3D Absorption and 2D Scattering Attenuation of the Kashmir “seismic Gap” in NW Himalaya

Abstract The Kashmir “seismic gap” in NW Himalaya has accumulated sufficient elastic strain to cause a great earthquake. Constraining the lateral and depth‐dependent variations in seismic attenuation across this region is essential for ground‐shaking estimation from earthquakes. Recently acquired waveform data from precisely‐located‐local earthquakes are used to compute: (a) 3D S‐wave attenuation using coda‐normalization; (b) 3D intrinsic absorption using coda quality‐factor; and (c) 2D scattering from peak delay‐time measurements. Our results, interpreted in light of the structure and seismicity, reveal frequency‐dependent variations in attenuation, controlled by the crustal structure, lithology, geometry of major thrusts and active faults. High attenuation/absorption characterize the sedimentary/meta‐sedimentary rocks of the Sub‐Himalaya and the Lesser Himalayan Duplex in the Kishtwar Window (KW). Enhanced attenuation and scattering within the KW and its surroundings are attributed to concentrated seismicity associated with the frontal ramp of the Main Himalayan Thrust (MHT). In contrast, the reentrants of the Main Frontal Thrust and Reasi Thrust, representing surface expressions of MHT lateral‐ramp, exhibit relatively low attenuation/absorption. This is possibly due to shallowing of the underthrust Indian crust across the lateral ramp. The Higher Himalayan crystallines show low attenuation and weak scattering. The Kashmir Valley shows lateral contrasts in attenuation/absorption, indicating varying sedimentary thicknesses. The MHT demarcates the contrast between the high absorption/attenuation Himalayan Wedge above and the low absorption/attenuation underthrusting Indian crust below. The Indian upper‐crust shows high attenuation in patches, possibly related to fluids from metamorphic dehydration reactions or inherited heterogeneity.