JAKARTA, Sep 13 (Reuters) Rescue teams and troops headed today for Indonesia's Sumatra coast as aftershocks continued to pound a region where a powerful earthquake the night before killed six people and perhaps many more.
Japan's Meteorological Agency issued a tsunami warning for Indian Ocean countries after the latest aftershock, a shallow quake which the U.S. Geological Survey (USGS) said measured 7.5.
''The city is in complete chaos. Everyone is heading to higher ground, I saw one house collapsed to the ground. I'm trying to save my family,'' said a Reuters witness in Padang, the capital of West Sumatra, soon after the first quake.
Indonesia's Health Ministry crisis centre in Jakarta said the latest casualty figures showed that six people had been killed and 40 injured after the initial 8.4 magnitude quake, which was also felt in neighbouring Singapore, Thailand and Malaysia.
But David Oppenheimer, a scientist with the USGS in California, said the death toll could well rise as authorities take stock of the impact in the light of day.
A quake with an eight magnitude typically leads to partial collapse of buildings, houses moved off their foundations, and other damage, he said.
''That's the kind of stuff that causes death, especially in the Third World. I think there is an information blackout at this point.'' Japan's Meteorological Agency warned of a tsunami risk for Australia's Coco Islands and, further afield, the coasts of India's Andaman and Nicobar Islands and Sri Lanka within 3 hours.
A huge earthquake measuring more than 9 struck the same area of Indonesia on December 26, 2004, causing a massive tsunami and over 230,000 deaths in countries across the region.
Indonesia suffers frequent quakes, as it lies on an active seismic belt on part of the so-called Pacific ''Ring of Fire''.
Many people chose to sleep out in the open on Wednesday night rather than return indoors, a Red Cross official in Bengkulu, close to the epicentre of the quake, told Reuters.
''The emergency rescue system has mobilised and the president has ordered the military to help the rescue effort,'' President Susilo Bambang Yudhoyono's spokesman said.
Rustam Pakaya, head of the health ministry crisis centre, said the government would send one tonne of medicine, three tonnes of food supplements, and one tonne of noodles on Thursday for displaced people in the area.
Reuters SZ VP0746