Triggered aseismic fault slip from nearby earthquakes, static or dynamic effect?

Abstract

[1] Observations show that an earthquake can affect aseismic slip behavior of nearby faults and produce ''triggered aseismic fault slip.'' Two types of stress changes are often examined by researchers as possible triggering sources. One is the static stress change associated with the faulting process and the other is the dynamic stress change or transient deformation generated by the passage of seismic waves. No consensus has been reached, however, regarding the mechanism(s) of triggered aseismic fault slip. We evaluate the possible triggering role of static stress changes by examining observations made after 10 large earthquakes in California. Most of the nearby fault segments that slipped aseismically were encouraged to move by the imposed positive changes in static Coulomb Failure Stress (CFS). Nonetheless, three discrepancies or failures with this model exist, which implies that static stress triggering either is or is not the sole mechanism causing the observed triggered slip. We then use a spring-slider system as a simplified fault model to study its slip behavior and the impact of transient (dynamic) loading on it. We show that a two-state-variable rate-dependent and state-dependent frictional law can generate creep events. Transient loads are then put into the system. Certain types of them can cause a large time advance of (or trigger) the next creep event. While our work examines triggered creep events near the surface, it may well have implications for the occurrence of similar events near the bottom of the seismogenic zone where a transition in frictional stability occurs.

Shallow geological structures triggered during the Mw 6.4 Meinong earthquake, southwestern Taiwan

“…Numerical modeling (Du et al 2003) later supported this hypothesis. The faults mentioned above, on which aseismic slip has been reported or inferred, are located within the Lower Gutingkeng mudstone formation.…”

Transient creep, aseismic damage and slow failure in Carrara marble deformed across the brittle‐ductile transition

“…It also illustrates the possible role played by pore fluid diffusion as an incubation process for delayed failure triggering. While in the laboratory, this could have implications for the mechanics of the lower seismogenic zone [Du et al, 2003]. There, ductile minerals prevalent in Earth's crust, such as quartz and feldspar are predicted to behave in a similar fashion above 300°C as calcite does at room temperature [Tullis and Yund, 1992].…”

“…The mechanics of the transition depends both on extrinsic variable (state of solid stress, pore pressure, temperature, fluid chemistry and strain rate) and intrinsic parameters (modal composition of the rock, porosity, crack and dislocation density) [Paterson and Wong, 2005]. The deformation mechanisms operative during the transition occur on scales ranging from microscopic to macroscopic and have profound influence on the spatiotemporal evolution of stress and deformation [Du et al, 2003], as well as in the coupling of crustal deformation and fluid transport [Miller, 2002]. Thus, investigating the interplay between intragranular plasticity and cracking in the laboratory may be critical in order to understand the mechanics of the lower seismogenic zone and/or the early stages of earthquake nucleation [Rice and Cocco, 2006].…”

Slip rate and mode of the Feldbiss normal fault (Roer Valley Graben) after removal of groundwater effects

“…5). Owing to the negligible static stress change induced by the earthquake at Sittard, I interpret the coseismic displacement of the Feldbiss fault as a creep event dynamically triggered by the passage of trapped seismic waves [36][37][38]. This might have resulted in small changes in the hydraulic conductivity across the fault at shallow depth, inducing the observed later increase in DGW2, and in a subsequent transient instability causing oscillatory motions.…”