10:00 AM - 10:15 AM
[SSS11-05] The relationship between the 2024 Noto-hanto, Japan, earthquake and short active faults nearby
★Invited Papers
Keywords:Noto-hanto earthquake, active fault
The 2024 Noto-hanto earthquake with a magnitude of Mw 7.5 ruptured approximately a 150-km-long ENE-trending active fault mapped offshore along the northern coast of the peninsula. The earthquake was accompanied by numerous widespread aftershocks, including a magnitude 6.1 earthquake that occurred 8 minutes after the mainshock. One concern involves large off-fault aftershocks associated with minor short active faults mostly mapped along the southeastern peninsula coast, such as the Sakami fault, Fuku-ura fault, Togigawa fault, and others. Most of these faults are shorter than 5 km at the surface and characterized by range-facing scarplets.
From the viewpoint of seismic hazard assessment, these minor faults are considered as M~7-class seismogenic hidden faults that may be crucial for subsequent triggered earthquakes following the Noto-hanto earthquake. We suspect their seismogenic potentials by modeling the coseismic deformation of the mainshock and its cumulative effect, suggesting the buildup of the SE-tilting landform over the past half a million years. Our calculated coseismic volumetric strain, in the order of contraction 10^-4 to 10^-5 in and nearby the southeast coast, is significant. Assuming about 100 times of events similar to the 2024 earthquake, this strain is large enough to generate shallow bending moment faulting.
While further detailed analysis and speculation are required, we tentatively conclude that these minor faults are structures associated with major earthquake events and are limited to depths shallower than ~3 km, making them not capable of producing a large earthquake.
From the viewpoint of seismic hazard assessment, these minor faults are considered as M~7-class seismogenic hidden faults that may be crucial for subsequent triggered earthquakes following the Noto-hanto earthquake. We suspect their seismogenic potentials by modeling the coseismic deformation of the mainshock and its cumulative effect, suggesting the buildup of the SE-tilting landform over the past half a million years. Our calculated coseismic volumetric strain, in the order of contraction 10^-4 to 10^-5 in and nearby the southeast coast, is significant. Assuming about 100 times of events similar to the 2024 earthquake, this strain is large enough to generate shallow bending moment faulting.
While further detailed analysis and speculation are required, we tentatively conclude that these minor faults are structures associated with major earthquake events and are limited to depths shallower than ~3 km, making them not capable of producing a large earthquake.