Earthquake Stress Drops From Dynamic Rupture Simulations Constrained by Observed Ground Motions
František Gallovič, Ľubica Valentová
Abstract
Abstract Stress drop characterizing dynamics of earthquake rupture propagation has various definitions and measures with a yet unclear mutual relationship. We aim to reconcile this discrepancy by analyzing synthetic dynamic rupture models generated by random sampling of the model space of spatially heterogeneous dynamic rupture parameters. An ensemble of ~1,600 dynamic models, with waveforms statistically fitting empirical Ground Motion Prediction Equations, is treated as a synthetic event database. The events exhibit various magnitudes, degrees of complexity, and realistic ω −2 spectral decay of their average moment rates. While the variability of the stress drop Δτ e estimated from the moment rates agrees with real data studies ( , the true static stress drops Δτ s evaluated directly from the dynamic models exhibit larger values and lower variability ( ). Our study suggests that the disagreement between various stress drop definitions is related to the source model approximation and not to any particular data processing.