This contribution to the Electronic Seismologist presents the online SRCMOD database of finite‐fault rupture models for past earthquakes, accessible at http://equake-rc.info/srcmod. Finite‐fault earthquake source inversions have become a standard tool in seismological research. Using seismic data, these inversions image the spatiotemporal rupture evolution on one or more assumed fault segments. If geodetic data are used, the source inversions put constraints on the fault geometry and the static slip distribution (i.e., final displacements over the fault surfaces). Joint inversions, using a combination of available seismic, geodetic, and potentially other data, try to match all observations to develop a more comprehensive image of the rupture process. Some joint inversions use all data simultaneously, whereas others take an iterative approach wherein one set of observations is utilized to construct an initial (prior) model for subsequent inversions using other available data.
The field of finite‐fault inversion was pioneered in the early 1980s (Olson and Apsel, 1982; Hartzell and Heaton, 1983). Subsequently, their method has been applied to numerous earthquakes (e.g., Hartzell, 1989; Hartzell et al., 1991; Wald et al., 1991; Hartzell and Langer, 1993; Wald et al., 1993; Wald and Somerville, 1995), while simultaneously additional source‐inversion strategies were developed and applied (e.g., Beroza and Spudich, 1988; Beroza, 1991; Hartzell and Lui, 1995; Hartzell et al., 1996; Zeng and Anderson, 1996). It is beyond the scope of this article to provide a detailed review of source‐inversion methods, their theoretical bases, implementations, and parameterizations; instead, we refer to Ide (2007) for a more comprehensive summary.
Finite‐fault source inversions help to shape our understanding of the complexity of the earthquake rupture process. These source images provide information, albeit at rather low spatial resolution, of earthquake slip at depth, and potentially also on the temporal rupture evolution. Therefore, they represent an important resource for further research on the mechanics and kinematics of earthquake rupture processes. As such, they have a direct bearing on our understanding of earthquake source dynamics. For example, the seminal work of Heaton (1990) on the existence of slip pulses is based on the analysis of a set of finite‐fault rupture models. Building on an early repository of slip models (then maintained by David Wald at the U.S. Geological Survey [USGS]), Somerville et al. (1999), Mai and Beroza (2000, 2002), and Lavallée et al. (2006) investigated slip heterogeneity and source‐scaling relations of finite‐fault rupture models and related their findings to coseismic stress change and near‐source ground motion.
Mai (2004) expanded this early repository of slip models toward a more comprehensive finite‐fault source‐model database. The initial SRCMOD database was manually composed, consisted of about 80 rupture models for which individual HTML files were generated, and provided the first uniform rupture‐model data format. Subsequently, this initial effort was technically improved and expanded to about 150 rupture models (Mai, 2007). The improved database sparked further research to investigate earthquake source complexity and earthquake scaling, also using complimentary data sets (Manighetti et al., 2005; Causse et al., 2010; Strasser et al., 2010; Candela et al., 2011). Using finite‐fault rupture‐model parameters, several authors studied the dynamics of the rupture process and associated ground motion of past earthquakes (e.g., Ide and Takeo, 1997; Zhang et al., 2003; Tinti et al., 2005, 2009; Mai et al., 2006; Causse et al., 2013). Other studies examined stress change on the fault (Ripperger and Mai, 2004), its relation to aftershock occurrence (Woessner et al., 2006) and effects on stress triggering (e.g., Stein, 2003), and postseismic processes (e.g., Ergintav et al., 2009). Detailed information on the kinematic rupture process also helps to shed light on the physics of rupture nucleation, propagation, and arrest (e.g., Mai et al., 2005; Gabriel et al., 2012) and allows the development of relations between slip asperities, temporal rupture properties, and geometrical source effects. These kinematic source parameters can then be related, for instance, to the occurrence of large near‐field velocity pulses (Mena and Mai, 2011). Hence, investigating finite‐fault rupture models with respect to their seismic radiation has immediate practical applications for earthquake‐engineering purposes. Table 1 lists a small selection of published studies that utilized a previous version of the database.
In this contribution to the Electronic Seismologist, we present the expanded, updated, and refurbished SRCMOD database. Readily accessible at http://equake-rc.info/srcmod, the current version of SRCMOD currently offers source modelers, earthquake scientists, and any interested user open access to 300 earthquake rupture models, in a unified representation, published over the last 30 years. This online database also generates enhanced visibility of the research of authors who contribute their rupture models.
In the following sections, we describe the technical aspects and implementation of SRCMOD as an online database and provide an overview of its contents and some general statistics of its current status. We then present a brief analysis on source‐scaling properties using the current SRCMOD database. Potential further technical expansions and additional developments for expanded online access conclude this article.