According to USGS, 35 earthquakes with a magnitude of 1.5 or greater have rattled New Jersey and surrounding areas, with 34 of them coming after a strong 4.8 magnitude event hit Tewksbury. USGS is describing these earthquakes after the primary one as “aftershocks”; however, aftershocks and foreshocks are earthquakes too. USGS has also updated their aftershock forecast, outlining how many more earthquakes are likely to hit the Garden State in the coming hours, days, and weeks.
At 10:23 am on Friday, the magnitude 4.8 earthquake struck Tewksbury Township near Lebanon and Whitehouse Station from a depth of 4.7 km. The earthquake was strong enough for the National Tsunami Warning Center in Palmer, Alaska to issue a tsunami bulletin about it, advising people there was no threat of tsunami along the Jersey Shore, New York City, the waters around Long Island, or beyond. There were numerous reports of light damage coming in from New Jersey.
More than 100,000 people used the USGS “Did you feel it?” form on their website to report they felt shaking. Because of its magnitude and depth, and due to the rocky make-up of the terrain in the area in which it struck, the earthquake was felt south into the Mid Atlantic and north into New England, with thousands of reports coming in from Baltimore, Maryland and Hartford, Connecticut and points in between.
Of the 32 aftershocks, a strong 4.0 magnitude event was one of them and was felt across the area when it struck at 5:59 pm Friday evening. Most of those other earthquakes were a magnitude 2.5 or less and were only felt in the area immediately around the primary earthquake.
Most of the epicenters have been on local roads or properties. One earthquake epicenter struck under the clubhouse at Trump National Golf Club in Bedminster. None have been around the Round Valley Reservoir or the earthen dams that hold back the water there.
USGS continues to warn about the prospect of additional earthquakes in New Jersey, saying that damaging earthquakes can occur in the future; they remind people to remember to “Drop, Cover, and Hold on” should a quake occur. More earthquakes than usual, called aftershocks, will continue to occur near the mainshock. The mainshock is the largest earthquake in a sequence which is a series of earthquakes related to each other. When there are more earthquakes, the chance of a large earthquake is greater which means that the chance of damage is greater. But USGS adds, “No one can predict the exact time or place of any earthquake, including aftershocks. Our aftershock forecasts give us an understanding of the chances of having more earthquakes within a given time period in the affected area.”
Based on the latest USGS aftershock for the next 30 days, they believe it is likely more earthquakes will continue to strike New Jersey. In the latest forecast, USGS says there’s an 80% chance that a magnitude 3.0 or greater earthquake will strike; there is a 16% that a magnitude 4.0 or greater will strike, and only 2% that a magnitude 5.0 or greater will strike. The chance of a magnitude 6, 7, or even greater event is less than 1%.
