A Scripps scientist gave a recent update on continuing efforts to enhance coastal monitoring to better understand bluff failures to develop an early landslide warning system along San Diego’s coast.
Following a four-year study, Dr. Adam Young, a researcher and coastal geomorphologist at the Scripps Institution of Oceanography at UC San Diego, gave a virtual webinar on July 9 on coastal erosion and the dangers that it presents. A specialist in coastal erosion, sea-level rise, and hazard mapping, Young gained recent recognition for his research using ground tilt sensors to predict coastal cliff collapses days in advance.
Research reveals roughly 70% of the California coast is made up of eroding coastal cliffs. These cliffs are home to important infrastructure like highways, railways, coastal access points, energy facilities, and structures. They can be deadly to beachgoers when a cliff collapses.
The “California Coastal Landslide Early Warning Research” report found that a network of in-ground sensors can provide a reliable warning of impending, dangerous landslides with hours-to-days notice. But the report warned that more work is needed to formalize the findings into an actionable warning system.
Young discussed how we might go about implementing an early-warning system for coastal landslides during his webinar and a following Q&A session. He noted the state’s heavily eroded coast covers more than 1,000 miles and has the largest coastal population in the nation.
“The coastal economy is worth billions of dollars annually,” he said. “So, it’s incredibly important that we monitor our coastline to understand how it’s changing with time.”
To conduct research, Young and geophysicist Mark Zumberge instrumented key sites with advanced in-ground monitoring technology. The sensor technology used included tiltmeters, instruments often used to measure the movement of earthquake faults.
Young’s slideshow presentation depicted numerous landslides throughout the state, including some in San Diego County. He referenced one landslide in Torrey Pines State Park in La Jolla in order to “highlight the sudden collapse of massive amounts of (cliff) material that can fall down to our coast very suddenly.” He added, “There are at least 15 (landslide) events that have caused at least 25 fatalities in the state. Ten of these fatal events have happened in San Diego County.”
La Jolla frequently experiences coastal landslides and sea cliff collapses due to wave erosion, heavy rainfall and other factors. In January 2023, a massive landslide estimated at 150,000 cubic yards collapsed onto Black’s Beach. There have been emergency seawall projects to shore up eroding cliff edges and protect properties in Bird Rock. While Pacific Beach has experienced isolated bluff failures near Diamond Street, Mission Beach is completely flat and is instead prone to tidal flooding rather than coastal landslides.
Of the results of their four-year study of cliff collapses, Adams concluded:
“One of the things we learned is that we need to develop protocols for how to deal with this information. This is a new type of data that we made available, including some possible actions that could be done if a (cliff) failure is imminent.”
Young said possible future actions responding to imminent cliff collapse could include “temporarily closing part of a beach,” as well as developing a “landslide database for North San Diego County.”
Read the full report here: California Coastal Landslide Early Warning Research.
