(Updates number of injured, houses damaged) JAKARTA, Dec 18 (Reuters) - Three moderate earthquakes struck Indonesia's Sumatra island on Monday, killing four people in one area and triggering landslides, officials said. The first earthquake struck at 4:10 a.m. (2110 GMT Sunday) with a magnitude of 5.8. Its epicentre was 128 km (80 miles) under the sea southwest of the city of Banda Aceh, an official from Indonesia's meteorology and geophysical agency said. The second, which had a magnitude of 5.7, came about 30 minutes later on land at a depth of 53 km in an area northwest of the city of Padang, the official said. A third quake, of 5.5 magnitude, hit at 8:24 a.m. in North Sumatra, the official said. The U.S. Geological Survey on its Web site (http://www.usgs.gov) gave much shallower depths for the first two quakes. Eddy Sofyan, a spokesman for the administration in North Sumatra province, said the quake killed four people -- a child, a teenager and two elderly men -- as well as injuring 41 others and damaging about 135 houses in the town of Muarasipongi. Three of the victims died when their house collapsed while the other had a heart attack, a local policeman, Aminuddin Arif, said. Another local official told Elshinta radio that 250 houses were destroyed in Muarasipongi, which is 1,100 km (680 miles) northwest of the capital Jakarta. About 1,000 residents displaced by the quake had taken shelter in tents erected in open fields in the town. Workers had managed to clear the town's main road blocked by landslides triggered by the quake, allowing relief supplies to reach the stricken villagers, Sofyan said. "We are sending medical teams, 30 tents and a search-and-rescue team to the location," he said. As well as the three moderate quakes, 26 smaller aftershocks occurred, said a meteorology official in the city of Padang in West Sumatra province. Officials said there was no risk of a tsunami after the earthquakes, which were felt in Singapore, just across the Strait of Malacca on the other side of Sumatra. Earthquakes are frequent in Indonesia, which straddles part of the so-called "Ring of Fire" in the Pacific. A huge quake of magnitude 9.1 in December 2004 just off Sumatra's northwest coast caused a tsunami that crossed the Indian Ocean to Sri Lanka, Thailand and even to eastern Africa. More than 230,000 people died or went missing in a dozen countries in the devastation.
