Northeast Pennsylvanians have empathy for Floridians regarding the sinkholes that suddenly open in that state, sometimes swallowing buildings and streets.

The most common cause of the Florida sinkholes appears to be the erosion of subterranean limestone by water than has grown more acidic in recent years.

In the anthracite region, the cause of frequent subsidence is more directly man-made - the collapse of mine voids.

In Pennsylvania, subsidence should not be a surprise because the mines were supposed to have been meticulously mapped, and mine operators were supposed to ensure that enough coal was left in pillars to support the surface.

But mines weren't always mapped accurately, and even when they were, unscrupulous operators sometimes "robbed the pillars" as a mine played out, removing coal that was supposed to be left to support the ground above.

Finally, more than half a century after the demise of most of the anthracite industry, a project is under way to develop more accurate mine maps. Using a $321,000 grant from the Department of Environmental Protection Mine Subsidence Insurance Board, the Eastern Pennsylvania Coalition for Abandoned Mine Reclamation has undertaken the effort. Rather than relying on old maps alone, the project involves on-site visits and measurements to verify and correct existing data.

The project is a sound, long overdue effort that could better protect existing property and help promote economic development.