New Madrid Earthquake:

Inferred from Nuttli, and abridged from Stover and Coffman (1993). (

Carl W. Stover and Jerry L. Coffman. Seismicity of the United States, 1568-1989 (Revised), U.S. Geological Survey Professional Paper 1527, United States Government Printing Office, Washington: 1993. p.67 (

Nuttli, O.W. 1973. The Mississippi valley earthquakes of 1811 and 1812: Intensities, ground motion, and magnitudes, Seismological Society of America Bulletin, v. 63, no. 1, p. 227-248 (

New Madrid Historical Map:

Fuller, Myron L. 1912. The New Madrid Earthquake. U.S. Geological Survey Bulletin 494, United States Government Printing Office, Washington. Plate 1. (

San Francisco Earthquake:

From Lawson (1908) by Boatwright and Bundock (2005). (

Boatwright, John, and Bundock, Howard, Modified Mercalli Intensity Maps for the 1906 San Francisco Earthquake Plotted in ShakeMap Format, U.S. Geological Survey Open-File Report 2005-1135. (

Lawson, A.C. 1908. The California earthquake of April 18, 1906. Report of the State Investigation Commission, Carnegie Institution of Washington, v. 1, 451 p. (