Earthquake-induced landslides in Haiti: analysis of seismotectonic and possible climatic influences

peer reviewedAbstract. First analyses of landslide distribution and triggering factors are presented for the region affected by the 14 August 2021 earthquake (Mw=7.2) in the Nippes Department, Haiti. Landslide mapping was mainly carried out by comparing pre- and post-event remote imagery (∼0.5–1 m resolution) available on Google Earth Pro® and Sentinel-2 (10 m resolution) satellite images. The first covered about 50 % of the affected region (for post-event imagery and before completion of the map in January 2022), and the latter were selected to cover the entire potentially affected zone. On the basis of the completed landslide inventory, comparisons are made with catalogs compiled by others both for the August 2021 and the January 2010 seismic events, including one open inventory (by the United States Geological Survey) that was also used for further statistical analyses. Additionally, we studied the pre-2021 earthquake slope stability conditions. These comparisons show that the total number of landslides mapped for the 2021 earthquake (7091) is larger than the one recently published by another research team for the same event but slightly smaller than the number of landslides mapped by a third research team. It is also clearly smaller than the one observed by two other research teams for the 2010 earthquake (e.g., 23 567, for the open inventory). However, these apparently fewer landslides triggered in 2021 cover much wider areas of slopes (>80 km2) than those induced by the 2010 event (∼25 km2 – considering the open inventory). A simple statistical analysis indicates that the lower number of 2021 landslides can be explained by the missing detection of the smallest landslides triggered in 2021, partly due to the lower-resolution imagery available for most of the areas affected by the recent earthquake; this is also confirmed by an inventory completeness analysis based on size–frequency statistics. The much larger total area of landslides triggered in 2021, compared to the 2010 earthquake, can be related to different physical reasons: (a) the larger earthquake magnitude in 2021, (b) the more central location of the fault segment that ruptured in 2021 with respect to coastal zones, (c) and possible climatic preconditioning of slope instability in the 2021 affected area. These observations are supported by (1) a new pre-2021 earthquake landslide map; (2) rainfall distribution maps presented for different periods (including October 2016 – when Hurricane Matthew had crossed the western part of Haiti), covering both the 2010 and 2021 affected zones; and (3) shaking intensity prediction maps

Detailed map, displacement, paleoseismology, and segmentation of the Enriquillo-Plantain Garden Fault in Haiti

International audienceThe Enriquillo-Plantain Garden Fault (EPGF) ruptured several times in Haiti, producing large historical earthquakes (e.g., 18 October 1751, 21 November 1751, and 3 June 1770). Their location and lateral extents are poorly known. The most devastating one, the Mw7, 12 January 2010 earthquake should have been the occasion to constrain the fault kinematics and geometry, unfortunately no significant surface rupture was observed. Here, combining LiDAR data, high-resolution aerial photographs, geological map and observations in the field, we revisited the fault map at a large variety of scales to improve the assessment of seismic hazard associated with the EPGF. This detailed mapping allowed us to target several sites for paleoseismic trenches. We carried out paleoseismological investigations in the Clonard pull-apart basin during which one trench was opened perpendicular to the fault. That trench showed stratigraphic evidence for one paleoearthquake. Radiocarbon dating in a dry and buried stream led to the conclusion that the paleoearthquake might be that of 1770. Then, based on kilometric-scale geometric complexities, we showed that the EPGF was composed of more than four segments, each capable to generate Mw>7 earthquakes. Finally, we identified several geological and geomorphic markers of long-term deformation along the fault. The geological offsets of ~40 km, ~15 km and ~8 km from west to east support the idea of an eastward propagation of the EPGF

Seismotectonics of southern Haiti: A new faulting model for the 12 January 2010 M7 earthquake

International audienceThe prevailing consensus is that the 2010 Mw7.0 Haiti earthquake left the Enriquillo– Plantain Garden strike-slip Fault (EPGF) unruptured but broke unmapped blind north-dipping thrusts. Using high-resolution topography, aerial images, bathymetry and geology we identified previously unrecognized south-dipping NW-SE-striking active thrusts in southern Haiti. One of them, Lamentin thrust (LT), cuts across the crowded city of Carrefour, extends offshore into Port-au-Prince Bay and connects at depth with the EPGF. We propose that both faults broke in 2010. The rupture likely initiated on the thrust and propagated further along the EPGF due to unclamping. This scenario is consistent with geodetic, seismological and field data. The 2010 earthquake increased the stress toward failure on the unruptured segments of the EPGF and on neighboring thrusts, significantly increasing the seismic hazard in the Port-au-Prince urban area. The numerous active thrusts recognized in that area must be considered for future evaluation of the seismic hazard

Geologic reconnaissance and crack data of the 2021, Mw7.2, Haiti earthquake

This repository contains the structured data associated with the cracks observed during the fieldwork following the 14 August 2021, Mw 7.2, Haiti earthquake. The files rupture_latspread.csv and SaintFleur_etal_G3_TabS1.xls are equivalent and hold the raw data. The file SaintFleur_etal_G3_TabS2.xlsx is clean/refined data obtained after processing. Please see our paper in G-cubed

Intersectional Impacts of the 2021 Mw 7.2 Nippes, Haiti, Earthquake from Geotechnical and Social Perspectives

The Mw 7.2 Nippes, Haiti, earthquake occurred on 14 August 2021 in Haiti's southwest peninsula and in the midst of significant social, economic, and political crises. A hybrid reconnaissance mission (i.e., combined remote and field investigation) was coordinated to document damage to the built environment after the event. This article evaluates two ground-motion records available in Haiti in the context of the geology of the region and known areas with significant damage, such as Les Cayes. We also present a new map of time-averaged shear-wave velocity values to 30 m depth (VS30) for Les Cayes and Port-au-Prince based on the geostatistical approach of kriging and accounting for region -spe-cific geology proxies and field measurements of VS30. Case studies of ground failure obser-vations, including landslides and liquefaction triggering, are described as well as the intersection of social and engineering observations. Maps depicting this important inter-section are provided to facilitate the assessment of how natural hazards and social con-flicts have influenced the vulnerability of Haiti's population to earthquakes