A tsunami watch has been issued to 28 countries after a massive earthquake measuring 8.7 on the Richter scale hit waters off the western coast of Aceh in northern Sumatra and tremors were felt in surrounding regions.

India initially issued a tsunami alert to the Andaman and Nicobar Islands (in the Indian Ocean) and coastal regions of southern states of Tamil Nadu and Andhra Pradesh after strong tremors were felt in several different cities including Chennai, Bangalore, Kolkata, Mumbai and Thiruvananthapuram. However, since then, according to an IBNLive report, the country has scaled down the threat.

"I have spoken to chief secretaries of Andhra, Orissa, Tamil Nadu and Andaman and Nicobar. Collectors in coastal districts have been asked to broadcast on radio so that fishermen at sea can come back," said the country's Home Secretary, RK Singh.

In Tamil Nadu, strong tremors were felt in the southern parts of the capital city, Chennai. People in apartment buildings rushed out of their houses and towards safer areas. According to reports, Chennai policemen used megaphones to ask people to move away from coastal areas and mobile phone networks have reportedly been jammed with concerned callers. In Andhra Pradesh, fishermen were being asked to return from the sea and in the Andaman and Nicobar Islands, civilians have been asked to move to higher ground.

Meanwhile, in the capital city, Kolkata, of the state of West Bengal, a number of people rushed out of offices in Park Street and the downtown BBD Bagh area as windows and doors rattled and some buildings developed cracks. The Metro service was suspended and passengers were asked to vacate the stations. People residing near the coast were also asked to vacate the place.

National Disaster Response Force (NDRF) teams have already been rushed to the Andaman and Nicobar Islands, as well as coastal regions of Andhra Pradesh, Tamil Nadu and Kerala.

The other countries that have been given tsunami alerts include Indonesia, Sri Lanka, Australia, Myanmar, Thailand and the Maldives, among a host of others.

Tsunami Alert in India: Possible Timings

- Tsunami likely to hit Little Andaman at 15:46 IST

- Tsunami likely to hit Port Blair at 16:02 IST

- Tsunami likely to hit North Andaman at 16:22 IST

- Tsunami likely to hit Chennai at 16:57 IST

- Tsunami likely to hit Kakinada at 17:35 IST

- Tsunami likely to hit Trivandrum at 17:38 IST

- Tsunami likely to hit Mangalore at 19:06 IST

- Tsunami likely to hit Bombay at 21:38 IST

(Information from IBNLive.in)

UPDATE

The Indian government scaled down its tsunami alert and said there was no cause for panic along India's coastline. The National Disaster Management Authority had earlier issued a tsunami warning for the Andaman and Nicobar Islands and an alert to coastal areas of southern states of Andhra Pradesh and Tamil Nadu.

"There is no specific threat. It was a watch and alert. There is no likelihood of any tsunami in the Indian Ocean region," NDMA Vice President Sashidhar Reddy has said to PTI.

"Tsunami possibility is virtually ruled out," he said, adding that the Andaman and Nicobar Islands administration and the Army stationed there had informed the NDMA that so far no waves have been noticed in the island. He also said that the earthquake that struck the Sumatra islands was not the kind of tremors that usually triggers tsunami tidal waves.

Meanwhile, the tsunami warning has also been scaled down for Indira Point and Katchal in Nicobar islands.

UPDATE

According to a report by Indian news channel NDTV, the Indian government has lifted its tsunami warning which was sent out after a massive earthquake measuring 8.6 on the Richter scale hit off the coast of Indonesia on Wednesday evening, the Press Trust of India reports. The report added that a second round of tremors was felt in India in cities like Kolkata and Chennai at 4.25 pm (local time on 11 April) but there was no tsunami threat from these aftershocks. India's Nicobar Islands, closest to the epicentre of the quake, is still on alert.

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