September 18, 2011 Earthquake: Sikkim, Nepal, China, Bhutan, India

Reference #1053:

Felt Reports

At least 97 people killed, several injured, 5,000 displaced and 3,917 buildings and many roads and bridges destroyed or damaged in Sikkim, eastern Bihar and northern West Bengal; 6 people killed, 25 injured and at least 4,300 buildings destroyed or damaged in the Sankhuwasabha-Panchthar-Ilam area, Nepal; 7 people killed and 136 injured in Tibet, China; 1 person killed, 16 injured and at least 6,000 buildings damaged in the Paro-Thimphu area, Bhutan; minor damage to several buildings in Dhaka, Bangladesh. Total economic loss in India estimated at 22.3 billion US dollars. Electricity, telecommunications and water supplies disrupted and landslides and mudslides occurred in Sikkim, India, eastern Nepal and the Paro-Thimphu area, Bhutan. Felt (VII) at Gangtok and Shiliguri; (VI) at Jalpaiguri; (V) at Bandel, Baranagar, Barddhaman, Koch Bihar, Darjiling, Dispur and Guwahati; (IV) at Barakpur, Calcutta, Dhanbad, Durgapur, Haora, Iranagar, Muzaffarpur, Nagaon, Patna, Ranchi, Shillong and Tura, India. Felt throughout northeastern India, in much of northcentral India and as far as Bhubaneshwar, Bombay and Chandigarh. Felt (VI) at Damak; (V) at Biratnagar, Dhulikhel, Kathmandu and Pokhara; (IV) at Bhaktapur, Bharatpur, Patan and Tansen, Nepal. Also felt (VI) at Thimphu and (V) at Paro, Bhutan; (V) at Lhasa, China; (IV) at Barguna, Chittagong, Dhaka, Rajshahi and Sylhet, Bangladesh. Felt throughout Bangladesh and Bhutan and in much of eastern and central Nepal.

Tectonic Summary

The September 18, 2011 Sikkim, India earthquake occurred near the boundary between the India and Eurasia plates, in the mountainous region of northeast India near the Nepalese boarder. Initial analyses suggest the earthquake was complex, likely a result of two events occurring close together in time at depths of approximately 20 km beneath the Earth's surface. At the latitude of the September 18 earthquake, the India plate converges with Eurasia at a rate of approximately 46 mm/yr towards the north-northeast. The broad convergence between these two plates has resulted in the uplift of the Himalayas, the world's tallest mountain range. The preliminary focal mechanism of the earthquake suggests strike slip faulting, and thus an intraplate source within the upper Eurasian plate or the underlying India plate, rather than occurring on the thrust interface plate boundary between the two.

This region has experienced relatively moderate seismicity in the past, with 18 earthquakes of M 5 or greater over the past 35 years within 100 km of the epicenter of the September 18 event. The largest of these was a M 6.1 earthquake in November of 1980, 75 km to the southeast.

2.135 billion USD economic loss (reference #13727)

127 deaths (1 Bhutan, 7 China, 112 India, 7 Nepal); 441 injured (reference #1250)

The earthquake killed 94 peoples in north Sikkim, 06 in Bihar and West Bengal, 07 in Nepal and one person in China and displaced more than ~5,000 persons in Sikkim region. The economic losses estimated to be around 22.3 billion US dollars, out of which 70 % is attributed to the damage to the infrastructures like electricity, telecommunications and water supply.( reference #13730)

Taking the case of Sikkim earthquake-2011, in which more than 34000 building damaged and more than 400 landslides occurred, the total estimated loss is approximately $1.7 billion US. In addition about $200 million US damage was caused in Tibet (China), and slightly higher in Eastern Nepal in addition to losses in Bhutan with around 6000 buildings damaged.