SCEC Award Number 20019 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title New Multi Segment Earthquake Rupture Model by Combining Irikura, Japan Recipe and Graves&Pitarka Models. Implementation in the in SCEC BB Platform
Investigator(s)
Name Organization
Arben Pitarka Lawrence Livermore National Laboratory
Other Participants
SCEC Priorities 4c, 4a, 4d SCEC Groups GM, CXM
Report Due Date 03/15/2021 Date Report Submitted 05/09/2021
Project Abstract
 The characterization of earthquake rupture has been at the forefront of new developments in numerical methods for strong ground motion simulations of crustal and subduction zone earthquakes. Analyses of recent large earthquakes indicate that multi-scale earthquake rupture models that combine large-scale, large-slip features with smaller, but effective high-frequency seismic energy generation areas, better reproduce overall characteristics of ground motion on a broad frequency range. Hybrid schemes that include spatial correlations and interdependency of rupture parameters guided by rupture dynamics modeling offer significant advantages for use in broadband ground motion simulations. In response to requirement for continuous technical improvements of the BBP, we propose an hybrid standalone multi-segment rupture generator by merging the asperity based Irikura’s rupture model and the stochastic BP rupture model. The IM-BP model preserves the most robust features of the original techniques, such as asperity-based approach of the IM model, and correlated depth-dependent spatial variations of physics-based kinematic rupture parameters of the BP model. We tested the performance of GP-IM multi-segment rupture generator in simulations of the M6.5 2016 Norcia, Italy earthquake, using a physics-based deterministic approach in the frequency range 0-5 Hz. The proposed multi-segment kinematic rupture model and the physics based simulation methodology proved to be reliable in reproducing the recorded ground motion time histories and spectral amplitudes recorded during the M6.5 Norcia, Italy earthquake.
Intellectual Merit The proposed project contributes to improvement and integration of models for source generation and wave propagation into the Broadband Strong Ground Motion Simulation Platform (BBP).
In response to requirement for continuous technical improvements of the BBP, we created an hybrid standalone multi-segment rupture generator by merging the asperity based Irikura’s rupture model and the stochastic BP rupture model. The IM-BP model preserves the most robust features of the original techniques, such as asperity-based approach of the IM model,
Broader Impacts This project benefited from existing collaborations of the PI with professor Kojiro Irikura of Aichi Institute of Technology, Japan, and assistant professor Hiroe Miyake of University of Tokyo, head of the Japanese side of collaboration with SCEC, who have expressed strong interest in merging IM and GP into an hybrid model, and implementing the multi-segment IM-GP method in the SCEC BBP. The implementation of the IM-GP in the platform will improve the BBP’s capabilities, and increase BBP’s exposure to a larger number of users who are interested in using the SCEC BBP in simulations of ground motion from earthquakes in US and Japan.
Exemplary Figure Figure 2. Topography map showing the study area indicated by the red rectangle (top panel), and vertical cross sections of the 3D velocity model used in the simulations (bottom panels) along A-A’ and B-B’ lines, indicated on the map. The black star indicates the epicenter of the Norcia Mw6.5 30th October 2016 earthquake. The surface projection of the causative fault with its secondary fault segment is indicated by the black rectangles. Red triangles indicate the strong motion stations used in this study.
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Figure 3. Kinematic rupture model for the Mw6.5 Norcia earthquake adopted from Scognamiglio et al., (2018) using a hybrid approach (Pitarka et al., 2019) that combines deterministic slip patches with random perturbations using Graves and Pitarka (2016) method. Left panel shows the main fault rupture model, and the right panel shows the secondary fault model activated during the Norcia earthquake. Top panels: Slip distribution and rupture time contours at 2 s. Middle panels: rise time. Bottom panels: peak slip rate computed from the slip rate function low pass filtered at 4 Hz.
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