7/17/2006 Java Tsunami

Updated 7/18/2006

A Magnitude 7.7 earthquake, which occurred at 08:19 GMT, 15:19 local time July 17, 2006, under the ocean South of the Indonesian island of Java triggered a tsunami that hit the south Java coast barely an hour later. The epicenter of the quake was 225 miles south of Jakarta and 225 miles SW of Yogyakarta, which was hit by a earthquake on May 26 that killed more than 5800 people. This earthquake itself caused only light to moderate shaking throughout Java, however tsunami waves over 2 meters high arriving without warning most places claimed 341 lives with 250 people still missing and 42,000 displaced. Eyewitnesses reported a black wall of water that swept inland smashing boats, houses, businesses and coastside resorts.

The Indonesian government said that many people fled inland when they felt the earthquake, which is what experts advise, but many did not realize the danger of tsunami and even followed receding water out onto the seabed only to be caught when the waves came in. The water came as far as half a kilometer inland. Initial reports indicated heavy damage in the resort of Pangandaran, although likely much of the coast was affected to some degree.

According to the USGS, "The earthquake occurred as a result of thrust-faulting on the boundary between the Australian Plate and the Sunda Plate. On this part of their mutual boundary, Australian Plate moves NNE with respect to the Sunda Plate at about 59 mm/year. The Australian Plate thrusts beneath the Sunda Plate at the Java Trench, South of Java, and is subducted to progressively greater depths beneath Java and North of Java. The earthquake occurred on the shallow part of the plate boundary about 50 Km north of the Java Trench. ... This year's May 26 devastating Yogyakarta earthquake, Magnitude 6.3, occured at shallow depth within the overriding Sunda Plate."

(See the Plate Tectonics page for more information on these processes.) The US Geological Survey (USGS) is an invaluable resource in understanding and tracking earthquakes.

US Geological Survey page on this quake

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