusar in south-eastern Gujarat. Liquefaction in the Great and Little Ranns was extensive. Water levels in the salt pans in the Little Rann rose dramatically and workers were forced onto the roads which were at a slightly higher elevation. Liquefaction covered an area of 10,000 square kilometres. Satellite images showed palaeo-channels and water bodies in the Great Rann. It was initially speculated in the press, that this was the reactivation of the Hakra river or the mythical Saraswati river, a view which was not shared by scientific data. Satellite images before and after the earthquake also showed the emergence of land, on the shores of the Gulf of Kutchh, around Kandla, a phenomenon which occurs only when there is a significant reduction in tidal waves activity. However, tidal height data from Kandla Port was not available following the earthquake. In the waters of the Gulf of Kutch and the Gulf of Khambat (also called Cambay) chlorophyll and suspended sediment concentrations rose and the fish catch off Daman in February was found to be double the normal value for that time of the year. A rise of 2.5 centimetres in the level of ground water was reported from Sola in Ahmedabad and Gandhinagar. The temperature of the hot springs at Ganeshpuri in Maharashtra's Thane district, rose from 35C to 75C. The level of the water also rose by three feet. Ground waves were also reportedly seen near Bhuj.
Aftershocks:
The strongest aftershock occurred on January 28, 2001 and was centred near Bhachau. It had a magnitude of Mw=5.8 and caused widespread panic in Gujarat. People rushed out into the open in Ahmedabad where the aftershock was felt for 30 seconds. It was also felt at Jaiselmer in Rajasthan and as far away as Mumbai. Many people were injured at Ahmedabad, in an M5.3 aftershock on February 8, 2001, as they jumped from buildings in panic. An aftershock on February 24, injured several people in Sindh, Pakistan and caused some damage to buildings in the area.
The strongest aftershock occurred on January 28, 2001 and was centred near Bhachau. It had a magnitude of Mw=5.8 and caused widespread panic in Gujarat. People rushed out into the open in Ahmedabad where the aftershock was felt for 30 seconds. It was also felt at Jaiselmer in Rajasthan and as far away as Mumbai. Many people were injured at Ahmedabad, in an M5.3 aftershock on February 8, 2001, as they jumped from buildings in panic. An aftershock on February 24, injured several people in Sindh, Pakistan and caused some damage to buildings in the area.
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