GEOLOGIC HAZARDS IN PENNSYLVANIA: ECONOMIC AND SOCIAL COSTS AND NEW TOOLS FOR MAPPING

Mapping and research to identify and understand geologic hazards is a key factor in mitigation efforts, but financial support and political will to apply the information gathered is also needed. Complete and accurate information on the economic and social costs of hazards would help to convince decision makers of the importance of the hazards, but is difficult to compile. Reasons include proprietary, legal and privacy concerns; lack of reporting standards and follow-up; and difficulty identifying indirect and accessory costs. Documented partial costs suggest that total costs of landslides in Pennsylvania are in the tens of millions of dollars per year on average. Inclusion of indirect costs such as lost work and increased travel time would increase the total.

A major landslide near Pittsburgh in 2006 generated legislative interest in geologic hazards in Pennsylvania, but proposed legislation mandating statewide mapping and state review of large development projects was not enacted when first introduced.

The next steps in the Pennsylvania Geological Survey's ongoing hazards work will likely be conversion of historic paper records on landslides to a digital database as has already been done for sinkholes. Lidar elevation data from the PAMAP program in 2006 and 2007 has shown preliminary promise for identification of landslide and sinkhole occurrences, and Pennsylvania now has coverage of approximately the western 2/3 of the state with lidar data and derived 2-foot contours and 3.2-foot grid DEM. Comparisons with older mapping suggest that lidar greatly enhances identification of features in forested areas, and provides increased detail everywhere. Historical aerial photos will remain important for areas where land-use changes and other modifications have obscured subtle features.