A newly discovered fault line in New Jersey is believed to have caused the magnitude 4.8 earthquake that shook much of the Northeast in April 2024, according to a new study.

The earthquake, centered near Tewksbury, was initially believed to be connected to the Ramapo Fault. However, researchers now say evidence points to a previously unidentified fault known as the Mountainville Fault.

The study, published in the Journal of Geophysical Research: Solid Earth, found that the fault dips approximately 45 degrees underground, allowing seismic energy to spread across a wide area. The earthquake was felt from Virginia to Maine, including throughout New Jersey and New York.

Researchers described the Mountainville Fault as an “immature” fault and said the discovery does not necessarily mean another earthquake is imminent. Experts stressed that New Jersey remains a relatively low-risk earthquake region, but identifying previously unknown faults can help scientists better understand future seismic activity.