Sea Bluff Collapses at Blacks Beach
by J Nandhini | Updated Jan 23, 2023
Lifeguards informed NBC 7 on Friday afternoon that there was a collapse of a bluff at Black's Beach.
Black's Beach is situated north of La Jolla Shores, with cliffs that reach hundreds of feet in height. The collapse, which happened a few hundred yards south of the Torrey Pines Glider Port, is believed to be 250 feet wide and 25 feet high. Lifeguards are currently monitoring the situation closely, using pickup trucks located near the base.
No injuries have been reported from the collapse, which occurred around 2 p.m. on Friday. Eyewitnesses told NBC 7 that the incident happened relatively slowly, allowing anyone nearby to move away safely before any danger was present.
The officials estimated the size of the collapse to be 150,000 cubic yards.
A surfer who witnessed the collapse told NBC 7, "For about 10 minutes chunks of rock falling along the ledge, then just massive piles started falling and collapsing onto the beach so slowly." He also added that "I think it happened so slowly, you'd see so many chunks starting to fall that everybody was backing up already."
After the collapse, lifeguards closed off the debris field and also shut down the La Jolla Walking Trail where it intersects the Citizen Trail.
Dr. Pat Abbott, Professor of Geology Emeritus at San Diego State University said, "This is the largest landslide we've seen in this area in many years, but it's actually a continuation of an old one that didn't finish sliding."
According to Dr. Abbott, a significant collapse also occurred in that location almost 41 years ago to the date. He also added that many of the cliffs near San Diego's beach communities have experienced some form of failure at one point in time.
Dr. Abbott also stated that "Five times since 1995, there have been sea cliff failures in San Diego County that resulted in one to five deaths each time."
Dr. Abbott said that collapses are not frequent but they do occur, particularly when certain conditions align.
Dr. Abbott said that factors such as high sea cliffs, erosion at the base from waves, constant gravitational force, less sand on the beach during winter, and higher tides, all contribute to the increased likelihood of cliff failure.
Rainfall is also a factor that can cause cliff failure, according to Dr. Abbott.
Dr. Abbott said that "When the rocks are saturated with water, they become weaker and heavier, which enhances the force of gravity pulling on them during these periods."
According to Dr. Abbott, collapses such as this will continue to occur and while there may be methods to try and prevent them, it may not be worth the effort.
Dr. Abbott raised a question "We can take those cliffs and we can grade them back and flatten them. We can put up big concrete walls and we can do all those things that would fundamentally spoil the environment. So, do we live with mother nature and learn to adapt or are we going to battle her and try to combat and turn everything to concrete and heavy rocks?"
