A Comprehensive Search for Repeating Earthquakes in Northern California: Implications for Fault Creep, Slip Rates, Slip Partitioning, and Transient Stress

Abstract

Repeating earthquakes−earthquakes that rupture the same fault area with sources of similar magnitude and mechanism−are playing an increasingly important role in the study of fault processes and behavior, and have the potential to improve hazard assessment, earthquake forecast, and seismic monitoring capabilities. The recurrence interval of large repeating earthquakes is a crucial parameter when estimating hazard probabilities (Ellsworth, 1995; WGCEP, 1999). Repeating earthquakes, in particular smaller magnitude events, often produce sequences of remarkable periodicity that indicate characteristic behavior (Ellsworth, 1995;Nadeau & Johnson, 1998;Vidale et al., 1994). Because recurrence models that describe cycles of repeating earthquakes have at least modest predictive power (Matthews et al., 2002;Zechar & Nadeau, 2012) they play an increasingly important role in determining earthquake risk.

Marine Paleoseismic Evidence for Seismic and Aseismic Slip Along the Hayward‐Rodgers Creek Fault System in Northern San Pablo Bay

“…These estimates of vertical creep along the Hayward fault are comparable to our estimate in San Pablo Bay and further support our interpretation that this vertical deformation is the result of aseismic creep. In addition, the horizontal creep rate inferred here is similar to the 4-12 mm/yr range estimated from repeating earthquakes along the Hayward fault beneath southern San Pablo Bay (Shakibay Senobari & Funning, 2019;Waldhauser & Schaff, 2021). Combined, these observations suggest the extent of significant (≥3 mm/yr) near surface creep on the Hayward fault likely extends >10 km north of Point Pinole.…”

“…Repeating earthquakes identified along the Hayward fault beneath southern San Pablo Bay (Figure 1 and Figure S4 in Supporting Information S1) were used to suggest the fault is creeping at depth at a rate of between ∼4 mm/yr (Shakibay Senobari & Funning, 2019;Shirzaei et al, 2013) and ∼12 mm/yr (Waldhauser & Schaff, 2021). Here we present a multi-disciplinary approach to conducting on-fault marine paleoseismologyand present evidence for both vertical aseismic creep and coseismic (Waldhauser & Schaff, 2021); green stars, existing paleoseismic trench sites discussed in this paper. MH, Masonic Home (Lienkaemper & Borchardt, 1996); MV, Mira Vista (Lienkaemper et al, 1999); SP, San Pablo (this study); TG, Triangle G (Hecker et al, 2005); TL, Tyson's Lagoon (Lienkaemper et al, 2002).…”

“…The most recent large earthquake on the Hayward fault occurred in 1868 and paleoseismic evidence suggests a mean recurrence time of 161 ± 65 years (Lienkaemper et al, 2010). The Hayward fault is one of the most well-studied creeping faults in the world, with observations from creepmeter, alignment array, repeating earthquake, GPS, and InSAR data (Bürgmann et al, 2000;Chaussard et al, 2015;Lienkaemper et al, 2014;McFarland et al, 2014;Nadeau & McEvilly, 1999;Schmidt et al, 2005;Shirzaei et al, 2013;Waldhauser & Schaff, 2021).…”

“…There is a distinct horizontal surface creep rate gradient across the bay with an estimated 5.0 mm/yr along the northern Hayward fault just south of Point Pinole and no resolvable creep (0.3 mm/yr) along the southern Rodgers Creek fault at Wildcat Mountain (McFarland et al, 2014). Repeating earthquakes identified along the Hayward fault beneath southern San Pablo Bay (Figure 1 and Figure S4 in Supporting Information S1) were used to suggest the fault is creeping at depth at a rate of between ∼4 mm/yr (Shakibay Senobari & Funning, 2019;Shirzaei et al, 2013) and ∼12 mm/yr (Waldhauser & Schaff, 2021). Here we present a multi-disciplinary approach to conducting on-fault marine paleoseismologyand present evidence for both vertical aseismic creep and coseismic (Waldhauser & Schaff, 2021); green stars, existing paleoseismic trench sites discussed in this paper.…”

“…A number of studies have identified repeating earthquakes along the submerged trace of the Hayward fault in San Pablo Bay (see Figure S4 in Supporting Information S1; Shakibay Senobari & Funning, 2019;Shirzaei et al, 2013;Waldhauser & Schaff, 2021). These events rupture the same fault patch repeatedly and are thought to be loaded by surrounding fault creep (Nadeau & McEvilly, 1999).…”