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Assessment of Landslide and Debris Flow Impacts in Puerto Rico

Hurricane Maria generated more than 40,000 landslides in Puerto Rico, devastating infrastructure and property.

Landslide impact assessment: tasks and benefits 2018

Landslide hazard assessment and risk communication following Hurricane Maria  

Heavy rainfall from Hurricane Maria triggered tens of thousands of landslides in Puerto Rico in September 2017. Immediately following the passage of the storm, the U.S. Geological Survey (USGS) began collecting data to assess the extent and severity of landslides and their impacts (Bessette-Kirton and others, 2018). In the subsequent weeks and months, USGS scientists provided technical assistance to response efforts and conducted field visits. The 2018 Disaster Supplemental Appropriation (P.L. 115-123) enabled the USGS to work with a range of partners to provide science information to support recovery and rebuilding decisions. Additional resources also allowed the USGS to bolster program capabilities by:

  1. accelerating the development of new methods and models for assessing landslide hazard from lidar data;
  2. enabling new capacity for landslide monitoring and support for National Weather Service (NWS) alerting, and
  3. providing an opportunity to develop and integrate risk-communication principles into scientific information development and delivery.
Screen shot of the landslide susceptibility map Puerto Rico
Landslide susceptibility map Puerto Rico.

The new landslide susceptibility map for the main island of Puerto Rico (Hughes and Schulz, 2020) is the centerpiece of the project. Developed in cooperation with the University of Puerto Rico Mayagüez (UPRM), the map is a state-of-the-art application of lidar topography and landslide-mapping data. Accessible via web-based map viewer the map and underlying data are being used by the Puerto Rico Planning Board and others to inform recovery, rebuilding, and emergency management decisions. Supplemental funding also accelerated development of geospatial tools that can be applied using lidar data to evaluate not just the locations where landslides begin, but where they will travel and ultimately come to rest. These tools bridge a methodological gap and are expected to be widely adopted by partners at state geological surveys and international geological organizations for mapping hazard and risk associated with shallow, rapidly moving landslides such as debris flows.

Two monitoring stations were installed in landslide-prone areas in central Puerto Rico to collect data on the soil moisture and rainfall conditions that generate landslides. Analyses of the data collected over two wet seasons (Thomas and others, 2020) provides the basis for an expanded effort in cooperation with UPRM and NOAA’s National Weather Service (NWS). The network is expected to ultimately include as many as 15 stations and when operational will be used to support landslide forecasting and alerting. The acute hazard and cooperation with UPRM provide the opportunity to engage students in the development what will be the most-comprehensive landslide monitoring network in the United States and a testbed for expanded cooperation with the NWS.

Center map shows landslide locations. Hills slope from sides down to center of figure with descriptive labels and arrows.
The University of Puerto Rico Mayagüez, the Natural Hazards Center at the University of Colorado Boulder, and the USGS Landslide Hazards Program collaborated to create educational materials for residents of Puerto Rico to learn about how to prepare for, mitigate, respond to, and recover from landslides. Pages from “Landslide Guide for Residents of Puerto Rico “ are shown in this figure. The project’s products describe landslide risk in a format accessible to a wide variety of audiences, from children to emergency managers. All the educational materials, including the “Landslide Guide for Residents of Puerto Rico,” can be accessed via the Landslide Hazard Mitigation Project website:

A risk communication and community engagement campaign with partners at the Natural Hazards Center at the University of Colorado Boulder and UPRM is supporting greater awareness of landslide hazards and USGS science products. Developed first in Spanish, a guidebook for landslide hazards provides actionable information accessible for the residents of Puerto Rico. Derivative products including animations, story maps, educational worksheets, and radio scripts were created to reach a broader audience. The partnership provided an opportunity to develop and test an approach to engage communities and other stakeholders in the development and delivery of landslide hazard information. The work led to the development of a set of generally applicable principles for collaborative risk communication including cultural competence, ethical engagement, inclusive decision making, and reciprocity (West and others, 2021). The partnerships, connections, and cultural competence developed through this aspect of the project also greatly enhanced the ability of the USGS to assist response and recovery efforts following the Southwest Puerto Rico earthquake sequence that began in late 2019.


Return to 2018 Supplemental Appropriations Activities.

Additional Resources

Puerto Rico Landslide Hazard Mitigation Project

Two hydrologic monitoring sites (Utuado and Toro Negro) for the Landslides/Debris flow impact assessment provide real-time data.

Geologic Hazards Science Center 

Geology Minerals Energy and Geophysics Science Center 

Smith, J.B., Thomas, M.A., Ashland, F., Michel, A.R., Wayllace, A., and Mirus, B.B., 2020, Hillslope hydrologic monitoring data following Hurricane Maria in 2017, Puerto Rico, July 2018 to June 2020: U.S. Geological Survey data release.

West, J., Davis, L., Lugo Bendezú, R., Álvarez Gandía, Y.D., Hughes, K. S., Godt, J.W., & Peek, L., 2021, Principles for collaborative risk communication: Reducing landslide losses in Puerto Rico: Journal of Emergency Management, v. 19, no. 8, p. 41-61


Toro Negro, Puerto Rico Landslide Monitoring Station

Toro Negro, Puerto Rico Landslide Monitoring Station

Utuado, Puerto Rico Landslide Monitoring Station

Utuado, Puerto Rico Landslide Monitoring Station