Earthquakes seem to be back in the public eye since the San Francisco disaster of last year and the predictions of a Mississippi River jolter due this year.
Actually, the Midwestern earthquake warning has already come true, with a quake that was moderate on the Richter scale. It hit on Sept. 26 and was centered on the New Madrid fault line in Missouri's river country. It also jolted four adjoining states of the Midwest and the Upper South.
In 1811 and 1812, wild destruction of forests, villages and river lands resulted from successive quakes that changed the course of the Mississippi River.
What does the quake record show for Maryland, and how at-risk is the Middle Atlantic area?
Nobody knows for sure. But certainly the region is not immune to measurable, if relatively mild, quakes; there have been a number of those. At the same time, the types of disasters that visit the East Indies, Asia Minor and the Pacific Rim regularly are virtually unknown in the settled parts of eastern North America.
The record shows that at least 23 quakes have been centered in the Maryland-Washington area or Pennsylvania since a quake was recorded in Annapolis in April of 1758.
Three of the most recent of these area rumblers (they often sound like "somebody closing a garage door" or "distant artillery fire," observers have said) have occurred along the Mason-Dixon Line (Oct. 10, 1973), in Washington, D.C. (Feb. 10, 1973) and Marticville, Pa. (Easter Sunday, 1984). They have been typical of the quality of local quakes: often the merest teacup rattlers and only rarely strong enough to snap poles, shatter glass and throw the more important pool tables out of kilter.
The most memorable Maryland quakes happened a century earlier than the Marticville shaker. In that series, the region felt a Baltimore centered-quake in 1883 (March 12), a rattler that rose under the Eastern Shore the next year (April 15) and a Southern Maryland quake on Jan. 2, 1885.
The 1880s seem to have been the most quake-prone decade in Middle Atlantic history. The 1883 earthquake left heavy damage in the Patterson Park area around East Pratt and Gough streets. (For some reason, the elements seem to love causing trouble with the high ground of East Baltimore and Highlandtown, which is also curiously vulnerable to high winds.)
Leafy Catonsville has had two perceptible shakers, on Sept. 1, 1877, and again on April 23, 1910.
If you seek the headquarters of mild Maryland quakes you look just north of the Mason-Dixon Line. That region -- from Wilmington, Del., to the beginning of the Alleghenies -- seems to send out more than its share of radiating rumbles -- epicenters for the mild quakes of the Eastern continental shelf.
As terrible as West Coast quakes have been, an Eastern or Midwestern quake powerful enough to shatter dams, oil plants and power plants would possibly do more to damage the economy since the vast majority of the nation's power is generated in the eastern two-thirds of the nation.
Meanwhile, seismic scholars are hard at work trying to find the key to a predictable earthquake pattern. They've refined probabilities and locational risks vastly in the past half-century. But Mother Nature and the earth's innards seem to resent becoming predictable. Without the gigantic proportion of geological time needed to forecast such temblors, there may not be any earthquake pattern that late 20th century humans can perceive without what amounts to lucky technological guesswork.