Earthquakes did not appear on the hazard list for Maryland for a good number of years until 2011 when the Virginia earthquake rattled Washington D.C. and Maryland, including Harford County.
The geology of the east coast and the Appalachian Mountains features many faults, or cracks, in the earth's crust which can experience movement from time to time. It is this movement along a fault line which generates an earthquake. Maryland has an extensive history of earthquake occurrence, but fortunately many of these events are weak and occur very seldom. For more information regarding earthquakes in Maryland, please visit the Maryland Geological Survey's webpage on Maryland Earthquakes.
Additionally, the State of Maryland maintains a seismometer for measuring earthquake activity and this seismometer can detect earthquakes from all over the globe. The Maryland Seismic Network provides high quality, real-time data on local earth movements and earthquakes in Maryland and other more distant earthquakes around the globe. If you think you feel something that could be an earthquake, please visit the Maryland Seismic Network webpageto access real-time Maryland earthquake information.