Investigating Topographic Changes Associated with the 2024 Noto Peninsula Earthquake Using Affordable CLAS-GNSS and Hand-held Laser Scanner, and Verifying Their Effectiveness

In recent years, inexpensive, small, and lightweight measurement instruments compatible with high-precision positioning such as Centimeter-Level Augmentation Service Global Navigation Satellite System (CLAS-GNSS) and hand-held laser scanners have become available. These devices have the potential to enable rapid and efficient surveying of topographic changes immediately after disasters. The 2024 Noto Peninsula earthquake (Mj 7.6) caused a range of topographic changes from coseismic uplift to slump scarps away from the source fault. In this study, we use a CLAS-GNSS instrument and a hand-held laser scanner to investigate the topographic changes caused by the earthquake and discuss their effectiveness. To constrain coseismic uplift, we analyze the difference between elevations obtained from the pre-earthquake high-resolution digital elevation model and the post-earthquake CLAS-GNSS survey. The results show that coseismic uplift occurred over a wide area along the northern coast of the Noto Peninsula, especially in the northwestern part of the peninsula, with a maximum coseismic uplift of 4.5 m. Using the pre-earthquake high-resolution digital elevation model as a reference, we combined CLAS-GNSS and handheld laser scanner measurements to investigate slump scarps in the post-earthquake topography. The results show that scarps more than 2.5 m high occurred, as well as backward flexural deformation. These results are consistent with those obtained from studies of dead marine sessile organisms, satellite image analyses, and structure from motion multi-view stereo. The equipment used in this study should enable fast and efficient on-site investigations of topographic changes that occur during disasters.