The Tejon Pass Earthquake of 22 October 1916: An M 5.6 Event on the Lockwood Valley and San Andreas Faults, Southern California

Abstract

On 22 October 1916, a moderate earthquake occurred in the vicinity of Tejon Pass and was felt over much of southern California. An intriguing aspect of this event involves reports of ground cracks that formed during the earthquake. We evaluate the reports of ground cracking and attempt to precisely locate the cracks with respect to active faults; we infer that the earthquake produced minor fault rupture along a newly discovered trace of the easternmost Lockwood Valley fault (formerly mapped as the easternmost Big Pine fault) and/or along the San Andreas fault. We also re-evaluate and present new intensity data, and we use a grid-search algorithm (derived from empirical analysis of modern earthquakes) to find the magnitude most consistent with the reported intensities. Although previous authors have attempted to use intensity data to constrain the magnitude of this event, the algorithm we use provides an alternative and statistically more robust determination of the magnitude. Our results suggest M 5.6 ‫)2.0ם/3.0-(‬ (at 95% confidence) for the 1916 event, which is consistent with earlier work. The 1916 earthquake appears to have been a rare and remarkable event in terms of its size and location and the production of minor surface rupture.

Ground‐rupturing earthquakes on the northern Big Bend of the San Andreas Fault, California, 800 A.D. to Present

“…Historically, three M 5.5– M 5.9 earthquakes produced shaking in the region around Frazier Mountain [ Toppozada et al , ]. The best documented is the 1916 ~ M 5.6 earthquake which caused intensity VII damage and possible triggered slip on sections of the SSAF about 5–10 km west of the site [ Meltzner and Rockwell , ; Toppozada et al , ; Branner , ]. We find no evidence of small, recent slip at the site, indicating that either these sub‐ M 6 events do not produce surface slip or the stratigraphy does not preserve events below about M6.…”

Late Quaternary alluviation and offset along the eastern Big Pine fault, southern California

“…They concluded that a recurrence interval of a few hundred years is not unreasonable on the Pleito-Wheeler Ridge fault system. Meltzner and Rockwell (2004) detailed reconstruction of a 1916 M 5.6 earthquake on the Lockwood Valley fault, formerly thought to be part of the Big Pine fault. Though it may have been linked directly to stress release on the adjacent San Andreas fault, this quake demonstrates that even moderate-intensity earthquakes with long recurrence intervals can generate surface rupture.…”