LAKEPORT, Calif. — Residents of a Northern California subdivision that is sinking into a hilltop are hoping Gov. Jerry Brown approves a county request for disaster assistance.

So far, the Lake County public works director and an expert hired by the county have been unable to determine why groundwater is bubbling to the top of the hill where homes were built 30 years ago.

Since late March, eight homes have cracked apart and been abandoned, and owners of another 10 are under threat of imminent evacuation.

Public Works Director Scott De Leon says the entire 30-home subdivision will have to be abandoned if his crews can’t stop the moving earth from collapsing.

The region 100 miles north of San Francisco was formed by volcanoes and earthquakes.