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M7.6 Little Coco Island Earthquake, Myanmar


10 August 2009 *UTC*


W of Little Coco Island


19:55:38 UTC


14.013 N (NEIC)


92.923 E (NEIC)


33.1 kms (NEIC)


Mw 7.6 (NEIC), 7.5 (HRV)

Additional Info

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A major earthquake (M7.0-7.9 termed as "major") occurred in the Coco Channel between Myanmar and the Indian Andaman Islands, on 11 August 2009 local time. The epicentre of this earthquake was in Myanmar's territorial waters. It had a magnitude of Mw=7.6 and was widely felt in the region. Fears of a tsunami did not materialise and a tsunami watch that was initially issued for Bangladesh, India, Myanmar and Thailand was cancelled This earthquake is the largest earthquake in the Andaman & Nicobar Islands since the M9.1 Sumatra-Andaman earthquake in 2004 and is the largest known instrumented earthquakes in the Preparis Channel between North Andaman and the Irrawaddy delta. This is also the biggest earthquake within Myanmar since 1991.

If you felt either of these earthquake, please take the time to fill out a felt report questionnaire.

The earthquake was
centred 20 kms W of Little Coco Island (Ayerwaddy), Myanmar,
24 kms NNW of Landfall Island (Andaman Islands), India,
30.6 kms WSW of Great Coco Island (Ayerwaddy), Myanmar,
51 kms NNW of Diglipur (North Andaman Island), India,
78.3 kms N of Mayabander (Middle Andaman Island), India,
107 kms N of Rongat (Middle Andaman Island), India,
162 kms N of Port Blair (South Andaman Island), India,
175 kms SW of Seikkyi (Ayeyarwady), Myanmar,
288 kms SW of Yangon (Yangon), Myanmar,
354 kms W ot Tavoy (Tanintharyi), Myanmar,
580 kms S of Chittagong (Chittagong), Bangladesh,
637 kms ESE of Bhubaneswar (Orissa), India,
665 kms SSE of Bose International, Kolkata (West Bengal), India,
858 kms ENE of Chennai International, Chennai (Tamil Nadu), India,
1015 kms NE of Colombo, Sri Lanka.

Based on the location of this earthquake, there might be damage in the Coco Islands in Myanmar. No reports are available from Chinese naval installations on these islands. There were no casualties on North and Middle Andaman in the Andaman Islands, India. Minor damage has been reported to buildings at Diglipur and Rangat in the Andaman Islands. Loose objects were thrown down in homes and shops in many towns on North Andaman where the earthquake frightened everyone outdoors. Many people immediately sought refuge on higher ground fearing a tsunami.

The earthquake was also felt strongly at Port Blair on South Andaman Island. No information is available from the Nicobar Islands. Away from the Andaman & Nicobar Islands, the earthquake was felt strongly in the Irrawaddy delta including at Yangon where people were woken up. Tremors were also perceptible in other parts of Myanmar including at Nyapyidaw, Sittwe and Tavoy. In Bangladesh, the strongest tremors were felt in the Chittagong-Cox's Bazaar region while lighter tremors were felt in other parts of the country including at Dhaka. In India, the earthquake's effects were very pronounced along the Coromandel Coast where people were woken up or were frightened from Chennai in the south to Kolkata in the north including the cities of Bhubaneswar, Cuttack, Vijayawada and Vishakhapatnam . Tremors were also felt inland as far as Bengaluru, Hyderabad, Jamshedpur, Patna, Ranchi, Rourkela, Sambalpur and Shillong. Minor damage was been reported from isolated locations in India such as Bhubaneswar, Chennai, Cuttack, Rourkela and Vishakhapatnam. A dilapidated building collapsed in Tummagudem in Krishna district, Andhra Pradesh killing two people and although this was initially blamed on the earthquake, this claim was refuted with heavy rain being blamed instead. The earthquake was also felt in northern Aceh in Indonesia where it was strong enough to wake people up. According to felt reports received by the NEIC, tremors were perceptible as far as Bhutan, Cambodia, China (Hainan Island), Laos, Malaysia, Myanmar, the Maldives, Nepal, Singapore, Sri Lanka, Vietnam and Thailand.
If you felt this earthquake, please take the time to fill out a felt report questionnaire. This earthquake is also believed to have caused renewed volcanic activity on Barren Island.

A major tsunami was not generated by this earthquake in the Bay of Bengal. However, a small tsunami might have been generated that could have been recorded on tide gauges or observed by people on the ground. The mechanism of this earthquake suggests it nucleated within the subducting Indian plate or within the Burmese microplate as against on the interface between the Indian Plate and the Burmese microplate i.e. it was Intra-plate and not Inter-plate. This would be one of the reasons to explain the lack of a tsunami from this earthquake. Intraplate earthquakes along plate boundaries such as the Andaman-Sunda arc are not uncommon and have been noted along other subduction zones around the world e.g. off Gisborne, New Zealand (2007), Nisqually, USA (2001), off the coast of Peru (2001) and Oaxaca, Mexico (1995).

A tsunami watch was issued for the Bay of Bengal but was later lifted by the Pacific Tsunami Warning Centre in Hawaii. A tsunami alert were also issued by Bangladesh. The Indian tsunami warning centre, INCOIS, did not issue an alert. However, as news of the earthquake spread people living close to the sea at places such as Chennai, Cuddalore, Nagapattinam and Tirunelveli immediately began to seek the safety of higher ground. In Thailand, several villages were evacuated as a precautionary measure.

Several aftershocks have been recorded in the vicinity of the Coco Islands since the mainshock on 10 August 2009 (UTC). The strongest aftershock thus far was a Mw=5.8 earthquake that occurred 45-kilometres to the west of Little Coco Island at 09:21 UTC on 13 August 2009. It was strongly felt on much of North Andaman Island. Tremors were also felt in many parts of Chennai on the east coast of India.

01) National Earthquake Information Centre (NEIC), Golden, USA.
02) Harvard Centroid Moment Tensor Solution (HRV), Harvard, USA.
03) Pacific Tsunami Warning Center (PTWC), Ewa Beach, USA.
04) Indian National Centre for Ocean Information Services (INCOIS), Hyderabad, India..
05) Macroseismic information has been compiled by the ASC from reports by local media and local NGO personnel.

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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: 12 Sep 2009 | Website Disclaimer

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