A 4.8 magnitude earthquake struck the northeastern at 10:23 a.m. Friday, according to the United States Geological Survey (U.S.G.S.), sending tremors from Philadelphia to Boston and shaking buildings in Manhattan and the five districts of New York City.
The U.S.G.S. reported that the earthquake’s epicenter was in Lebanon, New Jersey, about 50 miles west of New York City.
The New York Police Department said it had no immediate reports of damage, but sirens could be heard throughout the city. Several East Coast airports halted air traffic immediately after the quake.
One of the biggest earthquakes in 50 years
The 4.8 magnitude earthquake was the third largest earthquake recorded in the northeastern region of the United States in the last 50 years, according to data from the U.S. Geological Survey.
The largest earthquake, magnitude 5.3, occurred in Au Sable Forks, New York, in 2002.
Is the region prone to tremors?
Earthquakes are rare in the northeast because the phenomenon happens more frequently and intensely in regions where tectonic plates meet.
Tectonic plates are large semi-rigid rock blocks that make up the Earth’s crust. The Earth is divided into fourteen main tectonic plates, which move over the mantle slowly and continuously, and can move closer or further away from each other. The movement of these plates results in the formation of mountains, ocean trenches, volcanic activities, earthquakes, and tsunamis.
The northeastern region of the United States is not where tectonic plates meet, but rather in the center of the North American Plate. Therefore, earthquakes are not common in the region.
However, the area is not free of them. Friday’s earthquake occurred on the Ramapo fault system, which runs through the northern Appalachian Mountains in New York, New Jersey, and Pennsylvania. Faults are lines of fractures between two blocks of rock in the Earth’s crust, the geological layer closest to the surface. Movements in these fractures cause tremors, like those felt on Friday morning.
In 2008, researchers at Columbia University analyzed 383 earthquakes in a 15,000-square-mile area around New York City and estimated that a magnitude 5 earthquake in or around the city occurs on average once a century, while a magnitude 5 earthquake of magnitude 6 or greater occurs once every 670 years. An even greater magnitude – 7 is estimated once every 3,400 years.
The historical record has included three earthquakes of magnitude 5 or greater, the most recent in 1884, which is 140 years ago.
The risks of an earthquake in New York
Although earthquakes in the northeastern United States are smaller and less frequent than in places like California or Japan, the risks deserve attention from authorities.
A modest earthquake, like Friday’s, could cause millions of dollars in damage to cities like Manhattan. This is because the region is not prepared for them.
In the early 2000s, New York City began requiring building designers to take seismic risks into consideration. Before that, the main natural hazard that the city’s building code covered was wind, which can put a lot of pressure on buildings, especially skyscrapers. However, the vast majority of the 1.1 million buildings in New York City were built before 2000 and therefore were not designed with earthquakes in mind.
Even though it scared those who are not used to tremors, Friday’s earthquake, at first, did not cause damage to the infrastructure of the large cities that make up the region and did not leave any victims in one of the most populous areas of the country.
Source: The New York Times and CNN