Mapping of active and presumed active faults in Afghanistan by interpretation of 1-arcsecond SRTM anaglyph images

Abstract

Afghanistan is a tectonically complex zone developed as a result of the collision between the Eurasian plate and the Indian plate to the southeast and the Arabian plate to the south. The active tectonics of the country is distinguished by a wide zone of crustal deformation. There is no large-scale active fault map in Afghanistan, which is essential for seismic hazard mitigation. I, therefore, mapped active and presumed active faults mainly based on interpretation of 1-arcsecond SRTM anaglyph images and shaded relief map. The map reveals that there are significant active faults across the country. In consideration based on the available data and geomorphic criteria, 22 faults are considered seismically active. The result from the mapping represents that three dominant types of structures (left-lateral strike-slip, right-lateral strike-slip, and thrust faults) characterized the interior of Afghanistan. Then the active fault map was combined with earthquake catalog data to interpret the seismic hazard and define earthquake sources based on focal mechanisms and distribution of earthquakes. To contribute to the understanding of seismic hazard, the paper outlines regions with similar neotectonic constraints and observations of type and age of faults that generate background seismicity. I delineated four seismic source zones: (1) east-northeastern, (2) Afghanistan-North Pamir, (3) Northern Afghanistan platform, and (4) middle and southwestern Afghanistan. The east-northeastern seismic zone is the most seismically active and has more crustal earthquakes in the country. This zone is cut by large active and potentially active faults, and Chaman fault is the most significant left-lateral fault that produced five historical surface ruptures.