New Jersey saw its 145th earthquake of the month today, including a strong aftershock which struck earlier today and generated nearly a thousand reports of shaking from across the Garden State to the USGS. An earthquake sequence began in northern New Jersey on the morning of April 5, with a magnitude 4.8 earthquake striking near Tewksbury at 10:23 am. Since then, there have been 144 additional aftershocks, including two stronger ones; a magnitude 3.7 struck on the evening of the first quake and today, a magnitude 2.9 earthquake struck in nearly the same place at 9:49 am.
Today’s earthquake struck from a depth of 8.5 km. According to USGS, nearly a thousand people reported they felt shaking across parts of New Jersey from the morning aftershock. Within the 959 reports that USGS received via the “Did you feel it?” reporting tool on their website, people as far south as Hamilton, New Jersey, as far west as Allentown, Pennsylvania, as far north as White Plains, New York, and as far east as western Long Island experienced today’s latest earthquake.
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.
USGS says there is still a slight chance of more aftershocks over the next 30 days. In their latest aftershock forecast, they report there is a 33% chance that a magnitude 3.0 or greater earthquake will hit again; those odds drop down to 4% for a magnitude 4.0 or greater event. While low, these odds have increased over the last 2 weeks due to the persistent seismic activity happening here.
According to USGS, the April 5, 2024 occurred as a result of oblique reverse and strike-slip faulting at shallow depths in the crust. Although this event did not occur near a plate boundary, such “intraplate” earthquakes can and do occur. “While this earthquake is relatively small globally, earthquakes of this magnitude are commonly widely felt in the eastern United States because of efficient seismic wave propagation in the region,” the USGS said.
Earthquakes in the eastern US are infrequent but not unexpected. Since 1950, 40 other earthquakes of magnitude 3 and larger have occurred within 155 miles of the April 5 earthquake. In that time range, the April 5, 2024, earthquake is the largest. Within 310 miles of the April 5th earthquake, 13 earthquakes of a magnitude 4.5 and larger have been recorded since 1950, the largest being the August 23, 2011, the magnitude 5.8 Mineral, Virginia earthquake which caused substantial damage and was felt throughout the eastern US. The April 5, 2024, earthquake occurred in a region where faults have been previously identified and may be reactivated at any time.