New York City is seismically active, even though it is not situated on a major tectonic plate boundary. The city lies within an intraplate environment, far from the edges of the North American Plate where most large earthquakes occur. Shaking is infrequent and typically minor, yet the potential for a larger, damaging event exists. While the probability of a major event is low, the metropolitan area has a measurable seismic risk due to its dense population and built environment.
History of Seismic Activity in the NYC Region
The history of the New York City region includes records of notable earthquakes. The most significant historical event was the magnitude 5.0 to 5.2 earthquake in August 1884, likely centered near Brooklyn or Long Island. This tremor caused minor damage across the city and surrounding areas, including fallen bricks, cracked plaster, and broken windows in nearby New Jersey and Connecticut.
Residents have also felt the effects of distant, larger quakes, demonstrating the ability of East Coast geology to transmit seismic energy efficiently over great distances. A notable instance occurred in August 2011, when a magnitude 5.8 earthquake centered in Virginia caused buildings in Manhattan to sway, prompting some evacuations. A magnitude 4.8 earthquake centered in New Jersey in April 2024 also rattled the city, causing widespread shaking but no major structural damage.
The Underlying Geology of Northeast Earthquakes
Earthquakes in the Northeast are driven by the massive stress field generated by the slow, constant westward movement of the North American Plate. This movement causes strain to build up across the stable continental interior, resulting in seismicity within the interior of the tectonic plate.
The accumulated strain is released along ancient zones of weakness buried deep within the crust. These are pre-existing fractures that originated hundreds of millions of years ago when the continent was actively rifting and colliding. When the current regional stress exceeds the strength of these old faults, they can be reactivated, resulting in an earthquake. Since the deep faults are not always clearly visible on the surface, predicting the exact location and timing of these tremors remains a challenge for seismologists.
Assessing Current Seismic Risk
The United States Geological Survey (USGS) includes the New York City region in its national seismic hazard assessment, acknowledging the potential for a moderate earthquake (magnitude 5.5 to 6.0). While the probability of such an event is low, perhaps occurring only once every century or more for a magnitude 5 or greater, the consequences in a dense urban area are significant. The primary risk comes from the vulnerability of the city’s vast inventory of older structures. Most buildings were constructed before 1995, when modern seismic design provisions were first adopted into the city’s building codes.
Unreinforced masonry buildings, particularly low-rise brick structures common in boroughs like Brooklyn and Queens, are highly susceptible to damage during strong shaking. Masonry lacks the flexibility and steel reinforcement needed to absorb forces, leading to a risk of collapse or severe non-structural damage. Furthermore, areas built on artificial fill or soft soil, which can be found across the city, are prone to amplified ground shaking and the risk of soil liquefaction, which destabilizes foundations.
Newer high-rise buildings are generally more resilient, having been designed with flexibility to withstand high wind loads and meeting stringent post-1995 seismic codes. The city’s preparedness planning includes design requirements for a Maximum Considered Earthquake, a rare but possible event that would cause strong shaking. Ongoing risk mitigation efforts focus on strengthening infrastructure and improving public awareness.