Understanding the M6.9 Sikkim earthquake


A magnitude 6.9 earthquake hit Sikkim, India at 12:40 UTC on September 18, 2011, at a depth of 20.7 km. The earthquake caused victims and huge damage in Sikkim (India), India and Nepal. It was also well felt in Bangladesh.

The quake occurred near the boundary between the India and Eurasia plates, in the mountainous region of northeast India near the Nepalese border. Initial analysis suggests 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. (USGS)

The collision with the Eurasian Plate along the boundary between India and Nepal formed the orogenic belt that created the Tibetan Plateau and the Himalaya Mountains, as sediment bunched up like earth before a plow.

The Indian Plate is currently moving northeast at 5 cm/yr (2 in/yr), while the Eurasian Plate is moving north at only 2 cm/yr (0.8 in/yr). This is causing the Eurasian Plate to deform, and the India Plate to compress at a rate of 4 mm/yr (0.15 in/yr).

The ministry has set up at least 16 earthquake monitoring laboratories in Sikkim and North Bengal, which are monitored by faculty and students of the .

The data recorded in these laboratories has been able to pinpoint that the epicentre lay 35 kilometres beneath the earth’s surface and the quake could be categorized as one of the strike-slip movement type that came with a single big jerk and three smaller aftershocks. The ground just above the epicentre felt a jerk of .45g. The report says that Gezing, another place in Sikkim, felt a tremor of the magnitude of .3g, Lingja followed next with .28g and Mangan .24g. (TOI)

“The epicentre of the tremor lies just below the Kanchanjungha liniament or hidden fault, making it extremely earthquake prone,” said Shankar Nath, head of the geophysics department who is also the lead scientist of the project.

Earthquake hazard in NorthEast India – A seismic microzonation approach with typical case studies from Sikkim Himalaya and Guwahati City (IAS-AC)

The AstroCartoGraphy map for the earthquake shows Venus, Uranus, and Pluto all angular at the epicenter. Venus has been translating the epic Uranus-Pluto square of revolution and evolution, and these are sharply focused in the earthquake chart. Uranus is rising, Venus is setting, and Pluto is culminating. These simultaneous angularities are know as parans. Pluto just stationed-direct on Sept. 16 so is virtually stationary now, and thus it's power is concentrated. (StellarInsight)

Sunday's earthquake reached the comparatively safer seismic zones of South Chotanagpur plateau, besides generating cracks in buildings and roads in different parts of the state, and exposed the lack of preparedness of the state administration in handling such eventualities. Once the panic of tremors started subsiding by late evening, rumour mills started working and hundreds of people came out in the open late in night after some anonymous SMSes and phone calls circulated in capital predicting another shock at 11.30 PM. (TimesOfIndia)

Rescue teams backed by army sappers using explosives tried to force their way on Tuesday to the remote epicentre of a powerful Himalayan earthquake that killed 67 people in India, Nepal and Tibet. Before the grim search for more victims can even begin, the main challenge is to reach the isolated, mountainous impact zone on the border between Sikkim and Nepal after Sunday's 6.8 magnitude quake. (HindustanTimes)

If you value what we do here, create your ad-free account and support our journalism.


Your support makes a difference

Dear valued reader,

We hope that our website has been a valuable resource for you.

The reality is that it takes a lot of time, effort, and resources to maintain and grow this website. We rely on the support of readers like you to keep providing high-quality content.

If you have found our website to be helpful, please consider making a contribution to help us continue to bring you the information you need. Your support means the world to us and helps us to keep doing what we love.

Support us by choosing your support level – Silver, Gold or Platinum.

Other support options include Patreon pledges, one-off payments using PayPal and purchasing products from our webshop.

Thank you for your consideration. Your support is greatly appreciated.

Teo Blašković

$5 /month

  • Ad-free account
  • Clean user interface and fast browsing
  • Direct communication with us via chat and email
  • Suggest new features, content and applications
  • Early access to new apps and features

$50 /year

$10 /month

  • Ad-free account
  • Clean user interface and fast browsing
  • Direct communication with us via chat and email
  • Suggest new features, content and applications
  • Early access to new apps and features

$100 /year

$25 /month

  • Ad-free account
  • Clean user interface and fast browsing
  • Direct communication with us via chat and email
  • Suggest new features, content and applications
  • Early access to new apps and features

$200 /year

You can also support us on Patreon

support us on patreon

or by sending us a one-off payment using PayPal:

Commenting rules and guidelines

We value the thoughts and opinions of our readers and welcome healthy discussions on our website. In order to maintain a respectful and positive community, we ask that all commenters follow these rules:

  • Treat others with kindness and respect.
  • Stay on topic and contribute to the conversation in a meaningful way.
  • Do not use abusive or hateful language.
  • Do not spam or promote unrelated products or services.
  • Do not post any personal information or content that is illegal, obscene, or otherwise inappropriate.

We reserve the right to remove any comments that violate these rules. By commenting on our website, you agree to abide by these guidelines. Thank you for helping to create a positive and welcoming environment for all.


  1. This EQ is just on the border of the north indian with the eurasian plate. A proof of the movement caused by the African plate pushing the small indian plate against the eurasian. Always it has been said that the indian subcontinent came from eastern Africa like the derive of the continents theory explain until now. At the present in time we see how this movement never end rising, the Himalayas. Or there is other explanation……… Perhaps.

Leave a reply

Your email address will not be published. Required fields are marked *