:: ASC :: Amateur Seismic Centre :: ASC :: Amateur Seismic Centre

:: ASC :: Amateur Seismic Centre

Website Guide   Home Recent Earthquakes 2011 M6.9 Sikkim

About Us | Quake Alerts | Search

Recent Earthquakes
Felt An Earthquake?

Historical Intensity Maps
South Asia Seismicity
Great Earthquakes
Tsunamis & Seiches
GSHAP Hazard Maps
Seismology Links
Be Earthquake Safe!

 

Advertisement

Advertisement


Advertisement

 

M6.9 Nepal-Sikkim, 2011

Date:

18 September 2011

Epicentre:

Near Kanchenjunga, Sikkim

Time:

12:40:48 UTC (18:10:48 IST)

Latitude:

27.723 N (PDE)

Longitude:

88.064 E (PDE)

Depth:

19.7 (PDE)

Magnitude:

Mw 6.9 (PDE); ML 6.8 (NSC)

Additional Info


Map Disclaimer


A strong earthquake (M6.0-6.9 termed as "strong") occurred in eastern Nepal near the Nepal-Sikkim border on 18 September 2011 at 18:10 IST. This earthquake has caused significant fatalities, widespread damage and landslides in many parts of eastern Nepal, Sikkim and north Bengal. It had a magnitude of Mw=6.9 and is the largest instrumented earthquake in this region. It is also possibly the largest earthquake to originate in this immediate region in historical record.

Aftershock advisory: Given the magnitude of this earthquake it would be reasonable to expect aftershocks in the M5.0-5.7 range. Aftershocks decay in magnitude and frequency with respect to the time elapsed since the mainshock. Thus the probability of these occurring reduces with time. That said, please bear in mind, large aftershocks can occur several weeks or months following the mainshock.

This earthquake was centred 11.5 kms NW of Kanchenjunga (Sikkim), India,
13 kms NE of Khunsa (Mechi), Nepal,
29 kms NNW of Dzongri (Sikkim), India,
40 kms WSW of Jathang (Sikkim), India,
52 kms NW of Mangan (Sikkim), India,
70 kms NW of Gangtok (Sikkim), India,
83 kms NNW of Kalimpong (West Bengal), India,
91.8 kms NNE of Ilam (Mechi), Nepal,
117 kms NNW of Shiliguri (West Bengal), India,
161 kms NNE of Biratnagar (Kosi), Nepal.

If you felt this earthquake (especially in western and southern West Bengal) please click here to view a felt map and to fill out a report.

At least 90 people were killed in this earthquake (10 AM IST, 28 September 2011). The largest number of fatalities occurred in India and amongst these the largest loss of life was in the state of Sikkim. Elsewhere in India, fatalities were reported in Bihar, Jharkhand and West Bengal. One fatality has also been blamed on this earthquake in Haryana. Deaths also occurred in eastern Nepal in the Kosi, Mechi and Sagarmatha divisions. Three fatalities also occurred in the Kathmandu valley. One person was also killed in Bhutan and seven in southern Tibet.

In Sikkim, major damage occurred in the district of North Sikkim  including in the Mangan-Chumthang area along with several significant landsides and rock falls. Modern buildings were heavily damaged at Chumthang and Jorthang. Media reports claimed a number of villages north of Mangan such as Sakyong have been entirely destroyed but this has not been verified. In the state capital Gangtok, the earthquake caused widespread panic with many running outdoors. A number of structures in the city were badly damaged and some precariously perched buildings completely collapsed down hillsides. Highways and other roads were blocked by landslides and rock falls. A number of deaths have taken place as a result of these throughout the state. This is possibly the most damaging earthquake in Sikkim since 1800.

In eastern Nepal, significant damage occurred in the divisions of Kosi, Mechi and Sagarmatha. The worst affected are the districts of Panchthar, Taplejung and Terathum where a number of public and private buildings have either sustained heavy damage or have been completely destroyed. Significant damage also extended into other districts such as Sankhusabha and Solukhumbu. Damage and fatalities also occurred parts of Dharan, Dhankuta and Ilam. The earthquake caused widespread panic across extensive parts of the east of the country resulting in very many injuries as people rushed out into the open. In the Kathmandu Valley, tremors frightened people outdoors and loose objects were knocked over. Isolated damage occurred at Bhaktapur, Lainchaur, Sankhu, Sundhara and Syachater. In Bhaktapur, the facades of a few buildings completely collapsed while at Lainchaur in the Kathmandu area, the perimeter wall of the British Embassy collapsed fatally. Damage was also reported from as far as Nuwakot and Sindhupalchowk districts. This is the most damaging earthquake in Nepal since the 1988 Udaypur Gahri earthquake.

Damage and fatalities also occurred in the Chumbi Valley in southern Tibet as well as in western Bhutan. In Tibet, as many as seven people were killed and over 200 hurt in the Galingang-Yadong area with damage extending into the adjoining districts of Dinggye and Gamba. In Bhutan, damage was significant in the Haa dzong, most notably in the Bji and Katsho gewogs where buildings including chortens and dzongs were either heavily damaged or partially collapsed. Damage also occurred in Chhuka, Dagana, Gasa, Paro, Thimphu and Samtse dzongs. Damage was also reported from central and eastern dzongs such as Samdrup Jongkar, Trashigang and Trongsa. In the capital Thimphu many people ran outdoors when the earthquake struck and a few buildings sustained minor cracks or lost pieces of plaster. Landslides and rock falls blocked many highways and mountain roads in the west of the country.

