An unusual earthquake swarm has struck New Jersey, with a series of 6 earthquakes striking in the town of Randolph near Morris Plains and Mendham, west of Morristown and Newark, and east of Flanders and Chester. Ranging from a magnitude of 0.7 to 2.0, all of the earthquakes have been weak but noticeable with dozens of people reporting to USGS they have felt the earthquake. Some have taken to social media to express concern that something larger may be looming.
According to USGS, the first earthquake struck 5:40 am as a weak magnitude 1.6 event which struck from a depth of 5 km. Located just southwest of Parsippany and Paterson and due west of Newark Liberty International Airport, this and the earthquakes that follow it don’t appear to be related to the ongoing earthquake sequence that began in April 2024 further west.
The second earthquake struck at 2:26 pm in the afternoon from a depth of 5km. It was a magnitude 1.3 event, weaker than the first.
The third earthquake struck at 5:51 pm at the same depth; the magnitude was even weaker at 0.7.
The fourth earthquake, also striking from a depth of 5km, struck at 8:19 pm; it was stronger and rated a magnitude 1.2 event.
The fifth earthquake of the series is now the strongest; the magnitude 2.1 event struck at the same depth as the others at 9:00 pm.
The sixth earthquake struck at 11:25 pm and was a bit weaker at 1.1. Like the others, it struck 5 km deep.
According to USGS, earthquakes with a magnitude of 2.0 or less are rarely felt or heard by people, but once they exceed 2.0 , more and more people can feel them. While damage is possible with magnitude 3.0 events or greater, significant damage and casualties usually don’t occur until the magnitude of a seismic event rises to a 5.5 or greater rated event.
Because of the nature of the soil and rock in the area these earthquakes are striking, they seem more noticeable and louder than if they struck in other parts of the country like California.
Morris County Office of Emergency Management told reporters they fielded numerous calls into 911 from residents inquiring about the earthquake activity. Others to took social media to express concern. Dozens also used the “Did you feel it?” website reporting tool that USGS has to report exactly what they felt and when.
USGS is tracking this swarm and says it is unrelated to the dramatic New Jersey earthquake sequence which began with a 4.8 magnitude event on Friday, April 5, 2024 and produced dozens of noticeable earthquakes in just the first week. There were a total of 53 earthquakes measured from April 5 through to April 12 with hundreds since.
Beyond the magnitude 4.8 earthquake, there were moderate aftershocks too. According to USGS, 3.7 magnitude event struck near Bedminster just before 6 pm on April 5, with 10 other earthquakes measuring as a 2.0 or greater magnitude event.
Beyond rattling nerves, the earthquake also damaged the contents of homes and businesses. In Berkeley Heights, Union County, New Jersey, the Berkeley Heights Fire Department reported that the foundation of a home there failed and that the primary earthquake on April 5 was a contributing factor. A Brooklyn middle school gym was deemed unsafe after a Department of Buildings inspection found cracks inside; the rest of the school at 370 Fountain Avenue was determined to be safe. Dozens of gas and water leaks were reported in the region, leaving people without utilities like power or water.
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.
