Seismic Hazard Estimation in the Eastern U.S.

Probable seismic hazard is generally estimated considering five elements: 1) seismicity; 2) source radiation; 3) wave propagation (attenuation); 4) site response; and 5) ground failure. These elements are reviewed for the Eastern US by comparing new data with prior expectations based mostly on 'expert opinion', sparse data, and extrapolations from west-coast experiences. Results are often sobering: data and prior can differ by an order of magnitude. The large variances suggest: 1) expect future 'surprises'; 2) assess propagation of uncertainties; 3) state the confidence interval above the mean at which one maps hazards parameters for code applications. Low percentiles invite eventual losses, high percentiles raise mitigation costs. Cost estimates for future eastern losses and preventive measures surprise an increasingly informed, but mostly unprotected urban populace which, by chance, has been spared for decades from life-threatening direct hits in the Eastern US.