Dynamic Rupture Scenarios of Large Earthquakes on the Rodgers Creek-Hayward-Calaveras-Northern Calaveras Fault System, California

Ruth A. Harris, Michael Barall, David A. Ponce, Diane E. Moore, Russell W. Graymer, David A. Lockner, Carolyn Morrow, Gareth J. Funning, & Donna Eberhart-Phillips

Submitted August 6, 2020, SCEC Contribution #10294, 2020 SCEC Annual Meeting Poster #151

The Rodgers Creek-Hayward-Calaveras-Northern Calaveras fault system in California dominates the hazard posed by active faults in the San Francisco Bay Area. Given that this fault system runs through a densely populated area, a large earthquake in this region is likely to affect the lives of millions of people. This study produced scenarios of large earthquakes in this fault system, using the tool of spontaneous (dynamic) rupture simulations. These types of physics-based computational simulations require information about the 3D fault geometry, the physical rock properties including fault friction, and the initial stress conditions (e.g., Harris, PAGEOPH, 2004). In terms of fault geometry, the well-connected multi-fault system includes the Hayward fault, at its southern end the Central and Northern Calaveras faults, and at its northern end the Rodgers Creek fault. All of these faults have a record of large earthquakes (e.g., Hecker et al., BSSA, 2005; Kelson et al., USGS Report, 2008; Lienkaemper et al., BSSA, 2010; Oppenheimer et al., JGR, 2010). Geodetic investigations of the fault system’s slip-rate pattern (e.g., Chaussard et al., JGR, 2015) provide images of where the fault surfaces at depth are creeping or locked interseismically, and this information helps us choose appropriate initial stress conditions for our simulations. A 3D geologic model of the fault system provides the 3D rock units and fault structure at depth (Graymer et al., Geology, 2005), while field samples from rocks collected at Earth’s surface provide frictional parameters (Morrow et al., CGS Special Report, 2010). We use this suite of information to investigate the behavior of large earthquake ruptures nucleating at various positions along this partially creeping fault system. We find that large earthquakes starting on the Hayward fault or on the Rodgers Creek fault may be slowed, stopped, or unaffected in their progress, depending on how much energy is released by the creeping regions of the Hayward and Central Calaveras faults during the time between large earthquakes. Large earthquakes starting on either the Hayward fault or the Rodgers Creek faults will likely not rupture the Northern Calaveras fault, and large earthquakes starting on either the Northern Calaveras fault or the Central Calaveras fault will likely remain confined to those fault segments.

Key Words
dynamic rupture, earthquakes, Hayward fault, Rodgers Creek fault, Calaveras fault, geology, geodesy, creeping faults

Harris, R. A., Barall, M., Ponce, D. A., Moore, D. E., Graymer, R. W., Lockner, D. A., Morrow, C., Funning, G. J., & Eberhart-Phillips, D. (2020, 08). Dynamic Rupture Scenarios of Large Earthquakes on the Rodgers Creek-Hayward-Calaveras-Northern Calaveras Fault System, California. Poster Presentation at 2020 SCEC Annual Meeting.

Related Projects & Working Groups
Fault and Rupture Mechanics (FARM)