The torrents of water coming from the sky are having ripple effects on the cliffs that hold up some of California’s most expensive real estate. In the first two months of the year, nearly 18in of rain has fallen in the southern California area, about 8in above normal to date – and more is on the way this week.The California governor, Gavin Newsom, declared a state of emergency in eight counties covering more than 20 million people, and flash-flood warnings were issued for parts of Los Angeles, Santa Barbara and San Luis Obispo counties.In wealthy coastal cities such as San Clemente and…