Evolution and characteristics of deep seismicity beneath the Himalayas

Abstract:

The Himalayan orogen, formed by the continental collision between the Indian and Eurasian plates, is one of the most tectonically active regions in the world. A large number of geophysical data and previous studies have shed light on the mountain-building processes and lithospheric structure of the orogen. The temporal and spatial characteristics of the deep seismicity, however, is somewhat limited. Thus, compiling an extended catalog for the Himalayan deep earthquakes is of great importance.

To create this catalog, we collected all the available continuous seismic data that operated during the last two decades in the Himalayas region (networks mostly operated between the following periods; 2001-2005 and 2013-2016). We started with the earthquake origin times of all the available deep earthquakes (i.e., hypocentral depths >50 km) from data centers and previous studies. We applied a systematic processing routine (e.g., picking P- and S-wave phases), and we obtained absolute earthquake locations using a 1-D velocity model. We have calculated around 700 preliminary earthquake locations based on high-quality picks. We intend to refine these preliminary locations and calculate local magnitudes.

Using this catalog, we seek to examine the temporal evolution and properties of the Himalayan deep seismicity. This information may help provide a better understanding of the local processes and mechanisms controlling seismogenesis at depth and highlight characteristics of the orogen.