11 Int. j. econ. environ. geol. Vol:6(2) 11-16, 2015 Available online at www.econ-environ-geol.org GIS Based Study on Seismicity of Makran over 100 Years Mubarik Ali and Muhammad Jahangir Khan * Department of Earth & Environmental Sciences, Bahria University, Karachi, Pakistan *Email: jahangir.khan99@gmail.com Abstract.The earthquakes in Makran have a history of 600 years (1483-2015). The new ventures of development, urbanization, mining, and exploration for hydrocarbons in Makran region demand recent studies on seismicity. The major tectonic earthquakes are although infrequent in Makran, but are responsible for generating tsunami in coastal areas of Pakistan and Iran and have a long tail of aftershocks of shallow to deep focal depths. The oceanic part of Arabian plate which is underthrusting Eurasian plate (northwards), contributes a major share in producing seismicity of low magnitude (ML< 4.0). GIS based analyses of earthquake data suggest that seismicity of Makran is not stationary but has been shifting over local coordinates in the last century. The other observation is there, may be a chance, that the dates of occurrence of major earthquakes (magnitude > 6 on Richter scale) has a relation with the rotation of moon (lunar dates) in Makran. Keywords: Seismicity, Makran, GIS, subduction, epicenter. Introduction Makran is considered a special case for the researchers not only because of its frequent low seismicity but also due to a hidden potential of shaking the ground with major earthquakes. Tectonic earthquakes release several megatons of stored seismic energy in few moments, and slam the man-made structures of minor to major standing over the brittle crust. The seismologists always are concerned with the sensitive areas of the earth, to find the causes of seismicity and its spatial distribution over the centuries. U.S. Geological Survey reports highlight the severity and causes of many killing earthquakes in recent years in the world. For instance, Mw9.1 Sumatra-Andaman earthquake (Dec. 26, 2004) resulted from oblique convergence of Indian plate and the Burmese microplate at Sunda trench, Chile earthquake (Feb. 27, 2010) of magnitude Mw8.8 occurred due to thrust-faulting in Peru–Chile Trench (where the oceanic Nazca plate subducts beneath the continental South American plate), and Mw 9.0 Tohoku-oki Japan earthquake (Mar 11, 2011) resulted from thrust faulting on or near the subduction zone at the plate boundary between Pacific and North American plates. The coastal areas of Makran (Jiwani, Gwadar, Pasni, Ormara and Gaddani) are important centers of sea-trade and socio-economic system of Pakistan, but also fall in tectonically active region where minor earthquakes occur almost every day. Mw 8.1 earthquake (Nov. 27, 1945) occurred on Makran coast (the epicenter was located seaward of Pasni village (Gates et al., 1977) which generated strong tsunami (waves 7-10 meters high) that terrified coasts of Pakistan, Iran and Oman (Beer and Stagg, 1946, Jacob and Quittmeyer, 1979; Pendse, 1946; Ambraseys and Melville, 1982; Byrne et al., 1992; Pararas-Carayannis G., 2006). The Awaran earthquake Mw 7.7 (Sep. 24, 2013) is the largest earthquake of the recent decade that jolted the southern / south-western margin of Pakistan. Makran offshore and onshore areas are tectonically active and seismically sensitive; they spread from Hermuz strait in Iran in the east to (near) Karachi (west) in Pakistan along Northern Arabian Sea (Fig. 1). Fig. 1. The study area (≈10 o wide x 5 o long). ©SEGMITE