Indonesia lifted a tsunami alert Tuesday following a magnitude 7.1 undersea earthquake that hit off Mentawai Island, triggering panic in a region prone to fatal quakes but apparently causing no major damage or casualties.
The magnitude 7.1 earthquake was centered 170.4 kilometres southeast of Teluk Dalam, a coastal town in the South Nias Regency, North Sumatra province, at a depth of 15 kilometers (9.3 miles) under the sea, the US Geological Survey said.
The earthquake was followed by at least 5 aftershocks measuring magnitude between 5.8 and 4.6, it said. After an initial tsunami alert, Indonesia's Meteorology, Climatology and Geophysical Agency lifted the warning hours after the quake.
The agency initially put a preliminary magnitude at 7.3, but later revised it to 6.9. Variations in early measurements are common. The agency's head of the Earthquake and Tsunami Center, Daryono, who goes by a single name, said that based on sea-level observations, minor tsunamis of 11 centimeters (4.3 inches) were detected in Tanah Bala coastal area of South Nias regency.
Residents in parts of West Sumatra province, including the provincial capital of Padang, felt the earthquake strongly for about 30 seconds, causing panic, National Disaster Mitigation Agency spokesperson Abdul Muhari said. Some places ordered evacuations to higher ground.
Indonesia, a vast archipelago of 270 million people, is frequently struck by earthquakes, volcanic eruptions and tsunamis because of its location on the “Ring of Fire,” an arc of volcanoes and fault lines that arcs the Pacific.
The last major earthquake was in November last year, when a magnitude 5.6 killed at least 340 people and more than 7,700 were injured while more than 62,600 homes were damaged across 16 districts in West Java's Cianjur regency and the surrounding region. In 2004, an extremely powerful Indian Ocean quake set off a tsunami that killed more than 230,000 people in a dozen countries, most of them in Indonesia's Aceh province.
