LOS ANGELES — The foreclosure crisis is getting worse as high unemployment and lackluster job prospects force homeowners in an increasing number of U.S. metropolitan areas into dire financial straits.

In Seattle, Houston and Chicago, cities that were relatively insulated from foreclosures early on in the housing bust, a growing number of homeowners are falling behind on mortgage payments and finding themselves on the receiving end of foreclosure warnings. Others have already seen their homes repossessed by lenders.

All told, foreclosure activity jumped in 149 of the country’s 206 largest metropolitan areas last year, foreclosure listing firm RealtyTrac Inc. said today.

The firm tracks notices for defaults, scheduled home auctions and home repossessions — warnings that can lead up to a home eventually being lost to foreclosure.

Job loss, rather than time-bomb mortgages resetting to higher payments, has become the main driver behind rising foreclosures.

“We’ve actually had a sea change in what’s causing foreclosures, from the overheated home prices and bad loans to a second wave of foreclosures actually caused by unemployment and economic displacement,” says Rick Sharga, a senior vice president at RealtyTrac.

The Houston-Sugar Land-Baytown metropolitan area in Texas saw its foreclosure rate jump 26 percent from 2009, the largest increase among the top 20 biggest metro areas, the firm said.

Seattle-Tacoma-Bellevue, in Washington, ranked second with an increase of nearly 23 percent, while the Atlanta-Sandy Springs-Marietta metro area in Georgia was third with a 21 percent bump.