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 e...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.展开更多
This study provides a comprehensive analysis of the recent volcanic seismic swarm in the southern Red Sea,specifically west of the Farasan Islands,southwest of Saudi Arabia.For a period of 7 days from July 29 to Augus...This study provides a comprehensive analysis of the recent volcanic seismic swarm in the southern Red Sea,specifically west of the Farasan Islands,southwest of Saudi Arabia.For a period of 7 days from July 29 to August 4,2025,the Saudi National Seismic Network(SNSN)recorded over 300 minor earthquakes,with local magnitudes(ML)ranging from 1.65 to 4.7 within latitude 16.6147 and longitude 41.2075(55 to 60 km west of the Farasan Islands).The swarm occurred in a vertical spreading at varying depths ranging from 4.5 to 30 km and included two earthquakes with local magnitudes of ML 4.33 and 4.7 at depths of 10 km and 13 km,respectively.The examination of the source mechanisms for the two largest earthquakes(ML=4.3,4.7)has revealed a normal mechanism that corresponds with the main direction of the Red Sea rift(northwest-southeast).Furthermore,the frequency contents of the majority of the swarm were measured at lower frequencies(below 1 Hz).According to the SNSN database,the recent swarm occurred in an area that had previously seen swarm activity and is located within a distance of 150 km from previous similar swarms that took place in 2007 and 2011 in the southern Red Sea.These similar swarms led to the formation of a new island on the northern edge of the Zubair Islands,which was called Al Jadid Island in 2011.The similarity between these swarms encompasses their number,depth range,vertical distribution,and eruption period to some extent.The results obtained indicated that the recent swarm is associated with volcanic activity,specifically a new magmatic intrusion that occurred beneath the middle of the southern Red Sea region.Thus,the possibility of the beginning of the formation of a new volcanic island in that location is raised.A hypothetical volcanic eruption scenario was developed,predicting heavy and light ash trajectories,potential threats to the Farasan Islands,southern Saudi Arabia,and other neighboring countries as a whole.展开更多
文摘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.
文摘This study provides a comprehensive analysis of the recent volcanic seismic swarm in the southern Red Sea,specifically west of the Farasan Islands,southwest of Saudi Arabia.For a period of 7 days from July 29 to August 4,2025,the Saudi National Seismic Network(SNSN)recorded over 300 minor earthquakes,with local magnitudes(ML)ranging from 1.65 to 4.7 within latitude 16.6147 and longitude 41.2075(55 to 60 km west of the Farasan Islands).The swarm occurred in a vertical spreading at varying depths ranging from 4.5 to 30 km and included two earthquakes with local magnitudes of ML 4.33 and 4.7 at depths of 10 km and 13 km,respectively.The examination of the source mechanisms for the two largest earthquakes(ML=4.3,4.7)has revealed a normal mechanism that corresponds with the main direction of the Red Sea rift(northwest-southeast).Furthermore,the frequency contents of the majority of the swarm were measured at lower frequencies(below 1 Hz).According to the SNSN database,the recent swarm occurred in an area that had previously seen swarm activity and is located within a distance of 150 km from previous similar swarms that took place in 2007 and 2011 in the southern Red Sea.These similar swarms led to the formation of a new island on the northern edge of the Zubair Islands,which was called Al Jadid Island in 2011.The similarity between these swarms encompasses their number,depth range,vertical distribution,and eruption period to some extent.The results obtained indicated that the recent swarm is associated with volcanic activity,specifically a new magmatic intrusion that occurred beneath the middle of the southern Red Sea region.Thus,the possibility of the beginning of the formation of a new volcanic island in that location is raised.A hypothetical volcanic eruption scenario was developed,predicting heavy and light ash trajectories,potential threats to the Farasan Islands,southern Saudi Arabia,and other neighboring countries as a whole.
