Current Abstract

June 10th, 2025 Meeting Abstract

“When is the San Andreas Actually the San Andreas? Building a Plate Boundary from Bakersfield to the Bay and Beyond“

Presented by: 

Matthew Herman, Ph.D.

Abstract: 

The San Andreas serves as the transform plate boundary between the Pacific and North American plates, extending along most of California. The San Andreas system is relatively young, geologically speaking; it first began replacing the existing subduction zone ~30 million years ago near the latitude of Bakersfield, and since that time has lengthened to its present-day, 1000+ kilometer extent. In this talk, I will address the question of how this major plate boundary reorganization occurred, and specifically the geologic processes that led to the northward growth of the San Andreas transform plate boundary as it formed in the wake of the retreating subduction zone. This plate boundary reorganization continues to operate today from the Bay Area to the Mendocino triple junction, and plays a major role in defining the crustal architecture and faulting. Perhaps most surprisingly, the San Andreas fault from the Bay Area to the Mendocino triple junction is *not* actually the lithosphere-scale San Andreas plate boundary. This has implications for continuing earthquake hazards in the region, as well as understanding what exactly happened in the famous 1906 San Francisco earthquake.

Biography:

I am an Assistant Professor (soon to be an Associate Professor!) in the Department of Geological Sciences at California State University, Bakersfield. In addition to teaching courses in natural hazards, geophysics, plate tectonics, and earthquakes, I work with students on a variety of different research topics. My work primarily focuses on lithospheric geodynamics, a fancy term for quantitative plate tectonics. Specifically, I am interested in what processes on Earth lead to earthquakes and in turn what earthquakes can tell us about the way the Earth works. I have several ongoing projects, including the evolution of the northern San Andreas plate boundary (this talk), the effects of plate boundary coupling on subduction zone earthquake cycles, the drivers of plate boundary deformation in the Mediterranean Sea and southeast Asia, and the geomechanical effects and induced earthquake potential of underground carbon or hydrogen storage. If you ever have an earthquake question feel free to reach out, or look for me to be talking about recent events on the local news!