Introduction Background
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IntroductionBackgroundThe Zagros Mountains are a long mountain range in Iran, northern Iraq, and southeastern Turkey. The mountains are the most seismically active in the world, with a length of more than 1,600 km (Figure 1.1a). The Zagros range begins in northwestern Iran and roughly follows Iran's western. The orogenic continental collision between the Arabian and Eurasian plates, which started 10–35 Ma ago, is the cause of the active deformation (Hessami et al., 2001; McQuarrie et al., 2003; Pirouz et al., 2017). This collision formed a series of folds and thrusts within the mountain range, accommodating about one-third of the current plate convergence rate, about 20 to 30 millimeters per year (Masson et al., 2005) (Vernant et al., 2004a). The Alborz and Greater Caucasus mainly accommodate the remainder, and Kopet Dag mountain ranges to the north and the subduction of the South Caspian Basin further to the north (Hollingsworth et al., 2008). During the Phanerozoic, the thrusting caused by collisions created a shallow folded sedimentary cover 6–15 km thick and an overlying crystalline basement hosting seismically active thrust faults. A weak detachment horizon may exist at the bottom of the sedimentary sequence, possibly rooted in thick evaporate deposits found in diapers in the SE Zagros (McQuarrie, 2004). The Zagros range can be divided into zones based on topography, geomorphology, stratigraphy, and seismicity. The high Zagros to the northeast, which averages 1.5–2 km in elevation, and the Folded Belt (SFB), which runs along the frontal part of the mountain range. The SFB is divided along strike into the low-lying Kirkuk and Dezful embayments and the mountainous Lurestan and Fars arcs. (Nissen et al., 2011). History records several earthquakes in the region during 956, 958, 1150, and 1226 AD, each of a magnitude of 5.9 to 6.5. There have never been any earthquakes greater than 7 along the Zagros. The seismic moment has been released along the Zagros in the last 100 years (Berberian, 1995). The study area lies about 140 km southwest of Kermanshah province and only a few kilometers east of the Iran‐Iraq border. It is located at latitude and longitude 34.4513937, 45.8612066. Topographically, the area lies just 550 meters above sea level in the Zagros folded zone. There are two landforms in the research region. The northern mountainous landform (known locally as Mian-Call Mountain) and the majority of the area covered by the flat plain landform, consisting of the Alvand River and the alluvial sediments that this river deposits (Figure 1.1b). Figure (1.1): Location maps (a) Location of Zagros, (b) location of the study area with tectonic and major faults of the Zagros Mountains. The main strike fault is depicted in black. The red lines represent the potential locations of “master blind thrusts. The ALOS-2 data is shown in white rectangles, and the Sentinel-1A data is depicted in cyan rectangles. Color ramp is the earthquake focal mechanism with a magnitude value of 7-2 Download 0.84 Mb. Share with your friends:
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