Here's a somber statistic for Silicon Valley: Foreclosure activity increased at a faster clip in Santa Clara County last year than in any other California county, a foreclosure information service said Tuesday.

Foreclosure filings rose 239 percent from 2007 to 2008, according to a report from Default Research, a Pennsylvania company that gathers its data from public records. A total of 18,610 properties in the county entered into some stage of foreclosure in 2008, said the company, up from 5,491 in 2007.

Santa Clara County witnessed last year's fastest growing foreclosure problem partly because the county had relatively few foreclosures in 2007 compared to other large counties, said Serdar Bankaci, founder of Default Research. But as home prices in some parts of the county fell sharply in 2008, mortgage delinquencies and foreclosures here increased steeply.

"The southern part of California really got hit harder earlier on," he said. "It was just kind of a lag. We're seeing a lot of the Northern California areas were hit hard later in 2008."

Bay Area counties such as Contra Costa and Solano — popular with first-time buyers who were able to buy with small down payments during the housing and mortgage boom — saw more dramatic increases in foreclosure filings between 2006 and 2007 than did Santa Clara. Santa Clara County, in effect, played catch-up with that trend in 2008.