Will the shaking continue around Whitehouse Station, NJ in the coming days? Almost certainly.
In fact, several aftershocks have already occurred. The latest, at 5:59 pm Eastern time according to the United States Geological Survey, occurred near Gladstone, NJ, and had an initial magnitude of 4.0 and was reportedly felt throughout the region.
The earlier aftershocks were of magnitude 2.0, almost imperceptible even to people standing right at the epicenter.
Larger aftershocks are also possible.
USGS forecasts a 45 percent chance of an aftershock of magnitude-3 or greater next week. The odds increase to 66 percent the following year.
Is this a prelude to a devastating earthquake? Maybe, but not likely.
Large earthquakes of magnitude-7 or greater are often preceded by moderate foreshocks. But so far, seismologists have not been able to identify any unique characteristics of an earthquake that would warn of an impending larger earthquake.
If there is a devastating earthquake next week, seismologists will call Friday’s tremor a foreshock. But they have no way to confidently predict a major earthquake in advance.
Seismologists also know that large earthquakes are rare in this part of the world. A 2008 study by scientists at the Lamont-Doherty Earth Observatory at Columbia University found that a magnitude-5 earthquake occurs in the New York City region about once a century, a magnitude-6 or larger about once every 670 years and a magnitude-7. once every 3,400 years.
That’s reflected in the geological survey’s aftershock forecast, which currently says there’s less than a 1 percent chance Friday’s quake will be followed by a magnitude-6 earthquake or larger. Even the chance of a comparable earthquake of magnitude 5 is only 3 percent next week and 8 percent next year.
The forecast will be updated as instruments measure new seismic data.
John Keefe contributed reporting.
