2011.
This report presents two maps showing historic seismicity in Virginia and North Carolina.
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| Figure 1. Source: http://www.geology.enr.state.nc.us/haz/quake.htm |
Figure 1 is a map of earthquake epicenters recorded in North Carolina and portions of adjacent states between 1698 and 1997. Epicenters are shown only for labeled states. Major geologic provinces and known major faults exposed at the surface are shown for North Carolina. Faults identified to date in North Carolina are ancient and inactive. The lack of correspondence between the locations of earthquake epicenters and these faults indicates they are not responsible for earthquakes in North Carolina within historical times. The faults beneath the surface that generate earthquakes have yet to be positively identified.
Earthquake data before 1886 are sparse. Seismic instruments were installed in the region in the late 1920’s. Prior to that time earthquake data are based on historical records. The distribution of seismograph stations did not allow for location of earthquakes with magnitudes <4 until 1962-1963. Micro-earthquake networks began operating in the region in the mid-1970’s.
Below is recorded earthquakes by the USGS in Virginia from 1990 to present (Figure 2).
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| Figure 2. Source: http://neic.usgs.gov/neis/bulletin/neic_c0005ild_h.html |