In north Bengal, the earthquake caused some damage, a few fatalities and many injuries in the Darjeeling, Jalpaiguri, Kalimpong and Siliguri areas. Many people ran outdoors and a number were struck by falling masonry. Damage also occurred in a number of tea estates in the region with at least one fatality was attributed to the complete collapse of a building in the Nideen Tea Estate. A levee was also damaged near Jalpaiguri. Severe tremors were felt in most parts of the region including at Alipurduars, Dim Dam, Mal Bazaar, Matabhanga and other places. This is the most damaging earthquake to have affected north Bengal since the 1930 Dhubri earthquake. Southward, damage was reported in West Bengal from Maldah, Murshidabad and Uttar Dinajpur. As far south as Kolkata, a few buildings developed cracks and people ran out of high-rise buildings.

Shaking from this earthquake has been felt over a large part of the Subcontinent including as far west as Ahmedabad, Ajmer, Jaipur and Indore in western India and as far south as Nagpur in central India. In lower Assam, the shock was severely felt with damage reported at Dhubri. Many modern apartment buildings were damaged in the city of Guwahati. Seismic seiches were observed in the Bramhaputra River in central Assam during the earthquake. In north-eastern India, the earthquake was felt at Itanagar in Arunachal Pradesh, at Dimapur, Mokokchung and Kohima in Nagaland, at Imphal in Manipur and at Jowai, Shillong and Tura in Meghalaya. Buildings developed cracks or isolated wall collapses occurred in the districts of north Bihar such as Araria, Madhubani, Katihar, Samastipur, Sitamarhi and Purnea. Damage and widespread panic also occurred in the districts of Bhagalpur, Munger and Patna. Similarly in Jharkhand, damage was reported from Dhanbad, Godda, Hazaribagh, Ranchi and north-eastern parts of the state. Shaking was relatively strong in many parts of eastern Uttar Pradesh including at Deoria, Ghazipur, Gorakhpur, Siddharthnagar and Varanasi. Westward it was felt lightly or by people in tall buildings in places such as Agra, Aligarh, Amethi, Farukhabad, Lucknow, Kanpur and Rai Bareili. In Madhya Pradesh, it was felt in districts adjoining Uttar Pradesh such as Bhind, Datia and Gwalior as well as in tall buildings in Bhopal, Jabalpur, Hoshangabad and Indore. In Chhattisgarh, the earthquake was strongly felt in the northern part of the state and caused minor damage in the Bilaspur area. In other parts of India, the earthquake was felt in tall buildings in the Bhubaneswar-Cuttack area in Orissa and in Delhi, Ghaziabad, Faridabad and Gurgaon in the NCR.

In Bangladesh, the earthquake caused panic in the northern districts in Rajshahi division. Many people were hurt in stampedes at places such as Gaibandha and Rangpur. Elsewhere, buildings sustained minor damage and isolated wall collapses were reported from Brahmanbaria, Bogra, Lalmonirhat, Natore, Nilphamari, Kishorganj and Panchagarh. In the capital Dhaka, people in tall buildings ran outdoors in panic. Minor damage is believed to have been sustained by a few high-rise buildings in the city. Southward, the shock was perceptible at places such as Barguna and Chittagong. Seismic seiches were observed in rivers in the Sunderbans.


If you felt this earthquake (especially in western and southern West Bengal) please click here to view a felt map and to fill out a report.

The USGS and GFZ mechanisms for this earthquake indicate strike-slip faulting. This is the strongest earthquake to have occurred locally in this region in the known historical record. The last Mw>6.0 earthquake in this region occurred on 19 November 1980 and had a magnitude of Mw 6.3. The 1934 Mw 8.1 Nepal-Bihar and the 1988 Mw 6.8 Udaypur Gahri earthquakes also caused significant damage in this region. Recently on 14 February 2006, a moderate M5.3 earthquake caused some damage and two fatalities in north-central Sikkim.
 

GFZ MOMENT TENSOR SOLUTION
Depth  30         No. of sta: 71
Moment Tensor;   Scale 10**19 Nm
  Mrr=-0.38       Mtt=-1.70
  Mpp= 2.09       Mrt= 1.23
  Mrp=-0.44       Mtp=-1.70
Principal axes:
  T  Val=  2.34  Plg=15  Azm= 77
  N        0.12      56      324
  P       -2.46      30      176

Best Double Couple:Mo=2.4*10**19
 NP1:Strike=309 Dip=80 Slip=-146
 NP2:       213     58       -11

 

           -----------           
        -----------------        
     ----------------#######     
    --------------###########    
  #####---------###############  
  ########----#################  
 ############################### 
###########----################# 
##########--------############## 
#########-----------#############
#########-------------###########
########---------------##########
 #######-----------------####### 
  #####--------------------####  
  #####---------------------###  
    ###---------   ----------    
     ##--------- P ---------     
        --------   ------        
           -----------           

References
01) National Earthquake Information Centre (NEIC), Golden, USA.
02)
Geo Forschungs Zentrum (GFZ), Potzdam, Germany.
03)
Macroseismic information has been compiled by the ASC from reports by local media and local NGO personnel.

Page Citation
Information on this page may be reproduced in print or electronically but it is requested that a citation be given to this website in the form of a link i.e. "www.asc-india.org".

Map Disclaimer
International boundaries of India (especially Arunachal Pradesh, Jammu & Kashmir, Himachal Pradesh and Uttarakhand) on the displayed map are from Google Maps. These do not conform to the external boundaries of India recognized by the Survey of India. That they are displayed on this page via Google Maps, is only for display purposes and this should not be misinterpreted as an endorsement of these boundaries by the Amateur Seismic Centre (ASC).

Page Updated: 28 Sep 2011 | Website Disclaimer

Amateur Seismic Centre, Pune,