Homes in a Lake County subdivision are being abandoned as they slowly sink into the ground.

At least eight homes have already been abandoned, and another ten are on notice of immediate evacuation in the hilltop community about 100 miles north of San Francisco.

One Lake County couple, who have lived in their home for 11 years, first noticed cracks in their walls in March. Within two weeks, their 600-square-foot garage broke off of the house and fell ten feet below the street. Unlike the instantaneous Florida sinkholes, these homes can move "many feet in one day and just a fraction of an inch the next."

The hill under the community, with sweeping views of Clear Lake and Mount Konocti volcano, is now threatening to swallow all 30 houses in the subdivision, and officials aren't quite sure why.

"That's the big question," county public works director Scott De Leon told the Examiner. "We have a dormant volcano, and I'm certain a lot of things that happen here (in Lake County) are a result of that, but we don't know about this."

Further confounding officials has been the appearance of plentiful water "atop the hill in a county with groundwater shortages." One cause may be the area's damaged public water system, which received repairs on Friday. At least two leaks were repaired by experts, and officials continue to monitor the system with periodic leak detection tests.

But the slowly sinking homes appear to exceed the boundaries of the Postal Service creed (along with Brooklyn and Saturdays), and USPS is refusing to deliver mail to the homes.

"It's a slow-motion disaster," resident Randall Fitzgerald told reporters.

[via, photo via Getty]