3D attenuation tomography of the Uttarakhand, NW Himalaya: Linkage to fluid or partial melt zones - Seismic hazard

This work proposes the shear-wave attenuation tomography of the Garhwal and Kumaun regions, Uttarakhand Himalaya, to investigate the crustal state. Based on attenuation characteristics, the high attenuated layer identified starts at ∼10 km in the Garhwal region and ∼5 km in the Kumaun region. The obtained model revealed that quality factor (Q) values vary from 16 to 664 and 49 to 866 at 1 Hz frequency for the Kumaun and Garhwal regions, respectively. The high attenuation rate (1/Q) in the Kumaun region compared to the Garhwal region may be due to the high attenuated layer at a shallower depth in the Kumaun region. The comparatively low attenuation rate of the Garhwal characterizes it as a region with high seismic hazard potential. Pioneeringly, layered frequency-dependent attenuation models are proposed up to a depth of 30 km for six different layers with 5 km thickness each, which will provide new insight into seismic hazard evaluation.