Magnitude 7.6 - SOUTHERN SUMATRA, INDONESIA
2009 September 30 10:16:09 UTC
|Depth||81 km (50.3 miles) set by location program|
|Region||SOUTHERN SUMATRA, INDONESIA|
|Distances||60 km (35 miles) WNW of Padang, Sumatra, Indonesia|
225 km (140 miles) SW of Pekanbaru, Sumatra, Indonesia
475 km (295 miles) SSW of KUALA LUMPUR, Malaysia
975 km (600 miles) NW of JAKARTA, Java, Indonesia
|Location Uncertainty||horizontal +/- 4.2 km (2.6 miles); depth fixed by location program|
|Parameters||NST=405, Nph=405, Dmin=534.3 km, Rmss=0.92 sec, Gp= 18°,|
M-type=teleseismic moment magnitude (Mw), Version=A
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At least 1100 people were killed, 2181 were injured and thousands are still unaccounted for in the Padang area. More than 2650 buildings have been damaged in the area and landslides have disrupted power and communications. Felt (VII) at Padang. Widely felt throughout Sumatra and Java, Indonesia, Malaysia, Singapore and Thailand. A small local tsunami with wave heights of 27 centimeters (amplitude measured relative to normal sea level) was generated.
The southern Sumatra earthquake of September 30, 2009 occurred as a result of oblique-thrust faulting near the subduction interface plate boundary between the Australian and Sunda plates. At the location of this earthquake, the Australian Plate moves north-northeast with respect to the Sunda plate at a velocity of approximately 60 mm/yr. On the basis of the currently available fault mechanism information and earthquake depth of 80 km, it is likely that this earthquake occurred within the subducting Australian Plate rather than on the plate interface itself. The recent earthquake was deeper than typical subduction thrust earthquakes that generally occur at depths less than 50 km. The subduction zone surrounding the immediate region of this event has not witnessed a megathrust earthquake in the recent past, rupturing last in an earthquake of M 8.5 or larger in 1797. Approximately 350 km to the south, a 250 km section of the plate boundary slipped during an Mw 8.4 earthquake in September 2007, while approximately 300 km to the north, a 350 km section slipped during the Mw 8.7 earthquake of March 2005. In early 2008, the plate boundary updip of todays earthquake was active in a sequence of Mw 5-6 earthquakes. It is not clear how todays earthquake is related to the sequence of megathrust subduction zone events on the shallower section of the plate boundary.
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Scientific & Technical Information
- USGS Centroid Moment Tensor Solution
- Global CMT Project Moment Tensor Solution
- USGS Body-Wave Moment Tensor Solution
- USGS WPhase Moment Tensor Solution
- Historic Moment Tensor Solutions
- Finite Fault Model
- Phase Data
- Seismicity Cross Section
- Theoretical P-Wave Travel Times
- Energy and Broadband Solution
- Subduction Zone Geometry Analysis
Additional Information, News Reports
- Preliminary Earthquake Report
- U.S. Geological Survey, National Earthquake Information Center:
World Data Center for Seismology, Denver