How Safe Are New York Buildings From Earthquakes?
New York City’s buildings are fine after a 4.8 magnitude earthquake on Friday, but they aren’t all created equally, according to Troy Morgan, an adjunct professor at Columbia University’s civil engineering department.
Even though earthquakes like Friday’s 4.8-magnitude tremor are rare in the Northeast, they cause damage to buildings that aren’t properly reinforced. Authorities across New York and New Jersey, where the quake started, said they have found virtually no damage to infrastructure, although several homes in Newark were evacuated because they were deemed unstable.
Structural engineer Troy Morgan, an adjunct professor at Columbia University’s civil-engineering department, has designed bridges and buildings nationwide that withstand earthquakes and is currently doing investigative work to determine when damage occurs to a structure and why it occurred. (He was skiing in Utah when the quake hit.) He believes New Yorkers shouldn’t worry but acknowledges that not every building in the city is prepared to withstand a stronger earthquake.
The U.S. Geological Survey located this outside of Plainfield, New Jersey. Is there a fault line near there?
It’s not necessarily a major fault line. Earthquakes could happen in the middle of plates, just because there are fractures in the crust. It’s not a fault line per se.
When was the last time this happened?
In Queens, there was an earthquake detected by sensors within the last six months. But the biggest earthquake was the 5.8-magnitude one in Virginia that happened 13 years ago.
Which city buildings are the least equipped for an earthquake?
Generally, unreinforced masonry or brick buildings because they’re heavy and they lack steel reinforcement. Things that are heavy experience more force, and if they don’t have enough steel reinforcement to resist those forces, they can be susceptible to damage. There are a lot of brick buildings in New York, New Jersey, and Connecticut, and those are buildings you’d expect to see cracking to develop or damage to their foundations. You can get shaking if there’s a large enough quake, and you can get liquefaction, where the soil temporarily liquifies, and you can get settlement that results from that.
How serious is a 4.8-magnitude earthquake compared with what California regularly experiences?
So 4.8 is not very large. The intensity of shaking relates to the magnitude of the earthquake as well as the distance. A 4.8-magnitude that happens 100 miles away is less severe and there’s less damage potentially compared with one that occurs ten miles away. As an earthquake, 4.8 is not that large in terms of damage potential for buildings, but if buildings aren’t well designed, there could be damage.
Also, an aftershock would be an order of magnitude lower than the earthquake. So if 4.8 is the main shock, you’d expect 3.8 or less for aftershocks.
What do we say to Californians that will make fun of us for overreacting?
I don’t think it’s an overreaction, honestly. If an area does not experience earthquakes often, it can be scary. Any shaking can be terrifying. It is honestly news that an earthquake happened in the Northeast. People should be aware that ground shaking in the Northeast can happen and can be damaging. So this one may not have caused damage, but it should create some awareness that the earth can shake in New York. But buildings are designed for earthquakes.
What advice would you give New Yorkers for dealing with this in the future?
There really is no practical way to get notice of an earthquake happening. There’s no way to detect an earthquake before it actually occurs.
I would just say that earthquakes are a reality of the Northeast United States. They don’t happen often, they’re not really large. Our buildings and infrastructure are designed for earthquakes. I don’t think they should be concerned that an earthquake of this magnitude results in damage. It can happen, but it’s rare. Being prepared is something people should keep in mind, but I don’t think it should be a major concern.