Comparison of coseismic landslide inventories from the 2024 Hualien Earthquake, the 2022 Taitung Earthquake, and the 1999 Chi-Chi Earthquake

On April 3, 2024, a strong earthquake with amagnitude ML 7.2 struck Shoufeng Township in Hualien County, Taiwan, causing 18 fatalities due to coseismic landslides. Coseismic landslides have long been a key topic in global geohazard research. To understand their characteristics and causes, it is essential to establish an objective and comprehensive inventory of landslides. Moreover, comparing coseismic landslide inventories from different earthquakes could understand how topographic, seismic, and geological characteristicsinfluence the spatial distribution of these landslides. The 2024 Hualien earthquake induced 3,232 coseismiclandslides with total area of 41.74 square kilometers.These landslides mostly occurred in regions where the peak ground acceleration exceeded 250 gal and the peak ground velocity surpassed 30 cm/s. They were primarily concentrated in areas composed of marble and schist, and predominantly faced east or southeast, with slope angles mainly ranging from 40°-60°.This study further compares the coseismic landslide inventories from the 2024 Hualien earthquake (ML7.2), the 2022 Taitung earthquake (ML6.8), and the 1999 Chi-Chi earthquake (ML 7.6). Except for the 2024 Hualien earthquake, the numbers of coseismic landslides in the other events are 306, and 9,272, respectively, with total landslide areas of 0.93, and 127.8 square kilometers. The slope aspects of the other two earthquakes are southeast and south mainly. The slope gradients range from 40°-60° and 40°-50° for the 2022 Taitung earthquake and the 1999 Chi-Chi earthquake. In terms of lithology, the coseismic landslides associated with the 2022 Taitung earthquake and the 1999 Chi-Chi earthquake occurred in areas characterized by schist and epiclastics, andsandstone and conglomerate, respectively. Therefore, these three coseismic landslide inventories show the influence of different geologic background and topographic relief. This study presented the topographic, geologic, seismic diffrences of coseimic landslide inventories with the regions between metamorphic rock and sedimentary rock in Taiwan.   Keywords: 2024 Hualien Earthquake, 2022 Taitung Earthquake, 1999 Chi-Chi Earthquake, Coseismiclandslide inventory.