The fault that ruptured in 2004 was able to move much more of the seafloor than the quake that followed it.
Credit: Nicolle Rager Fuller/NSF.
Editor's Note: As of 1 p.m. ET, the tsunami watch has been canceled, according to the National Weather Service.
An earthquake of magnitude 8.6 struck off the Indonesian island of Sumatra Wednesday, sending residents scrambling to higher ground as an Indian Ocean-wide tsunami watch was issued.
The earthquake struck at 02:38 p.m. local time (08:38:37 UTC), with its epicenter 269 miles (434 km) southwest of Banda Aceh, Sumatra, Indonesia, and 1,116 miles (1,797 km) west-northwest of Jakarta, Java. Reports suggest the quake occurred nearby the 9.1-magnitude 9.1-magnitude undersea earthquake that rumbled near Sumatra on Dec. 6, 2004, and stretched 750 miles (1,200 km) to the north. The resulting tsunami devastated coastlines along the Indian Ocean, with tsunami waves up to 100 feet (30 meters) high. More than 230,000 people died and millions were left homeless.
So far, the National Weather Service's Pacific Tsunami Warning Center has issued a tsunami watch, which means that there is a risk for a tsunami, but the existence of a wave has not yet been verified. A tsunami warning, on the other hand, means a tsunami has been verified and could be close. Under a tsunami warning, the National Weather Service will give estimated times of wave arrival for coastal areas.
According to the Jakarta Post, National Disaster Mitigation Agency (BNPB) spokesman Sutopo Purwo Nugroho confirmed that several aftershocks could potentially trigger a tsunami. As such, "residents of several cities in Sumatra hurriedly ran for their lives," according to the Post article.