Earthquakes are a consistent, though generally low-level, feature of New York State’s geology. While most tremors go completely unnoticed, the potential for a larger, more damaging event remains a recognized hazard. Understanding why these tremors happen, despite the state being thousands of miles from any major tectonic plate boundary, is the first step toward recognizing this sometimes-overlooked aspect of living in the Northeast.
Confirmation and Historical Context
New York State has recorded over 550 seismic events since the first recorded event in 1737. Most are micro-quakes, registering below magnitude 3 and only detected by scientific instruments. Seismic activity concentrates primarily in three regions: the greater New York City area, the Adirondack Mountains, and the western part of the state near Buffalo and Attica. The most significant earthquake in the New York City metropolitan area occurred on August 10, 1884, estimated at magnitude 5.0 to 5.5. This tremor caused minor damage, such as fallen chimneys and cracked plaster, and was felt from eastern Pennsylvania to central Connecticut.
Major Historical Events
Northern New York experienced the state’s largest recorded earthquake, a magnitude 5.9 event in 1944 near Massena, which caused significant structural damage. More recently, a magnitude 5.3 quake near Au Sable Forks in the Adirondacks in 2002 caused widespread, though minor, damage like broken glass and cracked roads.
The Underlying Geology
New York’s seismic events are classified as intraplate earthquakes because they occur deep within the North American continental plate, far from dynamic plate boundaries. The closest major boundary is the Mid-Atlantic Ridge, located thousands of miles away. These tremors result from slow, continuous stress transmitted across the continent’s stable interior.
Sources of Stress
This stress is a combination of forces, including the ongoing push from the spreading Mid-Atlantic Ridge and residual stress from the removal of massive ice sheets following the last Ice Age. The immense weight of the glaciers depressed the crust, and the subsequent upward rebound, known as post-glacial rebound, continues to contribute to crustal stress. This energy is released along ancient zones of weakness.
Faults and Energy Transmission
The bedrock beneath New York contains numerous pre-existing, buried fault lines—remnants from ancient mountain-building events. These old fracture zones act as weaknesses in the crust. Modern tectonic stress reactivates these faults, finding the path of least resistance. The dense, hard crystalline rock underlying the eastern United States transmits seismic energy much more efficiently than the younger, fractured rock of the West Coast. This means a moderate earthquake in New York can be felt over a much larger geographical area than a similar quake in California.
Assessing the Seismic Hazard
While the probability of a major event is statistically low compared to high-seismicity zones, New York City faces a heightened seismic risk due to its dense population and extensive infrastructure. Experts estimate that a magnitude 5.0 or greater event could occur in the region approximately once every 100 years.
Building Vulnerability
A primary concern is the large number of buildings constructed before 1995, when New York City adopted its first modern seismic design provisions. Structures built before this time, particularly unreinforced masonry buildings, are especially vulnerable to shaking. These structures lack the flexibility to absorb seismic forces, increasing the risk of structural failure during a moderate earthquake.
Preparedness
State agencies maintain continuous monitoring of seismic activity to inform public safety measures. For residents unaccustomed to frequent shaking, basic preparedness focuses on the immediate response to protect against falling objects. The recommended action during an earthquake is to “Drop, Cover, and Hold On”: immediately drop to the floor, take cover underneath a sturdy piece of furniture, and hold onto it until the shaking stops.