SAN DIEGO - Jeanne Plante didn't pay much attention this summer as city engineers worked to figure out why the busy road up the hill from her house was ominously cracking apart.
Then the ground below the road suddenly collapsed last week, taking four houses with it and burying two others. Now, she and her neighbors want to know why it took so long for the city to recognize a major landslide risk was imminent.
"If it happened to them, what's to stop it from happening to us?" she said shortly after she was allowed to return to the $1.7 million gray-stone property, which sits about a hundred feet downslope from the toe of Wednesday's landslide.
City geologists say the collapse has apparently stabilized now that the stress has been relieved on the weak earth, which caved beneath a 50-yard stretch of road. But answers explaining why the collapse happened are harder to find.
Four houses sank into the 20-foot-deep fissure, while tons of dirt carrying fully grown pines and eucalyptus shoved a wall of road asphalt and broken curb into two houses on the next street below. Seven houses were so severely damaged residents can't even get inside, and 22 more are off-limits except with safety escorts.
City officials estimate the damage could be $48 million - $26 million for broken sewer and water mains, and $22 million for private property losses.
The area where the collapse occurred, Mount Soledad, is an upper-middle-class residential neighborhood that boasts views of mountains to the east and a short commute to the surf spots and tony restaurants of downtown La Jolla.
Residents who live near the slide zone criticized the city for not warning that a slide was possible after concerns about water main leaks, sinking curbside meters and creeping gaps in the sidewalk first cropped up in July.
"We are helpless," said Joseph Tsai, a retired engineer who moved to Mount Soledad 12 years ago. "It depends on the city to address the problems."
City officials have said they were considering new vehicle weight limits and other stopgap measures early in the week, but didn't realize a collapse was imminent until shortly before it happened.
Residents of the four houses directly atop the collapse were advised late Tuesday not to sleep in their houses; homeowners whose properties were buried said they had no advance notice.
"There was no indication they were at risk," said Bill Harris, a city spokesman.
Harris said the city is conducting an investigation of the events leading up to the collapse. No decision had been made about how to make sure the hillside remains in place, and the city has no plan to broaden testing to determine whether other parts of the neighborhood are threatened.
Experts said the likelihood of a second similar collapse is low, but smaller slides may be possible as the earth settles.
Meanwhile, pavement has been cracking on streets in another nearby neighborhood, and residents have hired geologists in an attempt to determine whether a similar slide is imminent there.
At the sight of last week's slide, newly exposed earth may be weakened if rain passes through the area before any shoring devices are put in place. Water saturation, whether from the sky or from nearby residents watering their lawns - something they were told to stop doing weeks ago - can make the surrounding hillside heavier and raise the risk of further failures.
Experts said the key to preventing future problems will be to get underneath the weak soil layer and replace everything above it with material that can carry the weight of houses and streets and utility lines - a project that might entail reinforcement with pylons or buttresses and the installation of water pumps to prevent the earth from getting heavier when rains come or pipes burst.
"Landslides are reparable," said Tim McCrink, a geologist with the California Geological Survey. "If there's enough money and enough interest, they can be fixed."
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