The earthquake on April 16th 2013 was a result of normal faulting at a depth of approximately 80km. Tectonics in the region are dominated by the collision of three major tectonic plates; the Arabian and Indian plates are converging with the Eurasian plate at rates of 37mm/year and 40mm/year, respectively.
No fewer than four major tectonic plates (Arabia, Eurasia, India, and Africa) and one smaller tectonic block (Anatolia) are responsible for seismicity and tectonics in the wider Middle Eastern region. Geological development of the region is the result of a number of tectonic processes that include subduction, large-scale transform faulting, compressional mountain building and crustal extension.
Mountain building in northern Pakistan and Afghanistan is the result of compressional tectonics associated with collision of the India plate and the Eurasia plate. Continental thickening of the northern and western edge of the India subcontinent has produced the highest mountains in the world, including the Himalayan, Karakoram, Pamir and Hindu Kush ranges. Earthquake activity and faulting found in this region, as well as adjacent parts of Afghanistan and India, are due to collisional plate tectonics.
More information about this event and the regional geology can be found at the USGS Earthquake Hazards Program.