CNN) -- A massive earthquake struck off the coast of the Indonesian island of Sumatra on Wednesday, triggering a tsunami watch for the Indian Ocean.

The quake, which struck about 500 kilometers from Indonesia's Aceh province, had a magnitude of 8.7, the U.S. Geological Survey said. It took place at a depth of 33 kilometers.

The Pacific Tsunami Warning Center said it had issued a tsunami watch for the entire Indian Ocean.

Banda Aceh was devastated by a tsunami resulting from an earthquake in December 2004.