Geologists recorded a small earthquake that occurred — but apparently escaped the notice of residents — on Saturday afternoon in Morris Plains.
The tremor, registering a minor 1.3 on the Richter Scale, was reported by Columbia University's Lamont-Doherty Observatory to the Morris Plains Police Department, which issued an advisory to residents on Monday morning.
"To date (there) were no reported injuries or damage related to the earthquake and no Morris Plains residents reported any activity to this agency," Chief Jason A. Kohn wrote.
Lamont-Doherty spokesperson Kevin Krajick said the quake was pinpointed to a shallow depth of 6 kilometers just north of Grannis Avenue, between mountain and Sun Valley ways, about 500 feet southeast of Mountain way School.
"It was a very small earthquake at a very shallow depth," Krajick said. "Most people would not feel an earthquake that small unless they were absolutely right under it, if that."
Krajick said major earthquakes occur at depths of as much as 10-20 miles "or even more."
Lamont-Doherty seismologist Mitch Gold said there was no particular fault line to identify under Morris Plains.
"It's not like California, where the fault lines are more defined," Gold said.
Gold said the northern New Jersey region had been quiet of late, but several minor quakes were felt last year in Kinnelon, Butler, Riverdale and other points in northern Morris in the area of the Ramapo fault line. Butler police received several calls on Aug. 8 from residents who felt a small earthquake.
"Yes, we got a bunch of calls about it, between 9:30 and 10:30," Butler Police Lt. Mike Moore said.
The 1.0 magnitude quake, which was registered by the USGS at 10:01 p.m., was centered near the eastern shore of the Wanaque Reservoir in Wanaque, about six miles from the Morris County borders of Butler and Riverdale, according to the United States Geological Survey.
Another quake — a 1.1 magnitude felt in Kinnelon and Butler — occurred at 4:06 a.m. on July 4, at a depth of two kilometers and occurring about one kilometer east southeast of Kinnelon, according to the USGS.
Three more minor earthquakes jolted northern Morris County on Feb. 21, three days after a larger quake was felt in the same area. The epicenter of those earthquakes was about 1 mile northeast of Kinnelon. All were minor tremors, the first registering a magnitude of 0.6 at 10:07 a.m., and the second registering a 0.1 at 10:48 a.m. Both of those tremors were estimated to have originated at a depth of 1 mile. A third and final quake registered a 0.2, originating at a depth of 0.3 miles.
The USGS says earthquakes with a magnitude between 1.0 and 3.0 aren't typically felt. But Butler Police Chief Ciro Chimento previously confirmed his department received more than 1,000 calls about a 1.6-magnitude quake that occurred on the evening of Feb. 18.
Another magnitude-2.07 earthquake also hit northern New Jersey on Jan. 2. Mahwah residents as well as those in New York's Rockland County also reported feeling that quake.
Earthquakes are generally less frequent and less intense in the northeast compared to the U.S. Pacific Coast, according to the New Jersey Department of Environmental Protection. But due to geological differences between the regions, earthquakes of similar magnitude affect an area 10 times larger in the Northeast U.S. compared the West Coast.
New Jersey has never recorded a fatality due to an earthquake, according to the DEP.
Staff Writer William Westhoven: 973-917-9242; wwesthoven@gannettnj.com.
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