The quake struck off Indonesia’s Sumatra island, U.S. and Indonesian monitors reported, prompting an Indian Ocean-wide tsunami alert.

The tremors were felt far and wide in southern and eastern parts of India, Sri Lanka, Australia, Thailand, Singapore and Malaysia. The quake’s magnitude was 8.7 on Richter scale and it struck 431-km off the Indonesian city of Banda Aceh.

In India, tremors were felt in Tamil Nadu, Kerala, Karnataka, Andaman and Nicobar islands, Assam and West Bengal.

Banda Aceh in Indonesia was near the epicentre of a devastating 9.1-magnitude quake in 2004 that triggered a tsunami across the Indian Ocean, which killed 220,000 people, including 170,000 in Aceh.

Residents in Banda Aceh reported the ground shaking violently. The ground shook for nearly five minutes with telephone connections going down briefly. Terrified people left their dwellings and ran for cover.

People were trying to leave affected area, with whatever modes of transport available. Traffic jams were seen everywhere.