Focal Mechanism of the Focal Mechanism of the M(N) ۵.۴ and M(N) ۵.۳ Earthquakes of December ۲۰۲۲ in Boshroyeh, South Khorasan using P-wave first motion polarity and waveform modeling

On December ۱۳, ۲۰۲۲, an earthquake occurred at ۱۷:۴۴:۲۶ local time, equal to ۱۴:۱۴:۲۶ UTC, in Boshroyeh region, located in South Khorasan province. For this earthquake, the magnitude of MN=۵.۴ and the epicentral coordinates of ۵۷.۱۳° east longitude and ۳۳.۹۶۵° north latitude were reported. This earthquake was felt in the cities of Ferdows and Tabas Nair. About ۱۰ aftershocks have been reported for this earthquake. On the ۴th of December ۲۰۲۲, another earthquake with a magnitude of MN=۵.۳ shook Boshroyeh area at ۱۶:۵۴:۳۶ local time equal to ۱۳:۲۴:۳۶ UTC. The purpose of this research is to determine the focal mechanism of earthquakes of MN=۵.۴ on December ۱۳, ۲۰۲۲ and MN=۵.۳ on December ۲۴, ۲۰۲۲ in Boshroyeh, South Khorasan. In this study, first, the focal mechanism of the earthquake (Nodal Planes) was determined using the First P-wave motion polarity method, then by inverting the moment tensor using waveform modeling at the stations recorded, the focal mechanism of the mentioned earthquakeswas determined. The focal mechanism obtained for both earthquakes indicates a strike-slip fault with a verticalcomponent. Considering the trend of the faults in the region and the surface distribution of the aftershocks of the twoearthquakes in question, it seems that the Esfandiar fault is the cause of the two aftershocks and their aftershocks.

Keywords:

Focal mechanism , P-wave first motion polarity , Waveform modeling , Boshroyeh , Nodal planes