Evaluation of factors controlling the spatial and size distributions of landslides, 2021 Nippes earthquake, Haiti

On 14 August 2021, a Mw 7.2 earthquake struck the Tiburon Peninsula, Haiti, with an epicenter at 18.434° N, 73.482° W and a focal depth of approximately 10 km. Combining multiple high-resolution satellite images and data of topographic, geological and seismological factors, this study evaluates the spatial and size distributions of the coseismic landslides triggered by this event and their corresponding controlling factors. The results show that the 2021 Mw 7.2 event, whose seismogenic fault is the Enriquillo-Plantain Garden Fault, triggered at least 8444 landslides over an area of ~2700 km². The total area of those triggered landslides was 45.6 km² and they were concentrated in the western section of the Tiburon Peninsula, especially within Pic Macaya National Park (6100 landslides occurred in or near this park, 72.2 % of the total), and 89.4 % of the landslides were distributed in the hanging wall area. High landslide concentrations (≥landslide frequency of 25/km²) are more prevalent in higher-elevation areas (≥1000 m). In areas at elevations ≥1000 m, more landslides are concentrated on the middle-lower mountain slopes; the landslide concentration is inversely proportional to the elevation and positively correlated with slope and local relief. The seismogenic fault area is typified by a high landslide concentration. Limestone is the dominant rock in the study area, as is the case for the 2010 earthquake, and rainfall has a positive relationship with the landslide concentration. For landslides whose areas ≥1000 m², the total number and area of coseismic landslides from the 2021 event are both larger than those from the 2010 event.