TITLE:
Source Mechanisms of Recent Earthquakes in Southern Saudi Arabia: Detecting of New Seismic Sources
AUTHORS:
Ahmed Hosny, Abdullah Mousa, Khaled Yousef, Lotfy Samy, Hamada Sadallah
KEYWORDS:
New Seismic Sources, Local and Regional Stresses, Updating Seismic Hazard
JOURNAL NAME:
International Journal of Geosciences,
Vol.14 No.10,
October
19,
2023
ABSTRACT: Recently
in 2020, in southern Saudi Arabia three felt earthquakes occurred in Asir
region, in the Khamis Mushait, Ahad Rafidah, and AL-Shuqiq area, of magnitude
3.45, 3.1, and 3.5, respectively. The most interesting event was the earthquake that occurred in Khamis Mushait area, along a
lake formed behind the Tadhah Dam (~7 km), fearing any damage to the dam’s body
and the consequent destruction. Moment tensors for each event were computed for
determining fault plane solutions, seismic moment, moment magnitude (Mw) and
the CLVD ratio. In addition, the frequency contents in the waveforms of each
event were identified. The obtained focal mechanisms represent different styles
of faulting, normal movement with strike slip and strike slip with reverse.
These tectonic movements on faults parallel to the Red Sea refer to the
tensional forces due to the Red Sea rift system. These events occurred due to a natural tectonic movement, with
considering the Khamis Mushait event
as an induced event because of the lake behind the Dam. Many previous seismic hazard assessment studies have been
conducted in southern Saudi Arabia
without considering these recent seismic sources. Thus, our study provides new information related to detecting of new
active seismic sources, which contributes
to updating studies of seismic risk assessment in this region. In addition, our
study pushes us to establish other additional seismic stations around these new
seismic sources. This in turn will play a pivotal role in controlling seismic
sources and then reassessing the seismic hazard in
southern Saudi Arabia.