A 1.5 magnitude earthquake was reported early Tuesday night roughly 30 miles from the Maryland border, according to the Maryland Geological Survey.
The quake was registered around 6:42 p.m. and originated about a mile northwest of Shippensburg, Pa.
This is the second earthquake reported near Maryland this year. The first was a 4.7 earthquake 136 miles off the coast of Ocean City in January.
According to the USGS, an earthquake’s severity is measured both for intensity and magnitude. Intensity refers to the observable effects of a quake and can vary from location to location. Magnitude measures the amount of seismic energy, or vibrations that travel through the earth, released at the center of the earthquake.
The standard for magnitude measurement is called a Richter scale, which is logarithmic — a term that means the Pennsylvania earthquake measuring at 1.5 on the Richter scale was 10 times less powerful than a 2.5 earthquake and 100 times less powerful than a 3.5.
Scientists use devices called seismographs to measure magnitude. The Maryland Geological Survey has two seismic sensors, one in Baltimore County and another in Garrett County.