Puerto Rico landslides: U-M expert available

EXPERT ADVISORY

Hurricane Fiona knocked out power across Puerto Rico and unleashed floods and landslides. With its mountainous terrain, frequent earthquakes and a tropical climate prone to extreme weather, Puerto Rico is known as a hotspot for landslides.

Hurricane Maria struck the island in September 2017 and triggered more than 70,000 landslides across the island. A University of Michigan expert is available to discuss Puerto Rico landslides.

Geomorphologist and geophysicist Marin Clark is a professor and chair in the Department of Earth and Environmental Sciences. She measures and interprets Earth surface processes that shape mountains over geological time and that trigger disasters during earthquakes and major storms. In particular, she studies the mechanisms that initiate landsliding and develops models that predict future landslide hazards.

A NASA landslide project team, which includes Clark’s research group and collaborators at the University of California, Berkeley, is preparing to support the U.S. Geological Survey and the University of Puerto Rico Mayaguez in landslide assessment once the storm passes. Clark’s team anticipates collaborating by using satellite images and ground observations to identify and interpret patterns of landsliding related to the storm, in particular across the region affected by a series of earthquakes in 2020.

Clark led a scientific workshop in May that was focused on landslide disaster response and planning in Puerto Rico. The workshop was sponsored by NASA, the U.S. Geological Survey and the University of Puerto Rico, Mayaguez. Attendees considered the separate and combined effects of earthquakes and strong storms on landslide hazards, using past events in Puerto Rico as guidance.

"Hurricane Fiona hit the southern coast of Puerto Rico hardest, in a region still recovering from a sequence of strong earthquakes in 2020 that caused destructive landslides and ground motion,” Clark said. "That was the main focus of the workshop in May, to understand how these different forces-earthquakes and big storms-interact to multiply landscape hazards.

"We know from other regions in the world that earthquakes destabilize slopes for a period of many years, making steep hillsides more susceptible to landsliding during strong storms than they would be otherwise. Therefore, heavy rains from Fiona may do more damage than they would have done if the earthquake sequence had not recently occurred.”