Reflection seismic, gravity, magnetic, and InSAR analysis of the Chaman Fault in Pakistan

This study presents new insights on the Chaman Fault System that connects deformation in the Makran and Himalayan collision zones. The Chaman Fault is similar to 850 km long, and shear strain is concentrated in a densely populated region between 29 and 32 degrees N. Three earthquakes with Mw similar to 5 occurred in May, July, and August of 2016 along a segment the of the Chaman Fault at 30.5 degrees N. This study uses Interferometric Synthetic Aperture Radar, reflection seismic, gravity, and magnetic data to understand earthquake distribution along the Chaman Fault and to characterize its subsurface structure. Reflection seismic profiles across the Chaman Fault show that it dips similar to 80 degrees towards the west and has been imaged down to similar to 7 km. Gravity and magnetic data integrated with six seismic profiles document a sedimentary basin up to similar to 5 km deep that contains an intrusive body adjacent to the Chaman Fault. The seismic data also show the southern segment of the Chaman Fault widens at a depth between similar to 2.5 and 4 km that correlates with the fault locking depth. Interferometric Synthetic Aperture Radar results from 2006 to 2011 observes slip rate distributions that explain the increasing frequency of earthquake activity along the locked segment of the Chaman Fault at similar to 30.5 degrees N.