Earthquakes Beneath the Himalayas and Tibet: Evidence for Strong Lithospheric Mantle

Abstract

Eleven intracontinental earthquakes, with magnitudes ranging from 4.9 to 6, occurred in the mantle beneath the western Himalayan syntaxis, the western Kunlun Mountains, and southern Tibet (near Xigaze) between 1963 and 1999. High-resolution seismic waveforms show that some focal depths exceeded 100 kilometers, indicating that these earthquakes occurred in the mantle portion of the lithosphere, even though the crust has been thickened there. The occurrence of earthquakes in the mantle beneath continental regions where the subduction of oceanic lithosphere ceased tens of millions years ago indicates that the mantle lithosphere is sufficiently strong to accumulate elastic strain.