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Sinkholes and mudslides | Is San Diego at a saturation point with all the rain?

More rain is coming; can we expect more sinkholes and mudslides around the county? CBS 8 talked with an expert about how ground saturation plays a factor.

SAN DIEGO — Can we expect more sinkholes and mudslides around the county with more rain? CBS 8 talked with an expert about how ground saturation plays a factor. 

“Well, you know the rain we’ve been getting month after month, that’s big for saturation. It’s a cumulative effect,” said Dr. Pat Abbott, professor emeritus of geology at San Diego State University. “It’s not like we had a solid two months of sunshine to pull all that water out of the earth and evaporate it.  It just keeps being recharged, recharged, and the deeper that saturation, the longer it will take to get it out.” 

During recent storms, sinkholes have formed across the county, including a massive one in Cardiff that has increased with each passing rainstorm. Another sinkhole opened up in Scripps Ranch at Jerabek Park last week.  Both were caused by ruptured stormwater pipes that eroded the soil underneath.  

“When pipes crack or rust away, the water gets out, it starts removing the sand, the earth, and eroding and creating the pit that the surface then falls into,” said Abbott. 

When an atmospheric river came through last week, a hillside in Vista began to shift and slide, damaging homes at the Green Valley Mobile Home Park. 

In San Clemente, a bluff gave way to a landslide, causing the evacuation of homes and apartments nearby. 

“It would be the rain saturating into the ground, cause that weight to increase enough, and clay minerals are probably in there, wetting, expanding, weakening the rock itself, enough that a downhill slide begins,” said Dr. Abbott. “Every hillside, every hill slope is an equilibrium situation.  Gravity’s trying to pull everything down; it’s constantly pulling.” 

As San Diegans gear up for another round of heavy rain, we may likely see more sinkholes form and hillsides start to shift across the region. 

“Another saturating rain, another opportunity to pump more water, to pull more water underground and make those hillsides more prone to failure than they have been,” said Dr. Abbott. 

WATCH RELATED: Light, scattered showers Monday before strong storm arrives Tuesday 


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