Frequency-dependent quality factor of body waves in the Kathmandu region, Nepal

The Kathmandu region becomes situated in very close to the major thrust faults such as Main Boundary Thrust (MBT) and Main Central Thrust (MCT) has been significantly affected by a series of several major earthquakes in the past. The current study analyses the attenuation of body waves in the region using the coda normalization method based on the data of two stations (NA430 and NA060) essentially from a temporary seismic network deployed after the occurrence of the 25th April 2015 earthquake. The events considered for the study have a local magnitude of 4–5.5 ​at a depth range of 10–27 ​km. The estimated quality factor of primary and secondary waves are Q P = (44 ​± ​12.896)f (0.82 ± 0.173), Q S = (62 ​± ​19.265)f (0.94 ± 0.185) for NA430 station and Q P = (35 ​± ​9.467)f (0.93 ± 0.155), Q S = (68 ​± ​22.510)f (0.91 ± 0.198) for NA060 station. The Q S /Q P ratio more than one observed for the entire frequency range specifies the highly heterogeneous crust medium beneath the study region. The obtained quality factors could be used in the generation of target ground motion for engineering purposes and in the calculation of source parameters for seismic hazard assessment as risk reduction strategies in the study region.