Epicenter of earthquake off the coast of northern Sumatra.
A massive earthquake struck off the coast of the Indonesian island of Sumatra on Wednesday afternoon, triggering a tsunami watch for the Indian Ocean, which was later canceled.
The quake struck about 434 kilometers (270 miles) southwest of Banda Aceh, the capital of Indonesia's Aceh province, and had a magnitude of 8.6, the U.S. Geological Survey said. It took place at a depth of 23 kilometers (14 miles).
A second large quake, with a magnitude of 8.2, occurred off the west coast of Sumatra about two hours later, the USGS said.
Gary Gibson from the Seismology Research Center in Melbourne, Australia, said the location of the second quake reduced the possibility of a tsunami.
There was also a series of smaller quakes off the west coast of northern Sumatra with magnitudes between 5.1 and 5.4.
There were no reports of destruction or deaths.
Indonesian President Susilo Bambang Yudhoyono said on local television that there were no reports of casualties or damage in Aceh.
Four people were slightly injured on Simeulue Island, off the coast of Aceh, the National Disaster Management Agency said Wednesday.
The Pacific Tsunami Warning Center issued a tsunami watch for the entire Indian Ocean. And a few hours later, the center announced the tsunami watch was canceled.
"A significant tsunami was generated by this earthquake. However, sea level readings now indicate that the threat has diminished or is over for most areas," the center said.
