Investigating Scaling Relationships of Earthquake Source Parameters using InSAR

Karlee M. Rivera, & Gareth J. Funning

Published September 8, 2024, SCEC Contribution #13922, 2024 SCEC Annual Meeting Poster #077

Scaling relationships of earthquake source parameters, such as the length and width of the fault rupture, slip, and seismic moment, have strong implications for topics in earthquake physics, such as stress drop and earthquake self-similarity. They can also provide better constraints on which fault parameter(s) directly scale with earthquake size, ultimately enabling more accurate estimates of potential future earthquake size for seismic hazard analysis. There are multiple competing scaling relationships models in existence, such as area-moment scaling, power law length-moment scaling, and models with and without scaling breaks, with little consensus as to which features are most robust.

Here we bring a new approach to scaling relationships of earthquake source parameters by using models derived from Interferometric Satellite Aperture Radar (InSAR). InSAR can provide an earthquake source parameter dataset with a wide range of magnitudes, and can also directly constrain measurements of key source parameters (e.g. rupture length), which have previously been suggested to scale with the seismic moment (Scholz, 1982). To produce an InSAR-based dataset that is suitable for evaluating scaling relationships, we compile source parameters of earthquakes from both InSAR-based studies and our own models of earthquakes not represented in the literature. For our own models, we process interferograms using the ISCE software (Rosen et al., 2012), down-sample the data using quadtree decomposition, and solve for the fault parameters using a rectangular dislocation model (Okada, 1985) and nonlinear optimization.

We evaluate the scaling relationships with statistical approaches (e.g. regression analysis with L1-norm and L2-norm penalty) to quantify the relationships between key parameters (e.g. between fault length and seismic moment). We search for the best-fitting trendline testing both a single slope and a change of slope. Preliminary results imply that the scaling relationships resemble power law scaling of length-moment (L2∝M0). We find that event types (e.g. reverse, normal, and strike-slip) may also play a role and alter the scaling relationships.

Key Words
InSAR, Scaling Relationships

Citation
Rivera, K. M., & Funning, G. J. (2024, 09). Investigating Scaling Relationships of Earthquake Source Parameters using InSAR. Poster Presentation at 2024 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy