Earthquakes in Maryland
1999, Reger, James P.
Educational Series 9
In 1973, the Maryland Geological Survey published a pamphlet about earthquakes and Maryland. Fourteen years later, that out-of-print and out-of-date pamphlet was replaced by a larger pamphlet on the same subject. At the time, that seemed adequate to address general inquiries on the subject. After all, the best available information indicated that Maryland had experienced only 22 very minor earthquakes between 1758 and 1987. An average of about one earthquake per decade did not seem to merit widespread interest, from either the general public or the scientific community. Maryland ranked near the bottom of the list of states in terms of earthquake activity.
However, from January 1990 through December 1996, Maryland experienced 35 small tremors-! in Harford County, 2 in Cecil County, 3 in Baltimore County, and 29 in Howard County. In only seven years, the number of known earthquakes in Maryland more than doubled. Never in recorded history had Maryland felt so many earthquakes in such a short period of time.
Such a rash of earthquake activity, minor as it was, fostered a new public interest in and some concern about earthquakes. Then, in 1997, the Federal Emergency Management Agency (FEMA) reclassified Maryland from having a low earthquake hazard to a medium earthquake hazard. It seemed only natural that the 1987 earthquake pamphlet should be updated. It soon became apparent that the pamphlet had outgrown its small format. The result is this booklet.
The purpose of this booklet is two-fold: (1) to update the information from the 1987 pamphlet and (2) to provide enough background that the general public has a reasonable understanding of earthquakes, particularly as they relate to Maryland. Thus, it is hoped that this booklet is sufficiently comprehensive so it can stand alone as a fairly elementary to intermediate, understandable discussion of earthquakes in Maryland, while keeping the more technical aspects to a minimum.