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A
major earthquake
(M7.0-7.9 termed as
"major") occurred in the vicinity of the Nicobar
Islands on 13 June 2010 at 00:56 IST or 01:26 BST.
The earthquake had a magnitude of Mw=7.5
and has been very widely felt in the Indian sub-continent
causing at least one minor injury in Chennai. It did not generate
a tsunami although immediately following the earthquake tsunami
advisories were issued for much of the Bay of Bengal basin.
If you felt this earthquake, please let us
know!
The earthquake was
centred 139 kms SSW
of Chanumla (Teresa Island), India,
153 kms W of West Bay (Katchal Island), India,
187 kms SW of IAF Malacca Kakana (Car Nicobar Island), India,
233 kms NW of Campbell Bay (Great Nicobar Island), India,
446 kms SSW of Port Blair (South Andaman Island), India,
1404 kms ESE of Chennai (Tamil Nadu), India.
Shaking from this
earthquake was felt very strongly throughout the Nicobar Islands.
At Campbell Bay it was felt for nearly 10-seconds. People fled their homes in these islands and
sought shelter on higher ground fearful of a tsunami. Eyewitnesses
on Car Nicobar Island said the shock was of a comparable intensity
to the
Mw=9.1 Sumatra-Andaman earthquake on 26 December 2004. To
the north in the Andaman Islands, tremors were strong at Port
Blair where furniture was shaken for nearly 20-seconds. Many
people awoke and ran outdoors. Following the earthquake, a power failure cut electricity
supplies to Port Blair and the adjacent areas for half an hour adding to the panic. No damage or
casualties were reported from any where in the Nicobar Islands or
the Andaman Islands as a result of this earthquake.
Outside the Andaman &
Nicobar archipelago, this earthquake was felt widely in much of
Sri Lanka, in parts of Bangladesh, in Aceh, Indonesia as well as in
southern India and along the east coast of India. In Sri Lanka, tremors
were reportedly felt for as long as two minutes in some places.
Island wide it was felt at Anuradhapura, Badulla, Chilaw, Galle,
Kandy, Kantale, Matara, Negumbo and in parts of Colombo such as
Maradana and Wellawata. In Bangladesh, mild tremors were felt in
Bramanbaria, Chittagong, Comillah, Narayanganj as well as at
Baridara, Dhanmondi, Muhammedpur, Mohakhali and Uttara in the
capital, Dhaka. In Indonesia, the earthquake was strong and also
caused some concern at Banda Aceh, Aceh Besar and on Sabang Island
in Sumatra, Indonesia.
On the Indian
mainland, the earthquake was felt in parts of the states of Andhra
Pradesh, Karnataka, Orissa, Tamil Nadu and West Bengal. In Tamil
Nadu, strong tremors were felt in many parts of Chennai such as Adyar, Aminjinkarai, Anna Nagar, Ashok Nagar,
Avadi, Besant Nagar, Chintadripet, Choolaimedu, Gopalapuram,
Kilpauk, Kodambakkam, Korattur, Kottivakkam, Koyambedu, Mandaveli,
Mylapore, Nandanam, Nungambakkam, Pallavaram, Perungudi, Porur,
Royahpettah, Santhome, Sholinganallur, Teynampet, Thiruvanmiyur,
Triplicane, T-Nagar, Vadapalani and Vepery. People were woken up,
several ran outdoors, utensils and household objects were heard
rattling, loose objects were displaced, and in some instances
hairline cracks developed in walls and ceilings. In an isolated
incident a young boy was slightly injured as he and others ran out
of their apartment building in Besant Nagar. Elsewhere in the
state, tremors were felt at Vedaranyam and at many places in the
Kaveri basin.
In Andhra Pradesh, strong tremors were
felt in the districts of Chittoor, East Godavari, Krishna, Nellore, Srikakulam
and Vishakhapatnam. In the city of Vishakhapatnam, tremors were felt at Akkayapalem, Abid Nagar,
Gopalapatnam, Maddipalem, Narsimhanagar and Railway New Colony. The
occupants of high-rise buildings felt the strongest tremors and
many people ran outdoors despite heavy rains. In Vijayawada,
tremors were felt in Benz Circle, Moghulrajapuram, Singhnagar and
Veternary Colony. At Tirupati,
utensils and loose objects were heard rattling. Tremors were also
felt in the towns of Nagari and Puttur where people remained
outdoors until 3 AM. In Orissa, the earthquake was felt by the
occupants of high-rise buildings in the cities of Bhubaneswar and
Cuttack as well as in the district of Khurda. In West Bengal, the
earthquake was mainly felt on the upper floors of high-rise
buildings in Dum Dum and Jadavpur in the city of Kolkata. In
Karnataka as well, reports were isolated to people who were in the
upper floors of buildings in places such
as C.V. Raman Nagar and Sadashivnagar in Bengaluru.
Given the depth and magnitude of this earthquake the threat of a
tsunami existed and a regional tsunami watch was issued by the
PTWC for India, Indonesia, Malaysia, Myanmar, Sri Lanka and
Thailand. This was later downgraded to a local watch that was
limited to the Indian coastline by
the PTWC. The Indian tsunami warning centre, INCOIS, issued a
local watch for the Andaman & Nicobar Islands but later cancelled it
after no significant changes in sea level readings were recorded.
In India, tsunami warning sirens were reportedly sounded in the
Andaman and Nicobar Islands. In areas such as Carbyn Junction, on
the outskirts of Port Blair, the only warning available to
residents came from television news stations. In the Nicobar
Islands, residents fled to higher ground immediately after the
earthquake fearing a tsunami. Coastal areas in Chennai were
evacuated by local law enforcement agencies. However, many in the districts of Cuddalore,
Kanyakumari and Nagapattinam remained unaware of the tsunami
advisories until after day break later that same day. In Sri Lanka,
people in the cities of Kalutara,
Koralawela, Matara and Galle voluntarily headed inland and sough
refuge in churches, temples and schools that were situated on
higher ground. In Galle, intercity traffic was halted and some
buses were redirected inland as a safety precaution.
Villages were also evacuated in the Phangna province in Thailand.
This is the largest
earthquake in the Nicobar Islands since a
Mw=7.3 earthquake near
Teressa Island on 24 July 2005 in this immediate
region. A preliminary analysis of the focal mechanisms of both
earthquakes might suggest the same fault system was involved in
both events. At least nine significant aftershocks (M>4.5) were
recorded in the 24-hours following the Mw=7.5 mainshock including four of M>5.0. The number of aftershocks
diminish with time though the possibility of larger aftershocks
should not be ruled out. This latest earthquake and the earthquake
in July 2005 were both strike-slip in the type of faulting
involved. This would explain the lack of a tsunami though it needs
to be added that only a small percentage of earthquakes, regardless of type of
faulting, produce appreciable tsunamis. |
