AP

Jakarta, Sep 12: A powerful earthquake hit Indonesia on Wednesday September 12, causing buildings to sway strongly in the capital, and authorities issued a tsunami warning for much of the Indian Ocean region.

The U.S. Geological Survey said the quake had a preliminary magnitude of 7.9 and hit at about 6:10 p.m. (7:10 a.m. EDT). It was centered 9.7 miles underground in the southern Sumatra area, the USGS said.

The Pacific Tsunami Warning Center issued a tsunami warning for wide areas of the region.

"Earthquakes of this size have the potential to generate a widespread destructive tsunami that can affect coastlines across the entire Indian Ocean Basin," it said.

In Jakarta, tall buildings swayed for several minutes, and occupants rushed down the stairs to escape.

Indonesia, the world's largest archipelago, is prone to seismic upheaval due to its location on the so-called Pacific "Ring of Fire," an arc of volcanos and fault lines encircling the Pacific Basin.

In December 2004, a massive earthquake struck off Sumatra island and triggered a tsunami that killed more than 230,000 people in a dozen countries, including 160,000 people in Indonesia's westernmost province of Aceh.