Physics-based broadband characterization of weak earthquakes.

Area of Science:

• Seismology
• Earthquake Science
• Geophysics

Background:

• Standard seismological methods lack resolution for small earthquake rupture complexity.
• Advanced dynamic rupture models are typically applied to large earthquakes.

Purpose of the Study:

• To develop a Bayesian dynamic inversion for analyzing small earthquakes.
• To extend dynamic rupture modeling to capture small-scale fault heterogeneity.

Main Methods:

• Developed a Bayesian dynamic inversion using station-specific source spectra up to 25 Hz.
• Applied heterogeneous parameterization for slip-weakening friction on a finite fault.
• Achieved resolution down to approximately 100-meter scale.

Main Results:

• Successfully resolved key mean source parameters for two Mw~4 earthquakes.
• Identified potential inaccuracies in standard seismic estimates.
• Inferred a power-law decay in stress and friction heterogeneity spectra.

Conclusions:

• The developed method offers high resolution for studying small earthquake ruptures.
• This approach can unravel previously elusive small-scale earthquake characteristics.
• Advanced dynamic inversions promise deeper insights into fault mechanics.