Green Jersey

Rutgers professor: More earthquakes to come

Green Jersey asked Alexander Gates, chair of the Rutgers-Newark Department of Earth and Environmental Sciences, about the earthquakes that rattled nerves in Morris County Feb. 2 (magnitude 3.0) and Saturday (magnitude 2.2). The geology professor told us why quakes happen here, and said there will be more to come.

Green Jersey: Could you tell me a little about what caused the quakes?

Alexander Gates: There were two earthquakes 13 days apart. There is stress on the rocks most likely because of plate tectonic interactions far away from New Jersey. There are numerous small faults in the area that can produce earthquakes when the stress builds up. Once one fault slips, more stress builds up on the nearby faults as a result and they can slip as well.

GJ: Where exactly is the fault line in that area?

AG: It appears that the earthquakes were on two nearby but separate faults. These faults lie east to west across that part of Morris County.

GJ: What other parts of New Jersey are especially prone to this kind of noticeable seismic activity?

AG: The New Jersey Highlands region appears most prone to small earthquakes. This is because the rock is crystalline and very rigid/brittle. It does not bend, but cracks when stressed.

There are earthquakes all over New Jersey. The largest recent earthquake was in 1884 in New York Harbor near Sandy Hook. It had a magnitude of 5.5 and knocked down steeples and pulled houses off of their foundations in Rahway. In 1895, there was a magnitude 4.5 quake in Perth Amboy along the same fault.

A recent study predicts that we could have a magnitude 7 earthquake every 3,400 years in the area. How far along the 3,400 years we are was not mentioned.

GJ: Do you think Morris (or another part of New Jersey) could see another quake in the near future?

AG: We get about two to three earthquakes per year on average in New Jersey, sometimes more. We will definitely get others and Morris County will see them as well.

GJ: Do environmental or human factors impact the frequency or strength of quakes?

AG: Not really.