Seismotectonics of the Kangra region, Northwest Himalaya

The occurrence of major and moderate earthquakes having thrust and strike-slip mechanisms along the longitudinal and transverse feature within the same seismogenic zone requires a detailed study of the area in order to infer the seismotectonics. The epicentral distribution of earthquakes > 4.0 (mb) between the Chamba and Sundernagar region shows the high rate of activity either north of Chamba, i.e., north of the Main Central Thrust (MCT) or north of Dharamsala in between the Panjal Thrust (PT) and MCT in the Dhauladhar Range. It is, however, surprising that all the moderate earthquakes that have been triggered in the Kangra region have either been in the frontal belt along the transverse features or have followed the arcuate belt close to the Main Boundary Thrust (MBT). The spatio-temporal variation of the seismicity from 1973 to 2000 ( > 4.0 mb) reveals a migration trend between Chamba and Sundernagar. During the seventies and early eighties, the seismicity was concentrated in the Chamba region and in the late eighties and early nineties, the seismicity shifted around Dharamsala and later further north. Additional results are discussed.