Experts explained why earthquakes in New York City are unusual because the closest plate boundaries to the area are located in the center of the Atlantic Ocean and in the Caribbean Sea.
Plate Subduction Zones
Based on previous study, the northeastern portion of the United States does not have tectonic plate subduction zones like those by California and the Pacific Northwest. These are places where a thinner plate dips beneath an adjacent, thicker one.
Officials said that the faults are left over from ancient mountain building events, including the rise of the Appalachian mountains.
They noted that when the supercontinent Pangaea arose and broke up, it was able to leave deep fractures and faults in the bedrock that can reactivate for various reasons, such as the crust readjusting to changes.
Many smaller or deeper faults in the New York, Philadelphia and Wilmington urban corridor likely remain undetected, authorities noted, with most of the region's small earthquakes cannot be linked to a named fault.
Moreover, it is difficult to determine if a known fault is still active and could slip and cause an earthquake.
The United States Geological Survey (USGS) said that the magnitude 4.8 earthquake near Whitehouse Station, New Jersey, occurred as a result of oblique reverse and strike-slip faulting at shallow depths in the crust.
Experts pointed out that although this event did not occur near a plate boundary, such "intraplate" earthquakes can and will still occur.
While this earthquake is relatively small globally, earthquakes of this magnitude are commonly widely felt in the eastern US due to the efficient seismic wave propagation in the region.
Earthquakes in the eastern US are infrequent but not unexpected. Since 1950, 40 other earthquakes of magnitude 3 and larger have occurred within 250 km of today's earthquake.
During that time range, the said earthquake was the largest. Within 500 km of the April 5th earthquake, 13 earthquakes of magnitude 4.5 and larger have been recorded since 1950, the largest being August 23, 2011.
Meanwhile, the magnitude 5.8 Mineral Virginia earthquake had caused substantial damage and was felt throughout the eastern US.
Little To No Damage
The April 5, 2024 earthquake occurred in a region where faults have been previously identified and may be reactivated at any time.
In New Jersey, Governor Phil Murphy said there are limited reports of damage and "little to no injuries" in the state. The USGS recorded at least six aftershocks in the immediate area of the initial earthquake.
Meanwhile, New York Governor Kathy Hochul said there were no "life-threatening situations" after the earthquake and no reports of damaged buildings. There was one report of a gas line leak, but so far there's no "major" infrastructure impact, state officials said.
Authorities said that the tremors were felt by millions of people across hundreds of miles of the Northeast, a phenomenon made more likely by a few factors including the geology of the region itself.
Rocks in the eastern US are much older, denser and harder, making them more efficient conduits of the seismic energy released by an earthquake.
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