Static and Dynamic Strain in the 1886 Charleston, South Carolina, Earthquake
Creators
Abstract
During the 1886 𝑀w 7.3 Charleston, South Carolina, earthquake, three railroads emanating from the city were exposed to severe shaking. Expansion joints in segmented railroad tracks are designed to allow railroad infrastructure to withstand a few parts in 10,000 of thermoelastic strain. We show that, in 1886, transient contractions exceeding this limiting value buckled rails, and transient extensions pulled rails apart. Calculated values for dynamic strain in the meizoseismal region are in reasonable agreement with those anticipated from the relation between strain and moment magnitude proposed by Barbour et al. (2021) and exceed estimated tectonic strain released by the earthquake by an order of magnitude. Almost all of the documented disturbances of railroad lines, including evidence for shortening of the rails, can thus be ascribed to the effects of dynamic strain changes, not static strain. Little or no damage to railroads was reported outside the estimated 10⁻⁴ dynamic strain contour. The correspondence between 10⁻³ and 2×10⁻⁴ contours of dynamic strain and Mercalli intensity 9 and 8, anticipated from the dependence of each quantity on peak ground velocity, suggests it may be possible to use railroad damage to quantitatively estimate shaking intensity. At one location, near Rantowles, ≈20 km west of Charleston, a photograph of buckled track taken one day after the earthquake has been cited as evidence for shallow dextral slip and has long focused a search for a causal fault in this region. Photogrammetric analysis reveals that the buckle was caused by transient contraction of <10 cm with no dextral offset. Our results further weaken the evidence for faulting in the swamps and forests south of the Ashley River in 1886, hitherto motivated by the photograph and limited macroseismic evidence for high‐intensity shaking.
Acknowledgement
The authors thank Seth Stein, Andy Barbour, Nicola Litchfield, and an anonymous reviewer for constructive feedback that improved this article. The authors thank Jennifer McCormick at the Charleston Museum for her help in accessing their copy of Wilson’s photo and Abby Cole of the South Caroliniana Library, University of South Carolina, Columbia, South Carolina, who kindly provided a 2400 dpi scan of Sloan’s copy of Wilson’s photo for analysis. The authors thank Jen Christiansen for her help in resolving features of Memberger’s lithograph published 20 November 1886 in Scientific American and Bob Peck of the Historic Mobile Preservation Society for searching for Wilson’s glass plate negative in the Minnie Mitchell Archives. Robert H. Morrow IV of the South Carolina Department of Natural Resources kindly provided a complete set of microfiche copies from Peters and Herrmann (1986). The authors thank Kathleen Franz of the Smithsonian Institution for investigating the possible preservation of the specimen of South Carolina railroad (SCRR) described by Earle Sloan in his 19 October 1886 letter to W. J. McGee, and Tony Diaz for kind assistance with the microfiche reader at the Caltech Fairchild Library. The authors thank Tom Pratt and Martin Chapman for discussions that improved this article. The loan of a Global Navigation Satellite Systems (GNSS) receiver was provided the GAGE Facility, operated by EarthScope Consortium, with support from the National Science Foundation (NSF), the National Aeronautics and Space Administration (NASA), and the U.S. Geological Survey (USGS) under NSF Cooperative Agreement EAR‐1724794. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
Data Availability
Copies of Wilson’s photographs, including that shown in Figure 2, can be downloaded from https://digital.library.sc.edu/collections/charleston-earthquake-1886/ (last accessed January 2024). The U.S. Geological Survey (USGS) 1 m digital elevation model (DEM) data can be downloaded from https://data.usgs.gov/datacatalog/data/USGS:77ae0551-c61e-4979-aedd-d797abdcde0e (last accessed February 2024). Historical topo maps can be downloaded from https://digital.library.sc.edu/collections/topographical-maps-of-south-carolina-1888-1975/ (last accessed February 2024). Historical Mobile Preservation Society is available at https://www.historicmobile.org (last accessed February 2024).
Conflict of Interest
The authors acknowledge that there are no conflicts of interest recorded.
Additional details
Identifiers
- ISSN
- 1943-3573
Funding
- National Science Foundation
- EAR‐1724794
- United States Geological Survey
- National Aeronautics and Space Administration