Home foreclosures continued to drop in Southern California in February, with rates in the greater Valley varying widely, according to a report released Thursday. There were 7,734 foreclosures in the six-county region, down 31 percent from the same month last year, according to RealtyTrac, an Irvine real estate data firm. On a month-to-month basis, the rate dropped about 10 percent since January. In Los Angeles County, one in every 3,235 homes was in foreclosure during the month. In the greater Valley, Palmdale topped the list, with foreclosures in one out of every 367 homes. The other major Antelope Valley city of Lancaster also continued to struggle, with one out of every 429 homes in foreclosure. Daren Blomquist, vice president at RealtyTrac, said while the numbers have continued to improve, there is a growing concern over what he calls zombie foreclosures —owner-vacated properties that have been in the foreclosure process an average of 1,031 days. “The biggest threat from foreclosures going forward is properties that have been lingering in the foreclosure process for years, many of them vacant with neither the distressed homeowner or the foreclosing lender taking responsibility for maintenance and upkeep of the home — or at the very least facilitating a sale to a new homeowner more likely to perform needed upkeep and maintenance,” he said in a statement. Other Valley communities with high foreclosure rates include Sunland, with one in every 530 homes; Santa Clarita, with one in every 548 homes; and Sylmar with one in every 593. Among Valley communities with few foreclosures were La Canada-Flintridge, with one in every 3,626 homes; Newbury Park, with one in every 2,217; and Burbank, with one in every 1,930.