5:15 PM - 6:45 PM
[U15-P87] Topographic change in the seafloor off the northeast coast of Noto Peninsula due to the 2024 earthquake
Keywords:Tectonic landform, Multibeam bathymetry survey, Submarine mass movements
On January 1, 2024 at 16:10, a seismic event with a magnitude of Mj7.6 occurred in Suzu City, Ishikawa Prefecture, resulting in significant damage due to the earthquake and tsunami in the coastal areas, Toyama Prefecture, and Niigata Prefecture. While the epicenter of this earthquake is still under investigation by various institutions, there have been cases where the epicentral area was presumed to be along the northern coast of the Noto Peninsula, ranging from the western coast to the vicinity of Toyama Deep-Sea Channel in the east, based on the distribution of aftershocks. On the other hand, the offshore active fault zone along the northern coast of the Noto Peninsula has been identified by the National Institute of Advanced Industrial Science and Technology and others, consisting of multiple segments with a length of approximately 95 km, but there is no mention of the northeastern offshore area. Furthermore, according to the Ministry of Land, Infrastructure, Transport and Tourism, there is another fault with reverse inclination located to the northeast, but its relevance as the fault responsible for the epicenter of this earthquake remains unclear. If the epicentral area of this earthquake extends to the northeast offshore of the Noto Peninsula, there is a possibility of leaving traces of varying topography reflecting the displacement caused by the fault on the seafloor. Moreover, it is possible to confirm the involvement of each fault in the earthquake based on these traces. Therefore, when high-resolution topographic information was obtained through multibeam bathymetry targeting the northeast of the Noto Peninsula, no tectonic landform in terrain were observed near the F42 tsunami source area set by the Ministry of land, Infrastructure, Transport and Tourism. In addition, Futagi and Matsushi (2022) studied the development process of seafloor topography based on the interpretation of geological and geophysical structures using high-resolution bathymetry data in the offshore area of Suzu, Noto Peninsula. As a comparison of the pre- and post-earthquake changes in topography can be made in the specified area, we have realized that the scale of submarine mass movements activated by an earthquake of magnitude Mj7.6 or so is limited.