It was a seismically active day today in the East Coast, where three weak earthquakes struck. Earthquakes in New Jersey, South Carolina, and North Carolina were measured by USGS but were too weak to generate reports into their “Did you feel it?” website reporting tool; nor were any damage or injuries reported.
The first of the three earthquakes struck northern New Jersey at 2:41 am near Lebanon. This was likely an aftershock from a magnitude 4.8 earthquake which struck on April 5 near today’s epicenter. More than 100,000 people used the USGS “Did you feel it?” reporting tool to report shaking from that initial quake. Because of its magnitude and depth, and due to the rocky make-up of the terrain in the area in which it struck, the earthquake was felt south into the Mid Atlantic and north into New England, with thousands of reports coming in from Baltimore, Maryland and Hartford, Connecticut and points in between. But because today’s event struck at a depth of 5 km and was only a magnitude 1.3, it would be unlikely most people would notice it –especially due to the hour it struck.
The second earthquake struck near Coronaca, South Carolina, where an unusual earthquake swarm started just days ago. On Sunday alone, 8 earthquakes struck this area, generating several “Did you feel it?” reports to the USGS. Today’s earthquake, a magnitude 1.5 event, struck from a depth of 4 km at 7:13 am. Today’s epicenter was in the middle of the apparently ongoing swarm, located near the south shore of Lake Greenwood; the area was hit hard by recent heavy rain and strong wind from Hurricane Helene.
According to USGS, a swarm is a sequence of mostly small earthquakes with no identifiable mainshock. “Swarms are usually short-lived, but they can continue for days, weeks, or sometimes even months,” USGS adds.
The third earthquake struck in southwestern North Carolina near the state lines with Georgia and South Carolina. With an epicenter near Rosman, North Carolina, the magnitude 1.5 event here struck at 12:27 pm from a depth of 6.9 km. This is an area that has seen no nearby seismic activity over the last three weeks according to USGS.
The eastern United States does see earthquakes from time to time. According to USGS, there’s been a total of 28 earthquakes over the last 30 days from the Appalachian Mountains to central Maine. South Carolina and New Jersey have had the most earthquakes over that period.
