Abstract

During the 1992 Mw 7.3 Landers earthquake in the eastern California shear zone, only the shallowest part of the central 8 km of the Camp Rock fault apparently ruptured, triggered by coseismic static stress changes. Our detailed tectonic-geomorphic analysis of a 2 km long stretch of the central Camp Rock fault reveals that the 1992 triggered surface rupture differs markedly from earlier primary surface ruptures in terms of its vertical-slip function. We interpret this to be related to a difference in stress directions that induced fault slips: the 1992 static stress changes decreased normal stress on the central Camp Rock fault, thereby inducing a normal component of slip, whereas a minor reverse-slip component is associated with more typical primary seismogenic surface ruptures due to regional north–south compression. Our findings suggest that a detailed geomorphic analysis of a key locality may allow for isolation of triggered surface ruptures from repeated primary surface ruptures identified in paleoseismic studies.

You do not currently have access to this article.