Northeast Arkansas lies within the central Mississippi Valley earthquake region of the United States. The three greatest earthquakes which have affected Arkansas have been the New Madrid earthquake of 1811 to 1813, the Memphis earthquake of 1843, and the Charleston earthquake of 1895. Of the total number of earthquakes which have been felt in Arkansas, 95 per cent have affected the northeast portion of the state while only eight per cent have affected the entire state. The greatest percentage (85 percent) of earthquakes felt in the state has been of medium intensity, rated between I and VII on the Rossi-Forel scale. Only nine percent of the earthquakes felt in the state from 1811 to 1931 have been of sufficient intensity to endanger life. Since 1909 the average periodicity has been one earthquake every 6.7 months. The continuation of frequent small shocks of low intensity in northeast Arkansas may probably prevent the building up of earth stresses which will produce an earthquake of great severity. The earthquakes of northeast Arkansas are apparently caused by movements in the basement rocks underlying the Gulf Coastal Plain.

*Includes: 16 pages, 4 plates and 4 tables

Download text pdf (814 KB)