5:15 PM - 6:45 PM
[U15-P82] The maximum coastal uplift associated with the 2024 Mw 7.5 Noto Peninsula earthquake, central Japan, as revealed by abandoned sessile organisms on rocky coasts
The January 1 2024 Mw 7.5 Noto Peninsula earthquake resulted from rupture of multiple active reverse faults immediately off the northern coast of the Noto Peninsula, thereby causing extensive uplift along the coastline. We have conducted uplift measurements along the largest-uplift coastal section around Cape Saruyama and Cape Onagasaki, the amount of the maximum uplift being inferred at ~4–5 m by pixel offset analysis of ALOS-2 SAR images, where the access and field measurement were hampered by rugged coastal topography as well as numerous earthquake-induced landslides. Abandoned and living sessile organisms (Corallina pilulifera) on rocky coasts were used as uplift markers, and relative heights of upper limits of those two features were measured with a high-accuracy laser distant meter Laser Technology TruPulse 200X set on a tripod (error in vertical distance measurement is 1.7–4.3 cm in case of the horizontal distance of 10 m). Taking into account uncertainty in the determination of upper limits of abandoned and living sessile organisms (±~5 cm each), our measurement is associated with a total error of ±15–20 cm. The field measurement was conducted on fine-weather days from late March to early April when aftershock activity and sea conditions both calmed down.
Our uplift measurements at 24 sites along the ~10-km-long coastline reveal that the ~2.5-km-long section around Cape Saruyama was uplifted by >~5 m, with the maximum uplift of as large as 5.46 m ~0.6 km west of Yoshiura. The coastal uplift is significantly smaller around Cape Onagasaki, decreasing from 3.90 m north of Minazuki to 2.65 m at Kami-Osawa via 3.65 m at Cape Onagasaki. Amount and trend of the measured coastal uplift are largely consistent with those from the pixel offset analysis of SAR images. Our data would serve as basic information to examine location and slip distribution of the seismogenic fault immediately off the studied coast, as well as to study uplift history based on heights and ages of Holocene and Pleistocene marine terraces.
Our uplift measurements at 24 sites along the ~10-km-long coastline reveal that the ~2.5-km-long section around Cape Saruyama was uplifted by >~5 m, with the maximum uplift of as large as 5.46 m ~0.6 km west of Yoshiura. The coastal uplift is significantly smaller around Cape Onagasaki, decreasing from 3.90 m north of Minazuki to 2.65 m at Kami-Osawa via 3.65 m at Cape Onagasaki. Amount and trend of the measured coastal uplift are largely consistent with those from the pixel offset analysis of SAR images. Our data would serve as basic information to examine location and slip distribution of the seismogenic fault immediately off the studied coast, as well as to study uplift history based on heights and ages of Holocene and Pleistocene marine terraces.