Source Scaling of Simulated Dynamic Ruptures Using Hierarchical Slip-Weakening Patch Model

ABSTRACT In seismic hazard assessment, generating a source rupture process consistent with the physics of natural earthquakes is an important issue. This study focuses on the source model with hierarchical patches of slip-weakening distance Dc proposed by Ide and Aochi (2005), which can satisfy the Gutenberg–Richter law. To investigate how the model works, characteristics of the simulated dynamic rupture process in a homogeneous full-space medium and for a vertical strike-slip fault in a half-space medium with a seismogenic zone are analyzed, considering varying dynamic rupture parameters. The source spectrum of the simulated rupture process using the hierarchical patch model generally follows the Brune model. However, the source spectrum underestimates the Brune model near the corner frequencies when the event size grows over Mw 5.5. This spectral shape is consistent with the JA19_2 model (Ji and Archuleta, 2021) of the double-corner-frequency source spectrum. The obtained relationship between the simulated rupture length and magnitude is consistent with the empirical model of Leonard (2010). It confirms that if the event ruptures over the whole seismogenic zone width, the rupture length does not scale linearly with the rupture width, indicating that the seismogenic zone contributes to the relationship between rupture length and magnitude.