Heterogeneous fault stresses from previous earthquakes and the effect on dynamics of parallel strike‐slip faults

Abstract

[1] We combine a viscoelastic model for the interseismic process and an elastodynamic model for the coseismic process to explore the dynamics (over multiple earthquake cycles) of two parallel strike-slip faults embedded in a two-dimensional full space. The step over fault geometry results in a buildup of heterogeneous fault stress near the step over. This heterogeneous stress accumulates at the early stage of the evolution of the fault system, and finally stabilizes after a number of earthquake cycles. The heterogeneity in fault stress varies with the geometrical parameters (e.g., width and along-strike overlap/ gap) of the step over, as well as the rupture history of the fault system. This heterogeneous fault stress from previous earthquakes has significant effects on earthquake rupture initiation, propagation, and termination. The locations with a low normal stress level near a step over are favorable points for earthquake initiation. Rupture can jump a 4 km wide compressional step over and a 8 km or wider dilational step over if the fault system has historically experienced many earthquakes. A young step over with less induced heterogeneity allows rupture to jump only smaller step over widths. These results may have important implications for seismic hazard analysis in areas where segmented strikeslip faults predominate, particularly for estimating maximum earthquake potential.

Earthquake Doublet Sequences: Evidence of Static Triggering in the Strong Convergent Zones of Taiwan

“…This result is similar to previous findings with respect to static stress triggering (e.g., King et al 1994;Stein et al 1994;Deng and Sykes 1997;Gomberg et al 1998;Stein 1999;Ammon et al 2008), rather than from dynamic triggering (Freed 2005). Alternatively, the triggering of 2 nd largest earthquake might be a result of rupture propagation beyond fault discontinuities (Kase and Kuge 2001;Duan and Oglesby 2006;Kase and Day 2006). However, the detailed relationship between the events in a doublet should be investigated further.…”

Structural Setting of the 2008 Mw 7.9 Wenchuan, China, Earthquake

“…This suggests that complex oblique-slip earthquakes, such as the Wenchuan event, may have higher limits to breaching segment boundaries than previously recognized. Possible explanations for this distinct behavior include the concept that long-lived or mature faults such as the Beichuan structure may have a greater ability to breach lateral segment boundaries than do less mature faults (Duan and Oglesby, 2006). Alternatively, our analysis suggests that these two segments of the Beichuan fault are linked in the subsurface (Figs.…”

Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3)--The Time-Independent Model

“…Both of these issues were subsequently, and dramatically, exemplified following the UCERF2 publication, by events such as the 2011 M 9 Tohoku earthquake with respect to segmentation (e.g., Kagan and Jackson, 2013), the 2011 M 6.3 Christchurch earthquake in terms of spatiotemporal clustering (e.g., Kaiser et al, 2012), and both the 2010 M 7.2 El Mayor-Cucapah and 2012 M 8.6 Sumatra earthquakes in regard to multifault ruptures (e.g., Hauksson et al, 2011;Meng et al, 2012). There is also now a substantial body of literature on the viability of multifault ruptures (e.g., Segall and Pollard, 1980;Knuepfer, 1989;Harris et al, 1991;Harris and Day, 1993;Lettis et al, 2002;Duan and Oglesby, 2006;Wesnousky, 2006;Shaw and Dieterich, 2007;Black and Jackson, 2008;and Finzi and Langer, 2012).…”