Microzonation of Seismic Hazard for the State of Haryana, India

Abstract

Seismic hazard analysis has been carried out for the state of Haryana using probabilistic approach. An area with a radius of about 300 km around Haryana, between 25° to 33° N latitude and 72° to 81° E longitude, has been considered as seismic study region for the evaluation seismic hazard. The potential seismic hazard of the state is controlled by three different tectonic regimes, Himalayan frontal thrust, Aravalli-Delhi fold belt and Sargodha-Lahore-Delhi ridge. An earthquake catalogue has been developed based on the data from both historic and instrumental periods. The final catalogue has 942 events after it has been homogenized, examined to remove duplicate events, declustered and checked for completeness. The active tectonic features of the study region have been identified by superimposing epicenters of earthquakes on the tectonic map. There are 39 active tectonic features in the study region and 13 features have been identified as potential seismogenic sources. Maximum magnitude potential of the seismogenic sources has been calculated using various methods based on total fault length, sub-surface rupture length and maximum observed magnitude. Seismicity parameters have also been obtained in order to calculate return period corresponding to expected earthquake magnitude. Considering a grid size of 0.1° × 0.1°, hazard maps have been developed for expected PGA and Sa for return periods of 475 years, 2475 years and 4975 years with 10%, 2% and 1% probability of exceedance respectively in 50 years. It has been observed that the PGA values for the north and northeastern parts of the state range from 0.1g–0.35g and for rest of the areas to be ≤ 0.1g for 10% probability of exceedance in a time frame of 50 years. The PGA map developed for Haryana for the return period of 475 years has been modified for site class D using the amplification factors specified in NEHRP provisions. The PGA value ranging from 0.074g to 0.376g has been observed. The results obtained in the study have been compared with the specifications given in Indian standard code of practice.