Large cracks have opened up at Sunset Cliffs near PNLU. Signs at Sunset Cliffs urge visitors to keep off unstable areas of the park. Photo by Jim Grant
Sunset Cliffs is on (a) crack.
So much so that part of the Ocean Beach landform, which developed a sizable split beneath Point Loma Nazarene University during the last storm event, could come tumbling down.
Perhaps soon, according to Prof. Pat Abbott. “The crack literally is wide enough to stick your arm in — if you dare,” said Abbott, a San Diego State University geology professor emeritus and author of a bestselling textbook, “Natural Disasters,” published by McGraw-Hill. “It looks to me like the crack is widening.”
Noting cliff erosion is a natural process and that one of the forces at work, gravity, is “pulling every minute, every day,” Abbott said it's not a question of whether the cracked cliff section will one day fall but when.
“It could happen any day of any year,” he said, asking, “At what instance does gravity win? A lot of times, it is not predictable. If we get a real good rainstorm that gets into that crack and causes it to open up a little bit more, it could put it past the point of no return.”
Abbott noted ocean waves constantly pounding the cliffs, and especially high tides during the winter season and storm surges, factor into ongoing erosion of oceanside cliffs.
Will there be any advance warning when the university cliff face gives way?
“More than likely it will just fall without warning,” Abbott said. “When gravity is tired of pulling, it will be game over.”
Sunset Cliffs, which straddles the Ocean Beach and Point Loma areas, is composed of two different landforms, according to Abbott. The geologist described the lower-level rock as “hard sandstone about 76 million years old,” adding, “It's compacted and cemented together.”
“That older rock formed about 3,000 feet deep in the ocean is part of the uplift of the Peninsula caused by the Rose Canyon fault system,” Abbott said, adding that the upper, newer level of rock is much more loosely compacted and therefore much more susceptible to erosion.
Concerning the potential threat of the cliff below the university falling, Abbott said that is a very real possibility, though he added, “The beach below PLNU is not heavily used, only used by surfers,” whom he said “might be walking under that cliff when it goes,” in which case, he added, “It would be a fatality. There is a fatality every few years.”
The geology professor noted that it is extremely difficult, if not impossible, to predict when an eroding landform, like the cliff at the university, will finally give way, though he noted the current El Niño may have something to do with that.
“We expect some really big storms with big waves the next couple of months,” he said. “So there's a chance we'll have some cliff failures. It's the same every day. The odds may be higher, though, of this occurring during this couple-month period.”