A powerful earthquake of 6.8 magnitude jolted Bangladesh, northeastern India, Bhutan, Nepal and the adjoining region at 06.40 PM Sunday Bangladesh time that claimed over a dozen lives in India and Nepal while damaged a score structures in Bangladesh.
The epicentre of the earthquake was 68 km northwest of Gangtok, Sikkim, India, which is 508 km northwest of Dhaka, at about 20- km depth. There were three immediate aftershocks ranging from 4.0 to 5.5 magnitudes. People in Dhaka felt three severe jerks and feared the worst. There are no reports of loss of lives in Bangladesh so far.
This earthquake could be regarded as a warning for further strike of powerful earthquakes in the region and potential risks due to the characteristics of active seismic zone in the region and poorly built concrete structures [e.g. buildings; bridges; flyovers; roads].
Fewer people, about 300, were killed in Chile on February 27, 2010 although the magnitude of 8.8 was much stronger than the earthquake of 7.0 magnitude in Haiti on January 12, 2010 that claimed approximately 316,000 lives. It was due to the following of strict building code in Chile since the worst earthquake the country experienced in 1960.
According to the US Geological Survey (USGS), this region has experienced relatively moderate seismicity in the past, with 18 earthquakes of magnitude 5.0 or greater over the past 35 years within 100 km of the epicentre of the September 18 event. The largest of these was a magnitude 6.1 earthquake in November of 1980, 75 km to the southeast.
Bangladesh needed to learn from these earthquakes. The Government is required to undertake: (a) formulation of compatible standard of building code for all structures and strict monitoring of its implementation; (b) a national strategy to deal with earthquake; and (c) a preparedness program with inclusion of the tasks, in case of an earthquake, in curriculum, and a routine but effective countrywide earthquake drill [as well as fire drill] at least twice a year.
The USGS report on the 18 September earthquake stated in its tectonic summary that the 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 18 September 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.
You can find more relevant information from the following links:
A probabilistic seismic hazard map of India and adjoining regions:
Seismic hazard map of the region:
Shaikat Rushdee, a Political Analyst, Columnist/ Journalist and Broadcaster lives in Toronto, Canada, and works as Evaluation Editor at Cision Inc., world’s second largest media intelligence company.
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