Seismicity of the Hindu Kush Region: Deep-Focus Earthquakes and the 2002 Jurm Event

The Hindu Kush region of northeastern Afghanistan occupies a complex tectonic setting at the western termination of the Himalayan collision zone. Here, the Indian plate converges with the Eurasian plate, producing a steeply dipping seismic zone that extends to depths exceeding 200 km. This geometry results from the northward subduction of remnants of the Tethyan oceanic lithosphere, generating frequent intermediate- and deep-focus earthquakes rather than typical shallow crustal events. On 3 March 2002 at 12:08 UTC, a magnitude 7.4 earthquake struck 51 km southwest of Jurm, Afghanistan, at a focal depth of 225.6 km. The event originated within the subducting slab, where brittle failure occurs despite the high confining pressures at such depths. Its location and depth align with the well-documented seismogenic volume beneath the Hindu Kush, a zone characterized by intense seismic activity extending from approximately 100 km to more than 250 km depth. Since 1 January 2000, several other large earthquakes have occurred in close proximity. Two magnitude 7.5 events struck the Hindu Kush region on 26 October 2015, located 10 km and 38 km from the 2002 epicenter, respectively. These events further illustrate the persistent deep seismicity of the area and the potential for multiple large ruptures within a short time frame along the same slab segment. The geological history of the region reflects ongoing continental collision that began in the Eocene and continues today at rates of roughly 4–5 cm per year. This convergence has thickened the crust and driven the descent of lithospheric material, sustaining the deep earthquake source zone for millions of years. Paleoseismic and geodetic studies indicate that the Hindu Kush slab is progressively detaching, a process that may influence future seismic patterns. Although the great focal depths of these earthquakes limit surface damage compared with shallow events, strong shaking can still affect populated valleys, and secondary hazards such as landslides remain possible on steep terrain. Continued seismic monitoring is essential for refining hazard assessments in this tectonically active segment of Afghanistan.

References

USGS Earthquake Catalog (events 2002–2015) Geological Survey of Afghanistan tectonic summaries