Earthquakes in the Tunkhannock Creek
Atlas Area of Northeastern, PA
Most earthquakes are associated
with the boundaries of tectonic plates.Pennsylvania,
however, is about 2,000 miles west of the closest active boundary, the
mid-Atlantic Ridge, which runs down the center of the Atlantic Ocean.However, about 200 million years ago, when the supercontinent Pangea
was breaking up and the Atlantic Ocean was first opening, the east coast of
North America was an active boundary zone
Northeastern Pennsylvania is a
seismically quiet area compared to more active zones along the west coast,
such as the San Andreas fault area.However,
large quakes from other areas are perhaps occasionally felt here.The great New Madrid, MO earthquakes of 1811-12 would have shaken our
area, as would have the Charleston, SC quake of 1886.Pennsylvania has several areas that are more seismically active than
Northeastern Pennsylvania (NEPA), including the Lancaster, York, Philadelphia, Reading, and Erie areas.The greatest quake recorded in PA was the 5.2 (Richter) tremblor that
occurred September 25, 1998, near Pymatuming Reservoir in the northwest part of
the state.
Within the Tunkhannock Creek watershed, the only
quake in recent times
was a 1.8 quiver that had its epicenter at Hop Bottom, Susquehanna County, on
August 14, 1982.Three other
nearby events were recorded prior to 1970: two in Mill City, Wyoming County (1950, 3.3
magnitude; 1963, 3.4 magnitude), and one in Fleetville,
Lackawanna County, in 1940.
None of these, however, had a maximum intensity (according to the
Modified Mercalli Intensity Scale) of IV or greater, and hence are considered
to be minor.A level IV earthquake
would be felt during the day by many indoors, but outdoors by few.Dishes, windows, and doors are disturbed, and walls make creaking sounds.
References:
Scharnberger, C.1989.Earthquake Hazard in Pennsylvania. Pennsylvania
Geologic Survey, 4th series, Educational Series 10, 14p.
Schultz, C. H., ed.1999.The Geology of
Pennsylvania.Pennsylvania
Geologic Survey and Pittsburgh Geological Society, Special Publication 1.888 pp
