Geologists with the USGS said the potential for landslides in Pacifica has now reached a risky level, adding to the concerns homeowners along the coast have over erosion.
Just this month, Pacifica has seen about five inches of rain. Scientists now said the ground in the area is maxed out.
"The more rain we get, the more worry," resident Kim Mahart said.
Mahart moved to Pacifica for the sprawling mountain view. Mahart and her family have lived at the base of San Pedro Valley Park for a little over a year.
"It's still pretty, but it's dangerous obviously," Mahart said.
USGS geologists have buried a water measuring device just over the hill from Rosita Road.
"This is an experiment," geologist Jonathan Stock said. "Nature runs the experiment."
When heavy rains move into the Bay Area, Stock tracks two very important ratings: the percentage of water that has already been absorbed in the soil and the amount of standing water near the surface.
"We're right at the cusp if it were to rain half an inch an hour," Stock said. "Past experience shows we would see landslides."
Stock said for the first time since the measuring device was installed four years ago. The levels have reached a "high risk zone" for potential landslides.
"In the last decade, we've almost forgotten a little bit the dangers that lurk in the hillsides," Stock said.
The geologist stopped short of predicting a landslide, but said more research is needed before the study can be used as a warning system.
Families who call Pacifica home are eager to know more about the hills in their backyard.
"I wish I knew how to prepare for something like that,"
Meanwhile, an apartment complex on 320 Esplande that has been red-tagged by the city is scheduled to be demolished by crews on Saturday morning. The demolitions is scheduled to take up to five days, officials said.
The apartment complex has been vacant since 2010 and is at risk of crumbling over the eroding cliff, city officials said.