Sequences of seismic and aseismic slip on bimaterial faults show dominant rupture asymmetry and potential for elevated seismic hazard

Evidence of Early Supershear Transition in the Feb 6th 2023 Mw 7.8 Kahramanmaraş Turkey Earthquake From Near-Field Records

“…Other mechanisms that may have favored a rapid supershear transition include on-fault stress or strength heterogeneities [26,27] or off-fault material complexities [28,29]. The extended propagation of the rupture in the NNE direction may also suggest the existence of a velocity contrast across the fault surface and a bimaterial effect [30,31,32]. Overall, we hope that further studies of the regional stress field and the structure of the ground motion records will reveal more details about the nature of this complex multi-segment rupture that led to such a large-scale human tragedy.…”

Internal Structure of the Central Garlock Fault Zone From Ridgecrest Aftershocks Recorded by Dense Linear Seismic Arrays

“…The key results of this study and their relevance to various topics are: The inferred velocity contrast can produce statistically preferred rupture propagation directions of earthquakes (to the east‐north‐east for standard subshear ruptures and to the west‐south‐west for supershear ruptures) on the imaged section of the Garlock fault. This may influence significantly the spatial distribution of the radiated seismic waves and sequences of earthquakes on the fault (e.g., Abdelmeguid & Elbanna, 2022; Ampuero & Ben‐Zion, 2008; Brietzke et al., 2009; Shlomai & Fineberg, 2016). The bimaterial interface is continuous along the imaged section of the fault but likely terminates at some point southwest of array A5.…”

“…Detailed information about the subsurface structure of the Garlock fault (e.g., across‐fault velocity contrast, dip, and damage zone properties) can improve the accuracy of locations, focal mechanisms, and other parameters derived for earthquakes on the fault (e.g., McGuire & Ben‐Zion, 2005; McNally & McEvilly, 1977; Oppenheimer et al., 1988), contribute to the understanding of spatio‐temporal earthquake patterns (Abdelmeguid & Elbanna, 2022; Brietzke & Ben‐Zion, 2006; Thakur & Huang, 2021; Thakur et al., 2020), and provide constraints for modeling future ruptures and expected ground motion (e.g., Blisniuk et al., 2021; Brietzke et al., 2009; Fuis et al., 2012; Share & Ben‐Zion, 2018). Moreover, recent studies have shown that local variations of seismic properties of fault zone structures can affect the wavefield far from the fault (e.g., Schliwa & Gabriel, 2022; Yeh & Olsen, 2022).…”

Modeling Sequences of Earthquakes and Aseismic Slip (SEAS) in Elasto‐Plastic Fault Zones With a Hybrid Finite Element Spectral Boundary Integral Scheme

“…Here, the V tr is chosen such that the relative contribution of the radiation damping term to the quasi‐static stress drop R = η RD V / τ qs remains small in magnitude R ∼ 10 −4 . For more details on switching between the quasi‐dynamic and fully dynamic solver we refer the reader to Abdelmeguid and Elbanna (2022) (Section 3.2).…”

“…Since their emergence early 2000s, SEAS models have provided crucial insights on natural earthquake phenomena such as spontaneous nucleation of earthquakes (Lapusta & Rice, 2003; Lapusta et al., 2000), slow slip events (Barbot, 2019), small repeating earthquakes (Chen & Lapusta, 2009), and seismicity swarms (Zhu et al., 2020). Additionally, advancement in computational tools enabled investigations of the long term effects of thermal pressurization (Noda & Lapusta, 2013), poroelasticity (Torberntsson et al., 2018), quasidynamic slip evolution and fault roughness (Cattania & Segall, 2021; Heimisson, 2020), bi‐material effects (Abdelmeguid & Elbanna, 2022), low velocity fault zones (Abdelmeguid et al., 2019; Thakur et al., 2020), and inelastic deformations (Erickson et al., 2017; Mia et al., 2022; Tal & Faulkner, 2022) on the evolution of aseismic and coseismic slip. In most elastic models the overall pattern would converge to a statistically steady solution independent of the initial conditions after this transitional spin‐up period (Erickson & Jiang, 2018).…”