M 7.5 - 63 km NW of Maubara, Timor Leste
- 2004-11-11 21:26:41 (UTC)
- 8.152°S 124.868°E
- 10.0 km depth
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- Magnitude
- 7.5 mwc
- Depth
- 10.0 km
- Time
- 2004-11-11 21:26:41 UTC
Moment Tensor Fault Plane Solution Finite Fault Cross-section of slip distribution. View Nearby Seismicity - Time Range
± Three Weeks - Search Radius
250.0 km - Magnitude Range
≥ 4.0
Contributors US
USGS National Earthquake Information Center, PDE
Tectonic Summary
The November 11, 2004, M 7.5 earthquake near Kepulauan Alor, Indonesia, occurred as the result of shallow thrust faulting on or near the convergent boundary between the Banda Sea microplate to the north and the Timor microplate to the south. Focal mechanism solutions indicate that rupture occurred on either a steep, near-vertical reverse fault or on a shallow, southward-dipping thrust fault. Of these two possible fault orientations, finite-fault modeling of globally recorded seismic data is more consistent with slip on the southward-dipping thrust fault. At the location of the earthquake, the Banda Sea microplate thrusts beneath the Timor microplate to the south at a velocity of about 30 mm/yr. The two microplates are sandwiched along with other microplates between the larger Sunda, Philippine Sea, Australia, and Pacific plates. The location, depth, and focal mechanism solutions of the November 11th earthquake are consistent with it having occurred on the thrust interface between these two local microplates. A similar earthquake occurred only 20 km to the west in July 1991, a M 6.9 earthquake that resulted in 23 fatalities and 181 injuries.
While commonly plotted as points on maps, earthquakes of this size are more appropriately described as slip over a larger fault area. Thrust-faulting events of the size of the November 11, 2004, earthquake are typically about 80x40 km (length x width); modeling of this earthquake implies dimensions of about 70x50 km, predominantly up-dip and east of the hypocenter.
Hayes et al. (2016) Tectonic summaries of magnitude 7 and greater earthquakes from 2000 to 2015, USGS Open-File Report 2016-1192. (5.2 MB PDF)
Summary Poster