Earthquake faulting and bedding thrust associated with the Tabas-e-Golshan (Iran) earthquake of September 16

The Tabas-e-Golshan earthquake of magnitude Ms-- 7.7 occurred in a region of east central Iran known to have been quiescent for at least 11 centuries. The shock was associated with 85 km of discontinuous thrust faulting at the surface along an existing but unrecognized late Quaternary fault (the Tabas Fault). Nearly all the surface breaks followed the obvious scarps created by the previous faulting. An extensive zone of "bedding thrusts " (bedding-plane slip) was also developed in the Neogene clay deposits of the overthrust block, east of the main fault zone. Minimum vertical uplift (throw) and slip measured at about 150 and 300 cm, respectively. The deformation caused by this earthquake indicates crustal thickening of the region, i.e. uplifting along the earthquake fault. The Tabas Fault is one of the principal structures by which the western flank of the Shotori mountains is raised about 2 km above the alluvial deposits of the Tabas compressional graben. It is a multi-role deep-seated Precambrian fault and one of the major features during Paleozoic and Mesozoic, in the western part of th