3:30 PM - 3:45 PM
[SSS11-11] Offshore seismogenic structure database of the Taiwan Earthquake Model (TEM)
Keywords:Seismogenic structures, Seismic hazard, Earthquake magnitude, Long-term slip rate, Earthquake recurrence interval
Taiwan is an active orogenic belt with many active structures and frequent earthquake activities. Understanding the seismogenic characteristics of these active structures before earthquake occurrence is crucial for reducing the losses caused by earthquakes. Currently, the Taiwan Earthquake Model (TEM) project has published 45 on-land structures, and such information has been used by the government and many scholars for disaster preparations. However, despite reports of active structures and many historical earthquakes offshore Taiwan, there is still a lack of a comprehensive database of offshore seismogenic structures.
In this study, we integrated results from previous geological and geophysical studies to determine the possible locations and subsurface geometry of offshore seismogenic structures. At present, we have identified and mapped 54 offshore structures, each with estimated parameters such as possible magnitude, long-term slip rate, and earthquake recurrence interval. Using three empirical equations, all structures have the potential to produce earthquakes exceeding magnitude 6.5. The results show that the area with fast slipping (~10-20 mm/yr) structures is located in the hanging wall of the two subduction systems, whereas structures with lower slip rates (~0.1-2 mm/yr) are located in the post-collision zone off northeast Taiwan. Higher slip rates correspond to shorter earthquake recurrence intervals, such as the 100-year scale of structures near the subduction zone and the 10,000-year scale in the northern offshore region. Due to the limitation of seismic data quality and topographic resolution, these structural parameters still have large uncertainties and need to be refined. However, with the establishment of this offshore seismogenic structure database, we anticipate to enhance earthquake hazard assessments for Taiwan.
In this study, we integrated results from previous geological and geophysical studies to determine the possible locations and subsurface geometry of offshore seismogenic structures. At present, we have identified and mapped 54 offshore structures, each with estimated parameters such as possible magnitude, long-term slip rate, and earthquake recurrence interval. Using three empirical equations, all structures have the potential to produce earthquakes exceeding magnitude 6.5. The results show that the area with fast slipping (~10-20 mm/yr) structures is located in the hanging wall of the two subduction systems, whereas structures with lower slip rates (~0.1-2 mm/yr) are located in the post-collision zone off northeast Taiwan. Higher slip rates correspond to shorter earthquake recurrence intervals, such as the 100-year scale of structures near the subduction zone and the 10,000-year scale in the northern offshore region. Due to the limitation of seismic data quality and topographic resolution, these structural parameters still have large uncertainties and need to be refined. However, with the establishment of this offshore seismogenic structure database, we anticipate to enhance earthquake hazard assessments for Taiwan.