Investigating earthquake scaling relationships from InSAR-derived source parameters
Karlee M. Rivera, & Gareth J. FunningSubmitted September 7, 2025, SCEC Contribution #14910, 2025 SCEC Annual Meeting Poster #TBD
Scaling relationships of earthquake source parameters (fault length, fault width, slip, and seismic moment) provide insight into the underlying physics of earthquakes and their implications for seismic hazard. Earthquake scaling provides invaluable information on which source parameters (e.g., fault length, fault width, and fault area) directly relate to earthquake size, stress drop, and can help determine whether large and small earthquakes scale differently or exhibit self-similarity. Refined scaling relationships will help improve estimates of future earthquake sizes and provide more accurate seismic hazard assessments.
In this study, we use a catalog of models constrained by Interferometric Synthetic Aperture Radar (InSAR) data to investigate scaling relationships of earthquake source parameters. InSAR is capable of providing an earthquake catalog that is suitable for estimating scaling relationships by providing a wide magnitude-range (4.9 ≤ Mw ≤ 9.0) for shallow crustal earthquakes, measurements of key source parameters, such as the length by direct measurement and width by modeling, and also provides global coverage. Our current InSAR-based earthquake catalog contains ~200 events from published studies and 18 of our own models of recent or unmodeled earthquakes in the literature. To model our own earthquakes, we process InSAR data using the ISCE software (Rosen et al. 2012), downsample the data with quadtree decomposition, and invert for the best-fitting source parameters (e.g., length, width, slip) using a rectangular dislocation model and nonlinear optimization.
To evaluate scaling relationships between source parameters (length (L), area (A), width (W), and seismic moment (M0), we perform regression analysis, searching for best-fitting trendlines with (1) a single slope and (2) a change in slope, by minimizing both the L₁ and L₂ norms. Our preliminary results indicate power-law scaling of length-moment (L2∝M0) and suggest that different event types may play a role in scaling with L2.2∝M0 for thrust events and L1.9∝M0 for strike-slip events. The results also show that a change in scaling between small and large earthquakes does not have a statistically significant improvement in fit to the data.
Key Words
InSAR, Scaling Relationships, Source Parameters
Citation
Rivera, K. M., & Funning, G. J. (2025, 09). Investigating earthquake scaling relationships from InSAR-derived source parameters. Poster Presentation at 2025 SCEC Annual Meeting.
Related Projects & Working Groups
Tectonic Geodesy
