Pennsylvania's chronically underused Mine Subsidence Insurance Program will lower its premiums Jan. 1, which could induce more of the 1 million property owners whose land lies above the mines to buy coverage.

The first big rate reduction in the 47-year history of the nonprofit, state-run insurance program will lower premiums on residential properties 28 percent, and on commercial, office, agricultural and manufacturing structures up to 65 percent, said Ed Motycki, chief of the state Department of Environmental Protection's mine subsidence section.

Although premium rates are already low, Mr. Motycki said, just 56,900 property owners hold policies that cover their risk of catastrophic damage to homes and other structures.

"We haven't heard too many complaints about the price as the reason people haven't bought it," Mr. Motycki said. "But we are in the position to do rate reductions, so we're doing it."

Mr. Motycki said an Illinois actuarial firm studied the nonprofit program's finances -- which show a $61 million fund balance -- and recommended the reductions in residential annual premiums that now cost $88.50 for $100,000 of insurance. Those premiums will fall to $63.80.

Nonresidential premiums will be reduced from $354 a year for $100,000 of insurance to around $125, depending on the type of nonresidential use.

Mine subsidence occurs when pillars of coal left behind by traditional deep mining operations to support the mine roof and prevent surface subsidence deteriorate over time and collapse. Such mines, some 200 years old, extend throughout 43 of the state's 67 counties, including much of Allegheny County.

Last year, the program paid out a total of $1.37 million statewide on approximately 40 subsidence claims, Mr. Motycki said. Since 1961 when the program started it has paid $23 million in claims.

Despite the widespread risks posed by subsidence, most commercial homeowners and nonresidential property policies do not cover damage from subsidence that can cause surface land movement, crack building foundations and walls or produce breakouts of mine water that can flood structures.

Pennsylvania, recognizing that public exposure, established the first state-run, nonprofit subsidence insurance program in the nation, but few property owners signed on.

Only about 10,000 subsidence policies are in effect in the anthracite coal region in the northeastern part of the state where the mines have long since played out and shut down and subsidence is a concern. In densely populated Allegheny County, where old mines underlie many Pittsburgh neighborhoods and municipalities, property owners hold 27,600 subsidence policies, more than in any other county in the state.

To publicize the program and get more people to sign up, the state has increased its annual advertising budget to $400,000, four times as much as it spent in 2000. It has also expanded homeowners' coverage to include subsidence-caused damage to fences, walls, patios, driveways and in-ground swimming pools.

By the end of the year, homeowners will be able to log on to the program's Web site and purchase insurance online.

Property owners can already visit the program's Web site, www.dep.state.pa.us/dep/deputate/minres/bmr/msipage/msi_info.htm , to get information on rates, and view county maps that show where deep mining has occurred.