SECTION 4: RISK ASSESSMENT
depicted in USGS earthquake hazard maps by showing, by contour values, the earthquake ground motions (of a particular frequency) that have a common given probability of being exceeded in 50 years. Figure 4.15 reflects the seismic hazard for Wake County based on the national USGS map of peak acceleration with two percent probability of exceedance in 50 years. To produce these estimates, the ground motions being considered at a given location are those from all future possible earthquake magnitudes at all possible distances from that location. The ground motion coming from a particular magnitude and distance is assigned an annual probability equal to the annual probability of occurrence of the causative magnitude and distance. The method assumes a reasonable future catalog of earthquakes, based upon historical earthquake locations and geological information on the recurrence rate of fault ruptures. When all the possible earthquakes and magnitudes have been considered, a ground motion value is determined such that the annual rate of its being exceeded has a certain value. Therefore, for the given probability of exceedance, two percent, the locations shaken more frequently will have larger ground motions. Wake County is located within the light blue and dark gray zones representing a low peak acceleration of 0.04 to 0.1% g. Figure 4.15 – Seismic Hazard Information for North Carolina
Source: USGS Earthquake Hazards Program
Based on this data, it can be reasonably assumed that an earthquake event affecting Wake County is unlikely.
Probability: 1 – Unlikely CLIMATE CHANGE
Scientists are beginning to believe there may be a connection between climate change and earthquakes. Changing ice caps and sea-level redistribute weight over fault lines, which could potentially have an
Wake County, NC Multi-Jurisdictional Hazard Mitigation Plan
WSP June 2024 Page 112
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