Coastal-medium deformation and seismic hazards induced by the 2024 Noto Peninsula earthquake tsunami

The 1 January 2024 Mw7.5 Noto Peninsula earthquake generated a tsunami that spread across the East Sea (Sea of Japan). We investigate the tsunami effect on the coast in regional distances using tsunami-induced seismic wavetrains recorded by borehole broadband seismometers in the Korean Peninsula. The tsunami-induced seismic wavetrains are observed in the seismic stations near the coast. The seismic wavetrains are consistent with the tsunami records in tide gauges. The shared features in waveforms and spectral contents between the tsunami waves and the tsunami-induced seismic signals suggest that the energy origins are the same. The coastal loading of the tsunami induces ground tilting around the coast, producing long-period horizontal wavetrains that are polarized in coastline-perpendicular directions. The long-period tsunami-induced seismic energy deform the medium dynamically. Tsunami-induced deformation decreases with distance from the coast, being effective up to some depths. The amplitudes of tsunami-induced seismic signals are proportional to the amplitudes of tsunami waves. The tsunami-induced dynamic stress change reaches 0.81 kPa on the coast. A large runup height of a tsunami may trigger earthquakes around the coast.