The following is a release by the United States Geological Survey, National
Earthquake Information Center: An earthquake occurred 130 km (80 miles) SW of
Bengkulu, Sumatra, Indonesia and 625 km (390 miles) WNW of JAKARTA, Java,
Indonesia at 5:10 AM MDT, Sep 12, 2007 (6:10 PM local time in Indonesia). The
magnitude and location may be revised when additional data and further analysis
results are available. Earthquakes of this type sometimes cause tsunamis,
however the USGS has no information that an actual tsunami has been generated.
For information about tsunamis, contact the NOAA Tsunami Warning Centers at
http://tsunami.gov.
Felt Reports
At least 25 people killed, 161 injured, 52,522 buildings damaged or destroyed
and roads damaged in Bengkulu and Sumatera Barat. A tsunami with a wave height
of 90 cm was measured at Padang. Power and telephone outages occurred. Felt by
people in high-rise buildings at Jakarta and in Malaysia, Singapore and
Thailand.
Tectonic Summary
The magnitude 8.4 and 7.8 southern Sumatra earthquakes of September 12, 2007
occurred as the result of thrust faulting on the boundary between the Australia
and Sunda plates. At the location of these earthquakes, the Australia plate
moves northeast with respect to the Sunda plate at a velocity of about 60
mm/year. The direction of relative plate motion is oblique to the orientation of
the plate boundary offshore of the west coast of Sumatra. The component of
plate-motion perpendicular to the boundary is accommodated by thrust faulting on
the offshore plate-boundary. Much of the component of plate motion parallel to
the plate boundary is accommodated by strike-skip faulting on the Sumatra fault,
which is inland on Sumatra proper.
The magnitude 8.4 earthquake of September 12, 2007 is the fourth earthquake
of magnitude greater than 7.9 to have occurred in the past decade on or near the
plate boundaries offshore of western Sumatra. This earthquake occurred just
north of the source region of the magnitude 7.9 earthquake on June 4, 2000. The
September 12, 2007 magnitude 7.8 earthquake occurred about 225 km northwest of
the magnitude 8.4 earthquake at the northern end of the aftershock zone. These
two earthquakes and their aftershocks overlay the southern portion of the
estimated 1833 rupture zone, which extends from approximately Eggano Island to
the northern portion of Siberut Island. The great magnitude 9.1 earthquake of
December 26, 2004, which produced the devastating Indian Ocean tsunami of that
date, ruptured much of the boundary separating the India plate and the Burma
plate. Immediately to the south of the great 2004 earthquake, the magnitude 8.6
Nias Island earthquake of March 28, 2005, ruptured a segment of the plate
boundary separating the Australia and Sunda plates. Since the December 26, 2004
earthquake, much of the Sunda trench between the northern Andaman Islands to
Eggano Island, a distance of more than 2,000 km, has ruptured in a series of
large subduction zone earthquakes.
Tectonic
Summary PDF
Modern
Ruptures PDF
Earthquake
Information for Asia
Earthquake
Information for Indonesia
Tsunami Information
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Historic Moment Tensor Solutions
