Page:Popular Science Monthly Volume 69.djvu/90

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As to what the future holds in store for the three regions we can only judge by the past. The Charleston earthquake, as far as shocks of any intensity in recent times are concerned, is unique in the Atlantic Coastal region. The equilibrium has probably been regained since the slip of 1886, and it may be ages before another occurs. San Francisco, on the other hand, is in an earthquake region, shocks are of common occurrence, and another of an intensity equal to or greater than the recent disturbance may occur at any time, although, on the other hand, the temporary adjustment brought about by the recent slip tends to decrease the danger of an immediate severe shock.

In the New Madrid area, however, the earthquake of 1811-12 was only one of a series. Cracks may be found with trees fully 200 years old growing in their bottoms, indicating early shakes of equal if not greater intensity than the last. Nor has the movement yet ceased. Every year there are one or more shocks, sufficient to shake objects from shelves, and to seriously affect wells and springs. Only last summer the newspapers were full of accounts of such a shock in southeastern Missouri and adjoining regions—the very area of the New Madrid earthquake. If there have been two or more strong shocks with an intensity far greater than the Charleston quake, and if the readjustment is not completed as is positively indicated by the recent shocks, then there is every reason to believe that disturbances of equal severity may occur in the future. Such quakes, it goes without saying, would be disastrous to such towns as Hickman in Kentucky, Caruthersville, New Madrid, Campbell and others in Missouri, all of which are in the area of disturbance. The larger cities of Cairo and Memphis, although outside the main area, would also probably suffer severely, as they are built on soft deposits overlooking the Mississippi in situations favoring easy slipping towards the streams. Such spots were often severely fissured by the early quake, large masses slipping into the river, and what has occurred once may occur again. St. Louis would also probably be severely shaken, but its buildings are less liable to destruction from a shock originating in the New Madrid area because of the remoteness from the point of disturbance.