In the aftermath of the earthquake in New Jersey that shook the entire tri-state area and beyond, more than a dozen aftershocks were reported in the ensuing hours in the region — including a 4.0-magnitude quake early Friday evening, according to the USGS.
The epicenter of that aftershock just before 6 p.m. was said to be 7.4 miles northwest of Bridgewater, which is just over the county line in Somerset County. It was very close to the site of the initial quake near Whitehouse Station, just south of Tewksbury in Hunterdon County, about 40 miles west of New York City, at 10:23 a.m.
The aftershock was significantly deeper than the initial quake, about 5.6 miles deep, which explains why it wouldn't have been felt by as many people.
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A much smaller aftershock, magnitude 2.0, was reported by the USGS in Bedminster, New Jersey, around 11:20 a.m. It was one of 12 aftershocks since the initial quake that have registered at least 1.8 or higher on the Richter scale, according to USGS geophysicist Timothy Clements. There may have been more, but any below 1.8 in magnitude would have been undetected.
So how long can the area expect to possibly feel additional aftershocks? The chance will still around for at least some time, experts say.
Further aftershocks will be unpredictable but are possible for the next week, experts say. The USGS said there would be nearly a 50% probability of an aftershock magnitude 3.0 or more, a 16% of one magnitude 4.0 or more, and even a 3% chance of one that was more intense than the initial quake.
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If you find yourself in an aftershock, experts say you should drop to the floor and cover your neck.
