A 6.9-magnitude earthquake has struck northern Sumatra, Indonesia, just hours after a 7.7-magnitude quake that killed hundreds of people, the US Geological Survey (USGS) said.
The epicenter was located in Pematangsiandar, 126 kilometers from the capital Medan in western Indonesia. The focal depth of the earthquake was 158 kilometers.
The death toll so far is 40 from the first 7.7 magnitude earthquake.
The vast Indonesian archipelago is prone to frequent seismic and volcanic activity due to its location on the Pacific Ring of Fire.
Meanwhile, a magnitude 5.8 earthquake struck off the northern coast of Papua New Guinea, the German Center for Geosciences said. Its focal depth was measured at 10 kilometers.