Seismic hazard assessment of Afghanistan

Afghanistan is located at the collision boundary of the Indian, Eurasian and Arabian plates and, therefore, lies in a seismically active region. Few probabilistic seismic hazard analysis (PSHA) studies have been carried out for Afghanistan, which present only peak ground acceleration (PGA) values. This study presents PGA and spectral acceleration (SA) values for 0.2 and 1.0s for return periods of 475, 975 and 2475years. The study adopts the Cornell (Bull Seismol Soc Am 58(5):1583-1606, 1968), McGuire (1976) approach for the PSHA and is based on an updated and homogenized earthquake catalogue consisting of 29,097 events greater than magnitude 4.0. Two declustering models, two seismic source models and four ground-motion prediction equations for shallow and deep earthquakes are used in this study. The PSHA results are combined using a logic tree approach with a total of 16 branches. The PGA and SA values for the different provinces of Afghanistan are obtained. The results are also shown as contour maps. The PGA values range from 0.06 to 0.66g, 0.09 to 0.82g and 0.13 to 1.10g for return periods of 475, 975 and 2475years, respectively. The PSHA yields higher PGA values for the Badakhshan, Kunduz Takhar and Kabul provinces, which lie in the northeastern part of country where active sources of the Hindukush and Pamir ranges are located. The hazard values obtained in this study are observed to be generally consistent with the study of Zhang et al. (Ann Geofis 42(6):1167-1190, 1999). In addition, a comparison of the current study with the hazard maps of the bordering countries generally shows consistent results.