A recent earthquake in New Jersey displayed unusual seismic activity and shaking patterns, impacting areas much farther than expected. Research indicates it happened on an unmapped fault, challenging existing models of earthquake risk in the region.

On April 5th, 2024, a magnitude 4.8 earthquake struck northern New Jersey’s Tewksbury township, triggering widespread alarm. Although the region occasionally experiences small tremors, this was the largest since 1884, when an earthquake of approximately magnitude 5 struck under the seabed off Brooklyn.

According to existing models, the earthquake should have caused substantial damage at its epicenter, yet it remained largely unscathed. In contrast, relatively distant New York City shook much harder than expected, resulting in minor damages. Outsize shaking extended all the way to Virginia and Maine. A recent study suggests why this happened, challenging existing assumptions about regional earthquake hazards.

While 4.8 is not a major quake in global terms, people in the highly populous U.S. Northeast are not used to anything that big. The U.S. Geological Survey (USGS) estimates it was felt by some 42 million people; a USGS online portal that crowd-sources first-person reports of shaking received nearly 184,000 entries―the most ever from any U.S. quake, according to a companion paper about the event. Both papers were recently published in the journal The Seismic Record.