Foreclosure filings rose 5 percent nationally in the third quarter to the highest three-month rate in almost five years, RealtyTrac Inc., of Irvine, Calif., reported yesterday.

One in every 136 U.S. housing units had a foreclosure filing during the quarter, according to RealtyTrac, which began tracking foreclosures in the first quarter of 2005.

Pennsylvania's and New Jersey's foreclosure numbers remained well below those in the so-called "sand" states: Arizona, California, Nevada, and Florida.

Pennsylvania was 34th nationally, with a filing for one in every 386 houses. No. 15 New Jersey had one filing for every 193 houses.

California, ranked first, had one filing for every 53 houses. The sand states, plus Illinois and Michigan, accounted for 62 percent of the filings in the quarter.

RealtyTrac chief executive officer James Saccacio said the increases indicated "that lenders may be starting to work through some of the pent-up foreclosure inventory caused by legislative delays, loan-modification efforts, and high volumes of distressed properties."

September foreclosures fell 4 percent from August, RealtyTrac reported.

Rising unemployment has replaced subprime loans as the major cause of mortgage delinquencies and foreclosures, experts and economists say.

"More and more foreclosure activity is related to job loss, and the wave of defaults caused by unemployment probably won't peak until the fourth quarter of 2010," RealtyTrac chief economist Rick Sharga said.

John Dodds, director of the Philadelphia Unemployment Project, said he believed failure to tame unemployment-related foreclosures would delay the recovery. He is pushing for direct government loans to jobless homeowners.

"The loss of 7.2 million jobs since the start of the recession complicates the crisis, as many jobless won't even have enough income for a loan modification to be effective," Dodds said.

Sharga and others warn of a "third wave" of foreclosure activity (subprime loans and unemployment being the first and second) starting in the third quarter of 2010, when exotic mortgages - option adjustable-rate mortgages and "Alt-A," or alternative-documentation, loans - begin to reset in earnest.

"There are about $2.5 trillion worth of these loans in the mortgage pool, and they will very likely default at record levels," Sharga said.

"Most borrowers elected either an interest-only or 'negative amortization' option," he said, which means they will owe as much or more than they did when they bought their homes, on properties that have depreciated at least 20 percent.

Many of these borrowers were, at best, marginally qualified and cannot afford higher payments, Sharga said.

Contact real estate writer Alan J. Heavens at 215-854-2472 or aheavens@phillynews.com.