Scripps Institution of Oceanography

The New Madrid earthquake sequence of 1811-1812 included four shocks which are the largest known for the Central United States. In order to improve our understanding of these earthquakes, estimates of the intensity of shaking were make from contemporary accounts. This report includes estimated intensities at 91 locations for the larger (2 AM) shock on December 16, 1811, from 37 locations for the second-largest on that day, at around sunrise at New Madrid, from 51 locations for the January 23, 1812 shock, and from 48 locations for that of February 2, 1812. The report also includes a discussion of the intensity scale used, and of spurious reports of shaking.