Geologist says NJ, NY earthquakes are unusual, notes waves arrived in WV

Newswise — A West Virginia University researcher said the Friday (April 5) 4.8 magnitude earthquake, centered just north of Whitehouse Station, New Jersey and less than 50 miles west of New York City, was an uncommon event.

Thomas Wilson, emeritus professor of geology at the WVU Eberly College of Arts and Sciences, reported the quake’s waves arrived in Morgantown and were recorded on the University’s seismograph within roughly one minute of onset.

Quotes:

“It is pretty unusual to have earthquakes of this magnitude in the New Jersey, New York area. This earthquake occurred at a depth of about 4.7 kilometers, around three miles. The U.S. Geological Survey ShakeMap indicates the intensity, or how the earthquake was felt, was generally very light. Near the epicenter, there are reports of strong shaking. Given that infrastructure in the heavily populated areas surrounding the quake is quite old, there is considerable concern of possible damage to bridges, tunnels and dams.

“According to the Mont Chateau seismograph record in Morgantown, shaking in the area from the earthquake first arrived in just a little over a minute following fault plane rupture. There were some early compressional waves followed by shear waves and then the more intense surface waves — or ground roll — within a minute of arrival. I am not aware of any reports that the earthquake was felt locally in the Morgantown area.

“The earthquake may have occurred along a fault known as the Ramapo Fault. The fault plane solution provided by the USGS indicates the rupture occurred along what is known as a reverse fault. Such a fault accommodates movement of one block over another. The deformation results from compression, one slice of the Earth pushing against another. In this case the fault block, or slice of earth, appears to have been pushed up to the northwest from an east-southeast direction.

“We sit on the eastern margin of the continent, the North American tectonic plate, that currently moves westward at the rate of about 2.5 centimeters per year as the continent and adjacent oceanic plate move away from the Mid-Atlantic Ridge. While earthquakes of this magnitude are infrequent in this area, they have been known to occur roughly twice a century. Historic earthquakes of significance occurred in New York in 1737 and 1884. Generally, earthquake magnitudes in the region are less than three and probably average around two.”— Thomas Wilson, emeritus professor of geology, Department of Geology and Geography, WVU Eberly College of Arts and Sciences