Shoreline advance due to the 2024 Noto Peninsula earthquake

Abstract

Large earthquakes can instantaneously reshape coastal landforms owing to fault zone ruptures that uplift the Earth's surface. On January 1, 2024, in the north of the Noto Peninsula, central Japan, an Mj7.6 (Mw7.5) earthquake occurred, triggering coastal uplift of up to 4 m. To measure the resulting shoreline advance, we analyzed orthophotos taken before and after the earthquake, focusing on two bays in the northwest of the Noto Peninsula where the largest uplift occurred. In response to the uplift, the shoreline advanced by up to 200 m, increasing the total area of the coastal plains by 0.46 km 2 . The maximum shoreline extension occurred in the midsection of both bays, while the extension at the edges was less than 20 m, possibly reflecting the shoreface topography and bathymetry existing before the uplift. The uplift exposed previously undersea rocks, forming new coastal plains and extending river channels. Our results indicate that coastal landforms such as sandy beaches, coastal plains, shore platforms, and the sediment budgets of feeding drainage systems were substantially altered by this earthquake, and a long recovery period is anticipated. Our findings serve as a crucial benchmark for tracking future changes in shorelines in response to coastal landform adjustments.