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|December 11, 2019|
More cliff collapses expected with rising seas, says USGS
ENCINITAS, CA - Days after a cliff collapse killed three people in Leucadia, California, there are new concerns about beach bluff failures.
A portion of Grandview Beach remains blocked off to the public. Pat Abbott, Ph.D., and Professor Emeritus of Geology at San Diego State University thinks a larger part of the beach should be off limits.
“What you want to particularly look for is where the cliffsides are weak. You recognize those by fractures in the rocks, or where the waves undercut the slope,” said Abbott.
The U.S. Geological Survey (USGS) estimates cliffs like the ones in Encinitas could erode dozens of feet by the end of the century because of rising sea levels. Abbott says there will be significant erosion, but he questions the accuracy of the USGS estimate.
“The first question is, what’s the sea level going to be in the year 2100? No one really knows. If you don’t know what the sea level is you’re not going to know what the cliffs are going to do,” said Abbott.
Based on the fractures in the cliffs in Leucadia, Abbott believes another collapse is imminent.
“It could be today, it could be in 25 years,” said Abbott. “Everyone who has cliffside property, enjoy it, but don’t think your grandkids are going to get to enjoy it.”
There are several cliffs collapses in San Diego county every year, but most don’t make any news. Abbott says all cliffs will retreat because gravity keeps pulling on them, and waves are undercutting them at the base, but they don’t retreat the same or for the same reasons.
The hard rock that is exposed on the Leucadia cliffs is 45 million years old, but there are other local cliffsides that are much younger and have rocks that are much younger.
“If we go to Del Mar near the railroad tracks, where we keep having these things collapse all the time, those are rocks that are only thousands of years old. The rock that the train tracks are on, you can crush it with your hands because the rock is so weak,” said Abbott.
Abbott knows locals and tourists will keep enjoying the scenic shoreline, but he has simple advice for beachgoers.
“I wish people would just look up at the cliffs and look: Is this fractured? Is there an overhang there? And keep walking until you find a spot where you don’t find that,” said Abbott.
Encinitas Lifeguards say they contact an average of 3,000 people every year, to warn them about the cliffs. There are also warning signs posted at all public beach access points. (Source: KNBC)
Story Date: August 18, 2019