Caption:
Fig. 1. Study region and fault geometry. ( A) Southern
California study region, with shaded relief in background.
Thin lines: regional faults; dashed box: region in (B).
LA: Los Angeles; SAF: San Andreas fault; SJF: San Jacinto
fault; SMF: Sierra Madre fault; CF: Cucamonga fault. ( B)
Fault geometry, regional stress orientation, and fault
rakes due to regional stress, with shaded relief in
background. Heavy solid lines show surface fault traces,
dotted lines show surface projections of down-dip
geometry. Arrows show fault rakes, with values in degrees.
CP: Cajon Pass. ( C) Fault surfaces as viewed from the
northeast looking over the SAF toward the Los Angeles
metropolitan area.
Context:
The northern edge of the densely populated Los Angeles
metropolitan region is bounded by the Sierra
Madre-Cucamonga (SMF-CF) thrust fault system, which
produced the Mw= 6.7 1971 San Fernando earthquake and may
generate events up to Mw= 7.5 ( 7). To the east and north
lie the San Andreas (SAF) and San Jacinto (SJF)
right-lateral strike-slip fault systems; each may slip in
events exceeding Mw= 7.0, and events of Mw= 7.8 occurred
on the SAF in 1685 and 1857 ( 8). Here, we examine past
and potential ruptures on the SAF, SJF, CF, and SMF ( Fig.
1 and Table 1 ) ( 9). We model both static stress transfer
between separate events and dynamic rupture propagation
during a single event, so that we can understand a wider
range of possible fault interactions. In doing so, we find
faults whose ruptures encourage ruptures of other faults
at later times, as well as sets of faults that may fail in
a single, large, complex event.
Source:
Anderson, G., Aagaard, B., & Hudnut, K. (2003). Fault
Interactions and Large Complex Earthquakes in the Los
Angeles Area. Science, 302(5652), 1946-1949.
