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3.0 SEISMIC HAZARD DATA FOR EUGENE <br /> <br />Seismic hazard data from the USGS are summarized in Chapter 4 of the <br />Technical Appendix. The seismic hazard curve, showing the annual probability <br />of seismic ground motions is reproduced below. In this figure, the annual <br />probability is on the vertical axis and the level of ground shaking, expressed as <br />peak ground acceleration (PGA, in percent of "g" the acceleration of gravity) is on <br />the horizontal axis. These USGS seismic hazard data are 1996 data, using the <br />same USGS database as the FEMA Seismic Hazard Calculator. However, these <br />data use the full USGS (unpublished) seismic hazard data and thus are more <br />accurate (but completely compatible with) the three data points available on the <br />USGS website as used in the FEMA Seismic Hazard Calculator. <br /> <br /> Figure 1 <br /> Seismic Hazard Curve for Eugene <br /> <br /> 01 <br /> <br /> 001 <br /> <br /> 0004 <br /> <br /> OODO001 <br /> <br /> 00(I)00001 .................... <br /> 00 05 10 t5 20 25 <br /> Peak ~l'ouad ~ccelerat(:n - O <br /> <br /> The seismic hazard curve above represents the cumulative probabilities of <br /> ground motions from all possible earthquake sources. The three main <br /> earthquake sources are: <br /> 1) large earthquakes on the Cascadia subduction zone off the Oregon <br /> coast (interpolate earthquake on the boundary between the subducting <br /> plate and the North American plate) <br /> 2) large earthquakes within the subducting plate (intraplate earthquake), <br /> and <br /> 3) moderate earthquakes within the continental crust near Eugene. <br /> <br /> For purposes of benefit-cost analysis, the seismic hazard data used to generate <br /> the figure above were interpolated to determine the annual probabilities of <br /> various levels of ground shaking (in PGA), as used in the FEMA benefit-cost <br /> <br /> <br />