Estimation of Ground Motion Amplification for Sub-Himalayan Strata due to Hypothetical Earthquake Motions

Himachal Pradesh state is located in seismically active western Himalayas (India) and its seven districts are in seismic zone V and other in zone IV as per the seismic code of India. Ninety% area of Hamirpur district, the studied area, lies in zone V. Peak ground acceleration (PGA) is one of the most important seismic response parameters in structural seismic design, largely influenced by the sub-soil and input seismic motion characteristics. In the present work, the primary objective is to identify the areas in the district that are prone to amplification of peak ground acceleration and can be delineated for infrastructural planning. Peak ground acceleration is one of the most important parameters used in seismic design of the structures. It is estimated using the computer programme ProShake, wherein the soil parameters from 181 borehole profiles up to 30 m depth and software in-built standard earthquake input motions of magnitude 6.9, 7.0, and 7.2 used as the input parameters. The output peak ground acceleration range from 0.24 g to 0.72 g at the ground surface and from 0.21 g to 0.54 g at a depth of 10 m. There is an attenuation of peak ground acceleration at 30 m depth. The estimation of peak ground acceleration will play an important role in delineating the starta having higher peak ground acceleration amplification. This information can be effectively used for planning of important infrastructure projects like hospitals, educational institutions, and commercial establishments in an economical way in the studied area.