The 2004 Maubara Earthquake: Tectonic Setting of Timor-Leste

On 11 November 2004 at 21:26 local time, a magnitude 7.5 earthquake occurred 63 km northwest of Maubara, Timor-Leste, at a focal depth of 10 km. This shallow thrust event remains the strongest recorded in the country since 1 January 2000. Timor-Leste occupies the eastern half of Timor Island within the Outer Banda Arc, a zone of active collision between the northward-moving Australian Plate and the Eurasian Plate. Convergence occurs at roughly 7 cm per year along the Timor Trough, producing a complex system of south-vergent thrust faults and accretionary-wedge structures. The 2004 rupture is interpreted to have taken place on one of these shallow thrust planes, consistent with the observed focal depth and regional focal mechanisms. The island’s geology records a long history of subduction and eventual arc-continent collision that began in the Miocene. Timor’s core consists of Australian continental-margin sediments that were detached and uplifted during this process, while the northern coastal region lies above the actively deforming wedge. Ongoing shortening continues to generate moderate-to-large earthquakes, with the 2004 event highlighting the seismic potential of the western Timor segment. Although the earthquake produced strong shaking across western Timor-Leste and parts of Indonesian West Timor, detailed damage assessments remain limited in the published record. No significant tsunami was generated, likely because the rupture did not produce substantial vertical seafloor displacement.

References

USGS Earthquake Catalog (event page for 2004-11-11 M7.5 Timor-Leste) Global CMT Catalog (moment-tensor solution for the same event) Audley-Charles, M.G. (2011). Tectonic evolution of Timor. Geological Society of London Special Publications.