Geotechnical Extreme Event Site Reconnaissance in Puerto Rico after the Passage of Hurricane Maria

Abstract

The National Weather Service classified Hurricane Maria as a strong Category 4 Hurricane on the Saffir-Simpson hurricane wind scale at the time of its landfall in Yabucoa, Puerto Rico, U.S.A., on September 20, 2017. The immediate aftermath of Hurricane Maria was a devastated island with at least 64 people killed, severe infrastructure loss, a devastated electric power grid, and numerous geotechnical failures related to the intense rainfall and strong winds associated to this extreme event. This paper will summarize the event timeline and the geotechnical consequences of Maria’s path across Puerto Rico. The impacts of Hurricane Maria on infrastructure and geomorphology are documented through the data and observations of the engineers and geologists that comprised the Geotechnical Extreme Events Reconnaissance (GEER) team. The main reconnaissance mission took place between October 25 and November 6, 2017, followed by a second field component involving terrestrial LiDAR surveys and UAV photogrammetry performed January 8 to 11, 2018.

This paper summarizes observations on geotechnical impacts such as: the Guajataca Dam spillway failure, coastal erosion events (including foundation failures due to coastal erosion in Córcega, Rincón), bridge abutment scour failures, over 2,000 landslides along the PR highway system (e.g., along the PR-10, region of Lares, Barranquitas and Utuado); foundation failures, and other failures related to this destructive hurricane. Rainfall-induced landslides in Puerto Rico have been a serious recurring problem (e.g., Jibson, 1987; Larsen and Simon, 1993; Larsen and Santiago-Roman, 2001; Pando et al., 2005) observed in the different physiographic regions of the island as result of Maria and other hurricanes such as Hortense (1996), Georges (1998), and Debby (1999). The passage of Hurricane Maria triggered thousands of landslides, with the most common type of failure mode consisting of shallow debris flows. However, many deeper-seated failures were also observed, typically at sites with a road fill and blocked drainage. The geotechnical failures presented in this article provide insight to help identify typical modes of failure and to help the engineering community adapt and improve design and construction practices to improve resiliency of our infrastructure and lifelines.