Wednesday, September 30, 2009

Indonesia:Padang Earthquake (September 30, 2009) Explained

Padang Earthquake (September 30, 2009) and Banda Aceh quake (December 26, 2004) Explained

Indonesia lies on the Pacific Ring of Fire. Consequently it is an area great crustal instability. Today's earthquake of magnitude 7.6 struck at sea at 10:16 UTC at a depth of 87 kilometres (54 miles), 53 kilometres northwest of Padang city in West Sumatra province, the United States Geological Survey reported. This was followed by another quake of magnitude 5.5 at 10:38 UTC.
The great Indo-Australian Plate (Indian Plate) underlies the Indian Ocean and Bay of Bengal and is drifting north-east at an average of 6 cm/year (2 inches per year). The Indo-Australian Plate (Indian Plate) subducts the Burma Plate (Eurasian Plate) at the Sunda Trench. Padang city lies close to this subduction zone. A megathrust fault is the boundary between a subducting and an overriding plate. A megathrust earthquake is produced by a sudden slip along this fault.

The town of Padang has been devastated. At the time of writing 75 people are reported dead with thousands of people trapped under collapsed buildings.

The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred with an epicentre off the west coast of Sumatra (off Banda Aceh). The 9.15 magnitude quake, had its epicentre roughly 600km northwest of Padang.
c 1,600 km (994 mi) of faultline slipped (or ruptured) about 15 m (50 ft) along the subduction zone where the India Plate slides (or subducts) under the overriding Burma Plate (Eurasian Plate). The earthquake triggered a series of devastating tsunami along the coasts of most landmasses bordering the Indian Ocean, killing nearly 230,000 people in eleven countries, and inundating coastal communities with waves up to 30 meters (100 feet) high. Coastal locations in Indonesia, Sri Lanka, India, and Thailand suffered most.

1 comment:

Wild Gypsy said...

Even though we are out in the woods, we knew there must have been a large quake sometime last night in South Pacific because they issued a tsunami advisory. According to the local newspaper, on-lookers were hoping to see a larger wave which is really-really-really dumb thinking if you ask me.

--- My sympathies to all who were truly affected by this disaster!