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 - Loudon 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.
The great earthquake of August 31, 1886, near Charleston, South Carolina, affected a total area with a radius of about 800 miles, including all of Maryland. The Appalachian region had somewhat less noticeable effects than elsewhere. This "shadow zone" extended through the parallel portions of West Virginia, Maryland, and Pennsylvania. The most severe earthquake in Virginia's history (May 31, 1897 in Giles County) shook an area of about 280,000 square miles. Baltimore and southern Maryland along the eastern shore reported distinct shaking. An earthquake centered near Luray, Virginia, (April 9, 1918) reached many points in Maryland: Bagley, Baltimore, Chewsville, Clear Spring (Intensity V), College Park, Takoma Park, and Woodstock.
A magnitude 7.0 earthquake in 1925 (February 28), centered in the St. Lawrence River region near Murray bay, Canada, caused only moderate intensity effects, but was remarkable for the large area affected, which included all of eastern Canada and portions of the United States south of Virginia and west to the Mississippi River. This area covered approximately 2 million square miles. Damage was confined to a narrow belt on both sides of the St. Lawrence River. Baltimore and Overlea reported this earthquake as being felt lightly.
Another Canadian earthquakes, a magnitude 6 1/4 shock on November 1, 1935, near Timiskaming, resulted in only minor damage in the nearby region, but was felt over a great area, extending as far south as Washington, D.C., and as far west as Wisconsin. Felt points in Maryland included Chestertown (intensity IV), Annapolis, Baltimore, Bel Air, Cumberland, Frederick, Hancock, Havre De Grace, Laurel, and Westminster (intensity III or lower).
The felt area of still another earthquake in the St. Lawrence River region reached to Maryland and Pennsylvania and west to Michigan. This shock on September 4, 1944, caused an estimated $2 million damage in the epicentral area. The towns of Baltimore and Westminster, Maryland, were near the extreme southern points reporting this earthquake.
In recent years moderate-sized earthquakes in nearby states have been felt in Maryland with only minimal effects. A single felt report was received from West Hyattsville, associated with a November 19, 1969, earthquake (magnitude 4.3) near Elgood, West Virginia. The February 10, 1972, tremor at Wilmington, Delaware, was felt at Elkton, Maryland. On February 28, 1973, residents throughout a broad area of the middle-Atlantic region of the United States were jolted out of their sleep by shock waves from a minor earthquake near the Delaware - New Jersey - Pennsylvania border. Numerous points in northeastern Maryland reported this earthquake.
Abridged from Earthquake Information Bulletin, Volume 5, Number 4, July - August 1973.
A reader from Annapolis writes: "In your information about earthquakes in Maryland, you say that the first Maryland earthquake occurred on 24 April 1758. I believe this date is an error. The (Annapolis) Maryland Gazette reports on 23 March 1758 that at two minutes before 10 the previous night there had been a 'very considerable Shock of an EARTHQUAKE' that lasted half a minute. Prior to the quake, there was a 'rumbling Noise'. This sounds like the description you give of the 24 April event. I found nothing in the Maryland Gazette for 27 April and 4 May 1758 regarding another such event. Therefore, I believe that the correct date for Maryland's 1758 earthquake was 22 March 1758. This was not the first quake felt in Annapolis. The Cape Ann, MA, quake of 18 November 1755 was felt in Annapolis."
In subsequent correspondence, our reader provided additional information: "The publisher of the Maryland Gazette, Jonas Green, was a science buff. He reports all sorts of natural phenomena -- from a sighting of the aurora borealis to major weather events to experiments with electricity. Green had apprenticed in Philadelphia, knew Franklin, and was a colleague of well-educated Annapolis gentry. ... As far as the epicenter of the March quake being near Philadelphia, I have checked the Philadelphia Gazette as closely as possible for earthquakes in March and April 1758 and found no mention at all of any quake in the area. The only earthquake in Maryland or Pennsylvania that I can find reported in the paper is the one at Annapolis, which was noted in the Pennsylvania Gazette of 13 April 1758."
Our reader makes a convincing case. The citations we have checked for the date of 24 April are all secondary sources, citing earlier references but not quoting them in sufficient detail that we are confident that the dates were correctly preserved from original sources. Earthquake histories are unfortunately not immune to errors in dates, because the information about a specific earthquake may be contaminated by errors that occurred when later authors transcribed information written by earlier authors.
The secondary sources that we have found attribute the shaking of March 22 (Local time; March 23 in Universal Coordinated Time) to an earthquake with an epicenter in Pennsylvania. Our reader's failure to find much on the March earthquake in the Pennsylvania Gazette suggests, however, that the earthquake, if it actually occurred in Pennsylvania, was not centered near regions of European settlement.
The reader is also correct that the 1755 Massachusetts earthquake was felt at Annapolis.
For a list of earthquakes that have occurred since this article was written, use the Earthquake Search.