Aftershocks continue rattling New Jersey residents after rare 4.8 quake

April 6 (UPI) -- Dozens of aftershocks continued shaking New Jersey residents on Saturday following the previous day's rare 4.8 magnitude earthquake centered in the Garden State's Readington Township.

Seismologists with the U.S. Geological Survey have recorded 31 aftershocks ranging from 1.5 to 4.0 and have warned they will continue for about a week following the strongest earthquake to hit the northeastern United States in a century.

The 4.0 aftershock occurred at 5:59 p.m. EDT Friday near Gladstone in New Jersey's Somerset County.

More aftershocks were recorded in Hunterdon, Somerset and Morris counties, according to the USGS.

Aftershocks generally are a concern for up to a week after an earthquake, Queens College seismologist and assistant professor Dax Soule told CBS News.

"The entire East Coast is a seismically active area," Soule said. "But most of the earthquakes are relatively small."

The USGS said Friday's earthquake was moderate and those ranging from magnitude 2.5 to 5.4 are felt but only cause minor damage. About 500,000 such earthquakes occur every year.

By comparison, the deadly 1994 earthquake centered in Northridge, Calif., was a magnitude 6.7, which the USGS classifies as a strong earthquake. The Northridge event killed 57, injured about 9,000 and caused an estimated $20 billion in damages to more than 112,000 structures.

Friday's earthquake triggered power outages in Newark as well as dozens of gas leaks and caused local officials to inspect three homes before determining they were structurally sound.

The quake also caused a water main break that flooded a street in Randolph, N.J., and a tree to fall and damage a grist mill built in 1760. The grist mill collapsed following Friday morning's earthquake.

The seismic event affected New York City, but officials for the city's Metropolitan Transportation Authority said its subways, bridges and tunnels stayed intact during the earthquake.

The earthquake rattled homes throughout the Tri-State area and into upstate New York.

New York officials are assessing potential damage and will update residents throughout the assessment process, New York Governor Kathy Hochul said.

The USGS said Friday's temblor was moderate and those ranging from magnitude 2.5 to 5.4 are felt but only cause minor damage. About 500,000 such earthquakes occur every year.