The Indian Met Department on Monday night did not rule out the possibility of a tsunami striking the country's coastal areas after a massive earthquake, measuring 8.7 on the Richter scale, hit off the coast of the Sumatra island in Indonesia, Union Science and Technology Minister Kapil Sibal said.

However, the United States' National Oceanic and Atmospheric Administration's website said authorities can assume the danger has passed if no tsunami waves are observed in the region near the epicentre within three hours of the earthquake.