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Fig. 8 Original figure from Bollinger (1977) shows the distribution of intensity values as a func-
tion of epicentral distance for the Charleston earthquake. Black circles indicate inferred hard-rock
intensity values for NM1 based on especially reliable accounts from Ste. Genevieve, Missouri, and
Cincinnati, Ohio
both at a distance of approximately 1200 km. In Terra Haute, Indiana, at a distance
of
1000 km, plaster fell from walls of the Opera House. Following NM1, plaster
fell from walls in Columbia, South Carolina, and a church bell rang at Charleston,
South Carolina, at distances of
960 km, respectively. The Charleston
intensities might have been associated with swaying of tall buildings: plaster fell in
one building in Chicago, Illinois, only above the fourth floor. However, the dramatic
effects following NM1 occurred in a college dormitory building in Columbia, South
Carolina, and in a church steeple in Charleston, South Carolina, also two especially
tall and large structures. Again, the observations for NM1 appear to be comparable
to those for the Charleston earthquake.
830 and
3 Conclusions
Although there has always been good agreement regarding the magnitude of the
1886 Charleston earthquake, there has been considerable disagreement about the
magnitudes of the principle 1811-1812 New Madrid events; there has also been
a prevailing conventional wisdom that the latter events were much larger than the
former. Part of this impression might be rooted in the especially dramatic effects
that the largest New Madrid events produced along riverbanks, in particular along
the Mississippi River. The Charleston earthquake, in contrast, caused widespread
liquefaction and ground failure, but did not have the same impact on a major river.
Nonetheless, considering carefully the intensity distributions of NM1 versus the
Charleston mainshock, one concludes that the former was not significantly larger
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