Seismic-Hazard Assessment in the Kachchh Region of Gujarat (India) through Deterministic Modeling Using a Semi-Empirical Approach

Abstract

Online Material: Peak ground accelerations for scenario earthquakes. The Kachchh and adjoining region in western India have been affected in the past by large damaging earthquakes. In 1668, an M 7 earthquake razed Samaji, a town 200 km west of Kachchh on the Indus delta in Pakistan (Chandra, 1977). In 1819, an M w 7.6 earthquake 100 km northwest of Bhuj formed a 90 km long and 6 m high scarp along the Allah Bund fault (Bilham and Gaur, 2000). In 1845, an earthquake of modified Mercalli intensity VIII hit Lakhpat in the western part of Kutch (Rajendran and Rajendran, 2001) and an M w 6 intensity VIII earthquake struck Anjar in 1956, causing 115 deaths (Tandon, 1959; Chung and Gao, 1995). Nine damaging earthquakes of M w 5–6 have occurred during the past 155 years, on an average of every 17 years. Some of these were in the years 1864, 1903, 1940, and 1950. The last very high devastating earthquake of M w 7.6 occurred in 2001, causing 14,000 deaths and an economic loss of $10 billion U.S. (Rastogi, 2004). The major international trade traffic in oil/and gas (energy sector), bulk chemicals, and construction materials is through Gujarat coast because of its superior infrastructure in involving harbors, ports, jetties, and oil and gas pipelines. There are 42 ports, numerous jetties, several refineries, and a large number of chemical industries. Gujarat coast also lies in the most severe seismic zone (zone V) of India. In case of a major seismic event, large‐scale damage to these facilities will severely disrupt the trade traffic and adversely affect the national economy. Apart from the coastal development, Gujarat state is expanding its industrial development in other parts of Kachchh. Therefore seismic‐hazard assessment of the region is important and essentially required. The earthquake scenarios describe the effect of …