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Scripps Oceanography scientists get $2.5 million to study cliff collapse and improve warnings

State parks officials posted this photo on Aug. 31, 2019, of the aftermath of a bluff collapse at Torrey Pines State Beach.
State parks officials posted this photo on Aug. 31, 2019, of the aftermath of a bluff collapse at Torrey Pines State Beach, between Tower 1 and Flat Rock Beach in La Jolla.
(Courtesy of California State Parks)

A program to accelerate the study of cliff collapse got a financial boost this month when state Assembly Bill 66 was signed into law. It provides $2.5 million for a three-year study led by scientists at La Jolla’s Scripps Institution of Oceanography that will look into the processes of cliff failure that lead to collapse. The study ideally will help improve the warning system for the public.

The bill was introduced by Assembly member Tasha Boerner Horvath, whose 76th District includes north coastal San Diego County. It was spurred by an Aug. 2, 2019, bluff collapse at Grandview Beach in Encinitas in which three women were killed. It is considered among the deadliest cliff collapses in the county in recent memory.

“With the passage of AB 66, we are one step closer to saving lives along California’s coast,” Boerner Horvath said. “Bluff collapses are a constant threat to coastal neighborhoods in northern San Diego County and across the California coast, presenting the risk of fatalities, injuries and millions of dollars in damage to vital infrastructure.”

Coastal geomorphologist Adam Young and geophysicist Mark Zumberge are leading the study.

“This funding is great, it’s a significant boost in this research, so we are really excited to have this money and be able to do these studies in the future,” Young said.

He said there are several processes that lead to cliff failure, such as waves eroding the bottom of a cliff and creating instability that something like heavy rain can turn into collapse. But there are gaps in the research that will be filled by this study, he said.

“When a cliff failure occurs, it may occur over a time period; it’s not necessarily an instantaneous event,” Young said. “It tends to creep toward the ocean and then fail catastrophically. We may be able to measure that deformation as it starts the process of the failure.”

Young said the project has two main parts: putting sensors in the cliffs at specific sites (one will be in Encinitas and the other potentially in Del Mar) and creating a database for the region.

Zumberge said the funding from the bill “will allow the installation of sensors whose capabilities exceed what was available in the past, and in so doing we hope to learn more about what happens before a slope becomes a slide.”

Measures at La Jolla’s Scripps Institution of Oceanography and Birch Aquarium aim to protect marine life while oceanographers assist in wind and currents forecasts.

According to Scripps Oceanography, scientists will install optical-fiber equipment called strainmeters at key locations along the cliffs. The strainmeters, a technological advance developed at SIO for seismic research, can measure earth movements at the scale of microns.

Additionally, researchers will deploy tiltmeters, the development of which was pioneered by SIO engineers. Tiltmeters can measure microscopic changes in spatial orientation of masses of earth that potentially can provide predictive capability to those who monitor slope stability.

The second phase of the study will develop a database of when landslides occur regionally.

“We only do surveys once or twice a month, in some places once or twice a year, but that doesn’t tell us when the failures are occurring,” Young said. “A lot of my research in the past has been trying to understand how fast our coast is eroding and why, but when surveys are that far apart, it doesn’t tell you … when the landslide occurred and you have no way of knowing what triggered it.

“We want to increase the frequency of the surveys so we can get a better idea of what happened and when and the environmental conditions around that time period to see if there is something specific we can tie to the timing of the landslide ... such as a really heavy rainfall event.”

The study is set to begin Jan. 1, with immediate first steps being technology and permit acquisition and hiring staff.

“The main goal is to improve safety on our coastline. We don’t want people to get hurt or injured on our coastline,” Young said. “We hope this research will provide more information about these processes so we can inform the public of the hazards.”

— The San Diego Union-Tribune contributed to this report.