The Telegraph
Friday , May 23 , 2014
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Night shake source in Bay of Bengal
- Faraway from coast, tremor in state because of epicentre’s shallow depth

Tremors baffled residents on Wednesday night. The Telegraph checks out the source of the shocks felt in Patna, around 700km from the epicentre in the Bay of Bengal

What happened on Wednesday night?

An earthquake in under the Bay of Bengal at 21.51.50 IST (9.51.50 pm) primarily triggered possible tsunami threat. Later, the earthquake monitoring agencies, including Indian National Centre for Ocean Information Services in Hyderabad that tracks all major undersea quakes, issued a bulletin at 10.11pm stating that the tremor posed “no tsunami threat to India”. In the landmass, the tremors were felt as far as Lucknow.

Where was the epicentre of the earthquake?

According to the data provided by US Geological Survey, the epicentre was in Bay of Bengal, around 275km southeast of Paradip port and 323km southeast of Bhubaneswar. The coordinates of the epicentre of the earthquake were 18.3°N (latitude) and 87.9°E (longitude).

What was the depth of earthquake at the epicentre?

10km below the earth’s surface.

What was the magnitude of the earthquake on the Richter scale?

According to India Meteorological Department (IMD), the magnitude of the earthquake on Wednesday night was 6 on the Richter scale. The magnitude is the measure of the energy released at the source of the earthquake as determined from measurements on seismographs.

What was the intensity of the earthquake?

The IMD categorised the intensity of the Wednesday night’s earthquake as “moderate”. The intensity measures the strength of shaking triggered by the earthquake at a certain location.

Were there any aftershocks?

Ashish Sen, director, IMD, Patna, said an aftershock was felt around 1.5 minute after the primary quake. The magnitude of the aftershock was 4.3 on the Richter scale.

What was the magnitude of the tremors felt in Patna and other parts of Bihar?

The IMD headquarters in New Delhi or any other earthquake monitoring agency did not release any official figure for the magnitude of tremors felt in Bihar. Sen claimed that the magnitude of tremors in the state must be less than 3 on the Richter scale. Places in south Bihar are expected to have received tremors of comparatively higher magnitude.

Why the tremors were felt in Bihar despite the earthquake’s epicentre being 700km away in the Bay of Bengal?

Sen attributed it to the shallow depth of the earthquake — 10km — at the epicentre. The shallower the depth of an earthquake, the wider is the impact.

What was the duration of the Wednesday night’ earthquake?

The IMD did not release any official figure about the duration of the quake but Sen said it must not have been more than three to four seconds.

Was there any causality?


Did the earthquake have any impact on the Mahabodhi Mahavihara in Bodhgaya?

Archaeological Survey of India denied any impact on the heritage site.

How earthquake-prone is Bihar?

Districts like Araria, Darbhanga, Madhubani, Sitamarhi and Supaul lie in Zone V — very high-risk zone for earthquake. The south-western districts of Aurangabad, Bhojpur, Buxar, Gaya, Jehanabad, Kaimur, Nawada and Rohtas lie in Zone III — moderate earthquake zone. The remaining districts of Bihar, including Patna, lie in Zone IV — high-risk zone.

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