Landslides triggered by the August 14, 2021, magnitude 7.2 Nippes, Haiti, earthquake

Abstract

The August 14, 2021, magnitude 7.2 Nippes, Haiti, earthquake triggered thousands of landslides on the Tiburon Peninsula. The landslides directly caused fatalities and damage and impeded response efforts by blocking roads and causing other infrastructure damage. Adverse effects of the landslides likely will continue for months to years. This report presents an assessment of potential postearthquake landslide-related geologic hazards for the Tiburon Peninsula and a preliminary map of the landslides triggered by the earthquake. This hazard assessment is based on an emergency analysis of the currently available, postearthquake satellite imagery. In this report, we highlight specific areas of concern that may benefit from more detailed assessment and longer-term monitoring. Our mapping efforts revealed that at least 4,893 landslides were triggered across the Tiburon Peninsula by the earthquake and subsequent rainfall from Tropical Cyclone Grace. We also observed hundreds of landslide deposits potentially restricting flow in rivers and streams. In addition, we observed landslides that likely affected roads by rendering them impassable or susceptible to subsequent damage from existing landslides. Because of the preliminary nature of this report and the limits of remote analyses, additional investigation and monitoring would be beneficial to accurately determine the threat posed by these hazards to people and infrastructure.

Generating landslide density heatmaps for rapid detection using open-access satellite radar data in Google Earth Engine

“…While writing this paper, a major M w 7.2 earthquake struck on 14 August 2021 in Haiti and caused widespread landsliding in the southwestern part of the country (Martinez et al, 2021a). The earthquake epicenter was near Nippes, Haiti (∼ 120 km west of Port-au-Prince) (https://earthquake.…”

“…We posted our landslide heatmap on the NASA's Jet Propulsion Laboratory and California Institute of Technology in collaboration with the Earth Observatory of Singapore (EOS). The SAR-based products are particularly important because cloud cover prevented full optical-based landslide mapping for weeks after the earthquake (Martinez et al, 2021a).…”

“…Due to the cloud cover, only a ∼ 300 km 2 area had partial visibility, and ∼ 525 landslides were mapped (https: //maps.disasters.nasa.gov/arcgis/apps/MinimalGallery/ index.html?appid=3b785d8e1ff943e59a9810f67181b8d3, last access: 4 March 2022). The USGS then released a larger preliminary rapid landslide inventory that included 3625 landslides over a ∼ 5000 km 2 area between 17-23 August 2021 made from Planet and Maxar optical imagery and published a final inventory of 4893 landslides made from Sentinel-2, WorldView, and Planet imagery in December 2021 (Martinez et al, 2021a; see "Code and data availability"). We found good agreement between our SAR-based landslide heatmap and the area of highest landslide density mapped with optical imagery, providing further evidence that our SAR-based approach is well suited for rapid response following major catastrophic landslide events (Fig.…”

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

“…We could identify only about 100 minor dams (with a volume of less than 50,000 m 3 , according to our estimate, based on the maximum surface area value of about 5000 m 2 measured for the largest observed dam and a related maximum possible thickness of 15 m, compared with the local morphological setting) after the August 2021 main shock, most of which had disappeared before the end of October 2021; and, only a few dozens of them were impounding temporary lakes. In this regard it should be noted thatMartinez et al (2021), who had also mapped landslides triggered by the 2021 Nippes earthquake (4893, according to their open file report), have outlined almost 300 (at least partial) landslide dams after the event. However, they also indicate that most of them failed a few days after formation; still, at the time of publication of their open file report in December 2021, they consider 35 of the remaining dams as potentially hazardous.…”

“….2.1 Landslide inventory statistics Table1presents an overview of general landslide inventory statistics, for both the 2010 and 2021 events.The numbers in the first row show that apparently fewer landslides have been triggered in August 2021 (considering also the number of 4893 landslides published in the open file report byMartinez et al, 2021) than in January 2010. At least two inventories, the one byHarp et al (2016) and the one ofXu et al (2014), include far more landslide outlines (23,567 for the first, 30,828 for the second) than our catalogue for 2021 (7091).…”