Oral Presentation

The Mendocino Triple Junction (MTJ), at the intersection of the San Andreas Fault, the Mendocino Fault, and the Cascadia Subduction Zone, is a complex three-dimensional zone of faulting that represents California’s most seismically active region. I will summarize recent and ongoing geophysical research into this area and how it relates to SCEC’s objectives. Despite the frequent seismic activity of this region, there are still many open scientific questions about earthquake processes, ranging from the basic geometry and mechanisms of faulting to the potential for extreme ground shaking and ground failure. I will focus in part on lessons learned from recent earthquakes near the MTJ, which demonstrate the surprising potential for onshore and offshore faults to interact with each other during seismic rupture. I will also discuss research that explores the consequences of high rates of uplift and convergence in the MTJ. Interestingly, these two themes were also the focus of SCEC’s “special fault study areas” in Southern California (San Gorgonio Pass and Ventura) over a decade ago: regions with dynamic fault interactions, and regions with high convergence and geologic uplift. The MTJ clearly demonstrates how these types of active areas can be used to better understand earthquake processes in general. Accordingly, the plate boundaries and faults at the MTJ have much to teach us and provide many opportunities for further research.