Impulsive Source of the 2017 M _W=7.3 Ezgeleh, Iran, Earthquake

Abstract

On 12 November 2017, a M _W =7.3 earthquake struck near the Iranian town of Ezgeleh, at the Iran‐Iraq border. This event was located within the Zagros fold and thrust belt which delimits the continental collision between the Arabian and Eurasian Plates. Despite a high seismic risk, the seismogenic behavior of the complex network of active faults is not well documented in this area due to the long recurrence interval of large earthquakes. In this study, we jointly invert interferometric synthetic aperture radar and near‐field strong motions to infer a kinematic slip model of the rupture. The incorporation of these near‐field observations enables a fine resolution of the kinematic rupture process. It reveals an impulsive seismic source with a strong southward rupture directivity, consistent with significant damage south of the epicenter. We also show that the slip direction does not match plate convergence, implying that some of the accumulated strain must be partitioned onto other faults.

Key Points

• The Ezgeleh earthquake ruptured a flat thrust fault in the Zagros fold and thrust belt

• Kinematic slip modeling reveals a highly impulsive source with southward directivity, possibly causing the large damage in the area

• The direction of coseismic slip suggests a strain partitioning between thrust and unmapped strike‐slip faults