Datensatz

Zusammenfassung

The Philippine Sea plate is subducting from the Suruga and Nankai troughs beneath southwest Japan. Great interplate earthquakes occurred repeatedly along the troughs. In the near future, Nankai trough earthquake will occur and be possible to become nationwide disaster. Early detection of seismic waves and tsunamis by instrument observation is important in order to reduce earthquake and tsunami disaster and one of the advantages of the earthquake and tsunami observation on the seafloor contributes to early detection of them compared to inland observation. The sea area from the off the Kochi Prefecture to Hyuga-nada, which is correspond to the western half of the focal region of the anticipated Nankai trough earthquake, is a blank area of the seafloor observation networks. In 2019, the National Research Institute for Earth Science and Disaster Resilience started a project to develop the Nankai Trough Seafloor Observation Network for Earthquakes and Tsunamis (N-net) in this blank area. The N-net has two systems, a coastal system and an offshore system, to ensure redundancy, with 18 observation nodes in each system. In this study, we investigated how fast the direct detection of seismic waves and tsunamis can be achieved when N-net data can be acquired. We conducted the calculation of the travel time for seismic waves and tsunamis by assuming point sources. As a result, we found the detection of seismic wave and tsunami was expected to be earlier approximately 20 seconds and approximately 20 minutes at the maximum considering the N-net data, respectively.