Reply #3: Earthquakes in Maryland... [View All]

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The earliest recorded earthquake in Maryland occurred in Annapolis, on April 24, 1758. The shock lasted 30 seconds and was preceded by subterranean noises. Additional felt reports were received from a few points in Pennsylvania.

The great earthquake series of 1811 -1812 centered near New Madrid, Missouri, affected an area of 2 million square miles, including Maryland. A moderate-sized earthquake on March 9, 1828, was felt over all of Virginia, West Virginia, and portions of neighboring states, including Maryland. The effects at Baltimore resulted in considerable shaking of doors and agitation of other objects. The center of this earthquake was not accurately fixed, but it was probably in southwest Virginia. Another shock centered in Virginia, on August 27, 1833, was felt noticeably in Baltimore. A similar pattern followed on April 29, 1852, from a moderate shock in southwestern Virginia. Considerable alarm was noted in Baltimore, while Annapolis was reported as merely feeling the tremor.

Harford County, Maryland, was shaken by two or three earthquakes the night of March 11 and the morning of March 12, 1883. The intensity was in the IV - V range, (clocks stopped at Fallston) with felt points also noted in Baltimore County.

Another moderate shock occurred less than two years later, on January 2, 1885, in an area near the Frederick County, Maryland - Ludon County, Virginia, border. Maximum intensity reached V, with the total felt area covering more than 3,500 square miles. Clarke, Fairfax, Fauquier, and Shenandoah Counties, Virginia, also reported this earthquake.

Since 1885, earth vibrations felt in Maryland have been associated with sources for adjacent states and points as far away as the St. Lawrence Valley and Timiskaming, Canada.
http://earthquake.usgs.gov/regional/states/maryland/history.php