The 2001 M7.5 Earthquake East of Kendari, Indonesia: Tectonic Context and Regional Seismicity

The M7.5 earthquake that struck 155 km east of Kendari, Indonesia, on 19 October 2001 at 03:28 local time originated at a focal depth of 33 km. This event stands as a significant example of the seismic hazards inherent to Sulawesi’s complex tectonic setting. The quake occurred within a zone of active convergence involving the Australian, Sunda, and Philippine Sea plates, where oblique subduction and strike-slip faulting generate frequent moderate-to-large earthquakes. Sulawesi occupies a pivotal position at the triple junction of these major plates. The region’s geology features a collage of island arcs, ophiolite complexes, and sedimentary basins shaped by millions of years of plate interaction. The 2001 event’s intermediate depth and magnitude reflect rupture along a thrust or reverse fault segment within the subduction interface or an associated splay fault. Such mechanisms are typical for the area, where the Australian plate’s northward motion is accommodated partly by subduction beneath the Sunda plate and partly by lateral escape along major strike-slip systems such as the Palu-Koro and Matano faults. Historically, Sulawesi has experienced recurrent strong shaking. Instrumental records since 2000 document several M7+ events across the island, underscoring persistent strain accumulation. The 19 October 2001 earthquake fits this pattern, releasing energy at a depth that limited surface rupture but still produced widespread felt intensities across southeastern Sulawesi. Post-event studies confirmed aftershock sequences aligned with the regional stress field, consistent with ongoing plate-boundary deformation. Updated assessments of seismic hazard in the Kendari region incorporate both historical catalogs and geodetic measurements from GPS networks. These data reveal convergence rates of several centimeters per year, implying continued potential for future large events. Although the 2001 quake did not generate a destructive tsunami, its occurrence highlights the need for robust building codes and early-warning systems in a region underlain by variable soil conditions that can amplify ground motion. In summary, the 2001 M7.5 earthquake exemplifies the dynamic tectonic environment east of Kendari. Continued monitoring and integration of geological, geodetic, and paleoseismic data remain essential for refining hazard models and mitigating risk in this rapidly deforming part of Indonesia.

References

USGS Earthquake Catalog (event parameters for 19 Oct 2001). Global CMT Project (focal mechanism and depth constraints). Tectonic framework derived from regional plate-motion studies published in peer-reviewed journals.