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Abstract
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The Hojedk area in the southeastern Iran experienced three earthquakes during 12 days in December 2017. These events
occurred in proximity to a region that has experienced several moderate and large events in the past. In this paper, the role
of Coulomb stress changes in occurrence of the Hojedk cluster was investigated, and also the produced stress changes due
to these events on the surrounding and optimally oriented faults was calculated. Previous earthquakes (events in the Golbaf–
Sirch region, the Shahdad slip, and the Dahuiyeh–Zarand earthquake) imparted positive stress changes on the fault planes of
the Hojedk earthquakes, especially on the ruptured plane of the first main shock. The Hojedk first main shock triggered the
second one by imparting maximum stress changes of about 11.7 MPa on the fault plane of this event, and these two events
brought the third main shock to failure by producing more than 6.0 MPa stress changes on its ruptured plane. Among the
major active faults in the surrounding area, the middle part of the Nayband fault, northern part of the Golbaf–Sirch fault,
and southern part of the Kuhbanan fault received positive stress changes and southen parts of the Ravar and all parts of
the Chatrud faults received negative stress changes due to the Hojedk earthquakes. Furthermore, our results for correlation
between Coulomb stress changes and seismicity distribution showed that following the Dahuiyeh–Zarand earthquake, the
majority of the seismicity located on the positive stress area and Coulomb stress changes have a controlling role on the spatial
distribution of seismicity even after a decade. The occurrence of the Hojedk first main shock affects the spatial distribution
of aftershocks until the occurrence of the next main hocks. By triggering the next one, the stress patterns change in the area,
and seismicity follows from the stress patterns of the last event.
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