Location:

Period:

11 Nov 2004 21:26:41 - 13 Nov 2004 08:52:20 (1 day 11 hours 25 minutes)

Volcanoes in 100km radius:

Sirung(82km)

Earthquakes:

M 7.0+:

M 7.5; 63 km NW of Maubara, Timor Leste; (11 Nov 2004) (7km from the swarm center)

2 swarms found nearby.

2008

PS20080419.1(109.0km)

19 Apr

1 day 9 hours

8 earthquakes

2015

PS20151104.1(41.1km)

3 Nov

11 hours

5 earthquakes

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Seismic Swarm PS20041111.1: Analysis of the November 2004 Event Near Timor Leste

A seismic swarm designated PS20041111.1 occurred in the waters north of Timor Leste, centered approximately 79 km north of Maubara. The sequence began at 21:26 UTC on 11 November 2004 and concluded at 08:52 UTC on 13 November 2004, spanning 35 hours and 25 minutes. During this period, 17 earthquakes were recorded, with the largest event registering magnitude 7.5 at a focal depth of 10 km. The swarm initiated with the magnitude 7.5 mainshock at 21:26:41 UTC on 11 November, located 7 km from the swarm centroid. This was followed within minutes by a magnitude 5.5 event at 21:36:49 UTC, also at 10 km depth. Subsequent activity included additional magnitude 5.5 and 6.4 events later that evening, with magnitudes ranging from 5.0 to 6.4 and depths predominantly at 10 km. The sequence tapered with smaller events on 12 and 13 November, including a magnitude 5.3 shock at 11 km depth on the final day. Geologically, the region lies within the Banda Arc collision zone, where the Australian continental margin converges with the Eurasian plate. This tectonic setting produces shallow crustal earthquakes and occasional deeper events along the subduction interface. Timor Leste experiences elevated seismicity due to ongoing oblique convergence and the presence of active thrust faults. Historical records indicate recurrent moderate-to-large events, consistent with the 2004 swarm's characteristics. The 2004 sequence aligns with the area's pattern of clustered aftershock activity following a major rupture. Depths clustered near 10 km suggest rupture within the upper crust, typical for this margin. No surface rupture was reported, though the mainshock's magnitude indicates significant energy release capable of generating local ground shaking. This swarm provides insight into stress redistribution along the plate boundary, where an initial large event triggered a cascade of smaller ruptures over a compact area. Such sequences are common in convergent settings and underscore the value of continuous monitoring for hazard assessment in Timor Leste.

References

SeismoSight internal swarm classification PS20041111.1.
USGS Earthquake Catalog (events since 2000).
Regional tectonic summaries from the Australian Plate boundary studies.