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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.
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