Physics‐Based Earthquake Simulations in Slow‐Moving Faults: A Case Study From the Eastern Betic Shear Zone (SE Iberian Peninsula)

Abstract

Earthquake hazard forecasting often has to deal with the scarcity of seismicity data, the complexity of fault segmentation, the uncertainties derived from the characterization of seismogenic sources, the dynamics of earthquake rupture and the recurrence model used. Instrumental earthquake recordings are available only since about 1900 and they are not reliable until several decades later. There are a few regions with representative historical data of large earthquakes for more than 2000 years in Italy (Boschi, 2000), Japan (Ishibashi, 2004), and China (Liu et al., 2011) that allow acquisition of reliable major earthquake magnitudes and recurrence statistics. In regions with low to moderate seismicity, such as some zones of the western Mediterranean or intracontinental areas, earthquake hazard estimation is especially challenging (see e.g., Estay et al., 2016;Gamage & Venkatesan, 2019;Perea & Atakan, 2007). Most of the large, and consequently damaging earthquakes, have recurrence times on the order of hundreds or thousands of years. Since historical catalogs are often scarce and imprecise, the paleoseismic record provides valuable data about rare but devastating major events and long-term recurrence times, but these data usually have large uncertainties (McCalpin, 2009). Often, the slow fault systems, besides generating low seismicity in terms of frequency, show little geomorphological expression. This makes it difficult to define the segmentation of fault traces and the parameters relating to their 3D geometry and their kinematics. Fault system geometry also plays an important role in the stress interactions that control the earthquake ruptures and therefore magnitude and recurrence statistics (e.g.

Impact of Variable Fault Geometries and Slip Rates on Earthquake Catalogs From Physics‐Based Simulations of a Normal Fault

“…The combination of parameters that resulted in this catalog have rate-and-state friction parameters a = 0.001 and b = 0.004, an initial shear stress of 60 MPa and a normal stress of 120 MPa. These normal and initial shear stress values are similar to those used in previous studies employing RSQSim (e.g., Herrero-Barbero et al, 2021;Howarth et al, 2021;Shaw et al, 2022) and we use them for consistency with that previous work. We note that the normal stresses are higher than those employed by some other quasi-static and dynamic multi-cycle earthquake simulators (50 MPa; Cattania, 2019;Lapusta & Liu, 2009;Perry et al, 2020;Thomas et al, 2014).…”

“…This difference may be related to the way the rate‐and‐state equations are simplified differently in different models; it is not important for our results because in the RSQSim simplification there is a trade‐off between normal stress and the imposed rate‐and‐state (a–b). Finally, a dynamic stress overshoot factor of 10% and an alpha‐coefficient α = 0.25 were applied in order to deal with the dynamic limitations (Gilchrist, 2015; Herrero‐Barbero et al., 2021; Richards‐Dinger & Dieterich, 2012).…”

“…In this study, we examine the effect of fault geometry and spatial variability of fault slip rates on the synthetic earthquake catalogs produced by RSQSim, a physics‐based earthquake simulator (Richards‐Dinger & Dieterich, 2012). Published studies demonstrate that the MFDs of simulated earthquakes using RSQSim can be similar to historical earthquakes in many regions of active faulting (e.g., Herrero‐Barbero et al., 2021; Shaw et al., 2022). These similarities support the use of RSQSim for either estimating seismic hazard or for constraining parameters input to seismic hazard models.…”

“…The relatively short duration and incompleteness of historical earthquake and paleoseismic records, respectively, has led to the development and utilization of the physics‐based earthquake simulators (e.g., Console et al., 2017; Richards‐Dinger & Dieterich, 2012; Robinson & Benites, 1995). Earthquake simulators use physics of stress transfer and frictional resistance to describe earthquake sequences (Tullis et al., 2012); they can produce catalogs of millions of synthetic events over thousands to millions of years using predefined fault geometries and slip rates as input parameters (e.g., Álvarez‐Gómez et al., 2023; Console et al., 2022; Herrero‐Barbero et al., 2021; Kourouklas et al., 2021; Shaw et al., 2022, 2018). These simulators have the potential to be a useful addition to seismic studies for several reasons.…”

Improved Geological Slip Rate Estimations in the Complex Alhama de Murcia Fault Zone (SE Iberia) and Its Implications for Fault Behavior

“…Another possibility is that stress changes occurred at a larger scale, related to static and/or dynamic interaction between the AMF and other EBSZ faults. The recent work by Herrero-Barbero et al (2021) suggested that fault interaction is a possibility in the EBSZ by means of earthquake rupture propagation across fault sections. This study used the RSQSim code (Dieterich & Richards-Dinger, 2010), which is a physics-based earthquake simulator that allows to model earthquake occurrences in time and space, while also considering the physical characteristics of earthquake ruptures at the fault system scale.…”