>> now to news of our natural world . we learned an estimated 32 million people were forced to leave their homes and the world last year for weather-related reasons. tonight it appears to be happening again in northern california where some people in a neighborhood that's been there for 30 years are looking for a new place to live because the ground, the environment underneath their houses is sinking. nbc's ayman mohyeldin is with us this evening. good evening.

>> reporter: nestled above the hills of wine country in northern california are beautiful homes and eidyllic resorts. a mystery is causing homes to crumble and it has local officials and residents here puzzled.

>> this is about as far as we should probably go snx it started with a few cracks in the walls. within weeks scott spivey's dream home began slipping away p.m. the doors wouln't shut. everything started getting out of synch and the house stated moving.

>> reporter: his house along with the homes of his neighbors in this subdivision a hundred miles from san francisco are sinking. it's caught everyone here by surprise.

>> 11 years of living here. we had to get out in 48 hours . it was stressful.

>> reporter: so far seven homes abandoned and six more being evacuated. local officials are baffled as to the cause.

>> at this point we don't know what the source of the flight is. that's making it difficult to be able to institute any sort of permanent recovery or some sort of conclusion to getting the slide to stop.

>> reporter: two leaks in the county water system were found and plugged and sewer lines are being redirected. even mail delivery is suspended. the area is just too unstable. while officials try to figure out what's causing the slide, the homes and dreams of residents are slowly slipping away . for this retiree it means the loss of much-needed rental income.

>> i spent $70,000 a year and a half ago to remodel my house. it's really sad.

>> reporter: local officials and residence debits here want the area declared an emergency. that brings in experts to determine the cause and more importantly gives the local residents funds to help them get back on their feet. right now they are not too optimistic. brian?

>> thanks for that report.