THE IMPACT OF THE CHARLESTON EARTHQUAKE OF 1886 ON THE NASCENT SCIENCE OF SEISMOLOGY (Invited Presentation)

The destructive 1886 Charleston, earthquake occurred soon after the birth of seismology as a science. It provided data to test and improve upon the ideas and methods of Mallet. It attracted many investigators, including in early September, McGee (US Geological Survey), Mendenhall (US Signal Service), and Hayden (US Navy). Locally, Sloan studied the epicentral tracts for two months, and Manigault (a Professor at Charleston College) and other members of Charleston’s Elliot Society reported on the effects of the earthquake on structures.

Within two weeks reports of the earthquake were published in Science and Nature. The epicentral data were complemented by more distant data. The initial data collected by these observers, included 4000 accounts from 1600 locations. These data included more than 300 accurate (due to the existence of a daily-calibrated standard-time system) times of passage of the “earth” waves, and included 45 stopped pendulum clocks. There were 60 accounts from distances greater than 800 km. Analyses of these data by Dutton and Hayden (1887) led to three discoveries; the identification of three foci, a new method of determining the focal depths and a method of calculating the velocity of “earth” waves. In his elaborate report, Dutton(1889) reduced the source to two foci at Woodstock (focal depth 19 km) and Rantowles (13km) and determined an average seismic velocity of 5.2 km/s. In a combative discussion with authoritative Prof. Newberry who suggested that earthquakes were caused by “the shrinking caused from the loss of heat, of the heated interior of the earth”, Hayden successfully argued for Mallet’s view that “an earthquake is the passage of waves of elastic compression in the crust of the earth.”