SECTION 4: RISK ASSESSMENT
According to data from the USGS Earthquake Hazards Program, there has been a total of 13 recorded earthquakes with a magnitude of 2.5 or greater that have occurred within 100 miles of Wake County from 1973 to 2023. Approximately 69% of these earthquakes were measured with a magnitude between 2.5-3.0 on the Richter scale, while 31% were measured with a magnitude between 3.0-4.0. The highest recorded magnitude of these earthquakes was 3.8, which occurred twice, in 1994 and in 1998. The most recent earthquake to occur within 100 miles of Wake County was on November 15 th , 2015, located in Denton, North Carolina, and had a magnitude of 2.6. The above map documents all earthquakes that have occurred within North Carolina; however, given the long distances across which earthquake impacts can be felt, these events do not encompass all earthquakes that have affected North Carolina. The following data, detailed in Table 4.27, was compiled and presented in the 2019 Wake County Hazard Mitigation Plan and remains relevant to the planning area. Table 4.27 – Historical Earthquakes Impacting North Carolina
Richter Scale (Magnitude)
MMI (Intensity)
MMI in North Carolina
Date
Location
12/16/1811 – 1 12/16/1811 – 2 12/18/1811 – 3 01/23/1812 02/071812 04/29/1852 08/31/1861 12/23/1875 08/31/1886 05/31/1897 01/01/1913 02/21/1916 07/08/1926 11/03/1928 05/13/1957 07/02/1957 11/24/1957 10/27/1959 * 07/13/1971 11/30/1973 11/13/1976 05/05/1981
NE Arkansas NE Arkansas NE Arkansas
8.5 8.0 8.0 8.4 8.7 5.0
XI
VI VI VI VI VI VI
X X
New Madrid, MO New Madrid, MO Wytheville, VA Wilkesboro, NC Central Virginia Charleston, SC Giles County, VA Union County, SC
XI
XII
VI
5.1
VII VII
VII
5.0 7.3 5.8 4.8 5.5 5.2 4.5 4.1 3.7 4.0 4.0 3.8 4.6
VI
X
VII
VIII
VI VI
VII VII VII
Asheville, NC
VII VII
Mitchell County, NC
Newport, TN
VI VI VI VI VI VI VI VI VI
VI VI VI VI VI VI VI VI VI
McDowell County, NC Buncombe County, NC Jackson County, NC
Chesterfield, SC
Newry, SC Alcoa, TN
Southwest Virginia
4.1
Henderson County, NC
3.5
* Conflicting reports on this event, intensity in North Carolina could have been either V or VI Source: 2019 Wake County Hazard Mitigation Plan (This information compiled by Dr. Kenneth B. Taylor and provided by Tiawana Ramsey of NCEM. Information was compiled from the National Earthquake Center, Earthquakes of the US by Carl von Hake (1983), and a compilation of newspaper reports in the Eastern Tennessee Seismic Zone compiled by Arch Johnston, CERI, Memphis State University (1983)). PROBABILITY OF FUTURE OCCURRENCE Ground motion is the movement of the earth’s surface due to earthquakes or explosions. It is produced by waves generated by a sudden slip on a fault or sudden pressure at the explosive source and travels through the earth and along its surface. Ground motion is amplified when surface waves of unconsolidated materials bounce off of or are refracted by adjacent solid bedrock. The probability of ground motion is
Wake County, NC Multi-Jurisdictional Hazard Mitigation Plan
WSP June 2024 Page 111
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