Page:Popular Science Monthly Volume 69.djvu/88

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64
THE POPULAR SCIENCE MONTHLY.

which began on December 16, 1811, continued almost unceasingly for several months, while for more than a year they recurred at frequent intervals. Even at the present time there is probably not a year goes by without a distinctly recognizable shock.

In San Francisco few of the better class of buildings were destroyed, and in Charleston, although the damage was great, few buildings collapsed completely, and the cabins were seldom more than shaken from their foundations. In the New Madrid region there were no high buildings, one story log or frame houses being the rule, but notwithstanding this many are said to have been shaken to pieces by the relatively intense shock.

Again, no progressive wavelike undulation of the surface of any magnitude was recognized at the time of the shock at San Francisco, but at both Charleston and New Madrid the surface rose and fell in waves several feet in height. In Charleston the forests were but little affected, but at New Madrid the trees were often thrown together upon the ground in confused heaps or snapped sharply off near the ground as by an axe.

The streams in the vicinity were little affected by the San Francisco shock, and even at Charleston few if any permanent changes resulted from the earthquake, but in the New Madrid region the effect of the disturbance was very marked. The courses of some of the streams were changed—the water following new cracks instead of the old channels. Others were deflected by warpings of the surface, and still others by sharp uplifts or faults, giving rise to swamps or bodies of open water.

PSM V69 D088 Crater appeared near charleston sc after the shock.png

6. Earthquake Craterlet near Charleston, S. C., as it appeared immediately after the shock.