Acceptable losses? The relative impacts of natural hazards in the United States, 1980–2009

Local and regional hazard management initiatives undertake loss and impact studies to prioritize funds for future mitigation programs. However, hazard loss records typically include only direct damages to property and crops. More flexible measures of hazard losses and impacts are needed to allow comparisons across local places and different time frames, as one mechanism for prioritizing disaster aid and mitigation resources. This study introduces a relative loss ratio at the county level for the US. All losses from geophysical, meteorological, and hydrologic hazards are collected for the period 1980–2009. The loss data are normalized by a measure of economic capacity calculated using county and state employment data and state Gross Domestic Product estimates. A statistical regionalization technique is utilized to identify hazard regions of the US which consistently suffered heavy losses in comparison to their economic capacities. For the nation, the average relative loss ratio is 0.15% of the US GDP, suggesting that overall relative impact of disasters has not been that large. However, downscaling to regional or county levels shows a different result with the relative impact exceeding 10% of county GDP for many places, and more than 3% of regional GDP in the central US and the Gulf Coast. While the national capacity to absorb and recover from disasters is quite high, local capacities are often exceeded by singular large events or the cumulative impacts of smaller events, necessitating the influx of external aid to help these places recover from hazards.