Abstract

We present the results of intensive field investigations of the scarp associated with the 23 February 1892 earthquake in northern Baja California. Newly recognized additional offsets suggest the rupture was about 58 km in length, twice as long as previous estimates. Slip produced in the 1892 event varied from purely dextral slip near the international border to roughly 1:1 oblique-normal slip farther south along the 2–4-km-deep portion of the Laguna Salada basin. The portion of the 1892 rupture with oblique-normal slip comprises a number of short, poorly organized, and discontinuous fault scarps with heights that vary in concert with their strike. Slip was linked farther south to a short, purely normal fault that forms a large releasing bend at the southern termination of the fault zone. Given the distribution of slip along the earthquake and a likely range of locking depths, we conclude the 1892 earthquake was between Mw 7.1–7.3 in magnitude, consistent with previous estimates from macroseismic observations. The length of the Laguna Salada fault that ruptured in 1892 also accommodated minor normal sense displacement along much of its length in the recent 2010 Mw 7.2 El Mayor–Cucapah earthquake, which guided the remapping effort.

Online Material: Table of displacement measurements with uncertainty, location, waypoint number, soil unit designation, and the strike, dip, and type of feature measured.

You do not currently have access to this article.