Over 500 Reported Dead in Sumatra Quake; AIR Analyzes Disaster

October 1, 2009

Not long after the Samoan earthquake and tsunami struck in the South Pacific, a major earthquake occurred 9500 kms (5900 miles) away off Sumatra in western Indonesia. Latest news bulletins have raised the initial death toll from the disaster to at least 500, with many more people missing and feared dead.

The US Geological Survey “issued a preliminary magnitude of 7.9 for the event, but has since downgraded this to M 7.6.,” said a bulletin from catastrophe risk modeling firm AIR Worldwide.”Depth is estimated at 80 km (49.7 miles). The tremor was felt as far away as Singapore—some 475 miles from the epicenter—and it prompted tsunami alerts for Indonesia, Malaysia, India and Thailand. These alerts have since been lifted.”

The earthquake damaged hundreds of homes and trapped thousands of people under rubble and landslides. Power failures hit Sumatra, especially around Padang, the capital of Indonesia’s West Sumatra province – the region hardest hit – making it difficult to “assess the scope of overall damage,” said AIR.

The earthquake occurred about 54 kilometers (30 miles) west northwest of Padang (population 900,000), destroying many buildings and several hotels. Two hospitals and a mall were also destroyed. In September 2007, Padang was struck by a M8.4 earthquake that killed dozens of people and collapsed several large buildings.

Dr. Bingming Shen-Tu, principal scientist at AIR Worldwide explained that the “earthquake near Sumatra occurred along the Great Sumatra Subduction Zone, where the Indo-Australia Plate subducts under Sumatra Island, which is itself part of the Sunda Plate, at a rate of 6-7 centimeters per year.

“The Indo-Australia/Sunda Plate boundary has generated some of the largest mega-thrust earthquakes in the world, including the M 9.3 mega-earthquake in December 2004—the same earthquake that spawned the 2004 Asian tsunami that killed 23,000 people— and an M 9.0 event more than a century earlier, in 1833. Today’s event occurred along the northern segment of the 1833 rupture zone. The southern segment was ruptured just two years ago, in September 2007, by two earthquakes measuring M 8.5 and M 7.9.

“Today’s earthquake event is the 4th in the last decade within a 700 km-long segment of the Great Sumatra Subduction Zone to have exceeded M 7.5. The depth and rupture mechanism of the earthquake suggest that it originated in the subducting slab (the Australia plate) instead of along the plate interface, setting it apart from typical subduction zone earthquakes.”

AIR added that according to its latest models, based on the information available, it does not expect insured losses from the earthquake to “be significant.”

Source: AIR Worldwide – www.air-worldwide.com

Was this article valuable?

Here are more articles you may enjoy.