SCEC Award Number 18092 View PDF
Proposal Category Individual Proposal (Integration and Theory)
Proposal Title Multi Segment Fault Rupture Modeling and Strong Ground Motion Simulation Using Irikura, Japan Recipe. Implementation in the in SCEC BB Platform
Name Organization
Arben Pitarka Lawrence Livermore National Laboratory
Other Participants
SCEC Priorities 4c, 4a, 4d SCEC Groups GM, EEII, CME
Report Due Date 03/15/2019 Date Report Submitted 04/29/2019
Project Abstract
The project had two main objectives. The first objective was to complete the implementation of an earthquake rupture generator based on the method proposed by Irikura and Miyake (2011), also known as Irikura recipe (IM2011 method hereafter), in the BBP by extending its formulation to multi-segment rupture, and developing the software infrastructure. The second objective was to investigate the possibility of using the earthquake rupture generator as a standalone BBP rupture module that can be attached to other strong ground motion simulation methods already in use in the BBP. We successfully tested and validated the IM2011 multi-segment rupture generator in conjunction with Graves and Pitarka method (GP, hereafter) one of the BBP methods (e.g., Pitarka et al., 2017), and performed simulations of the M7.0 2016 Kumamoto, Japan earthquake (Pitarka et al., 2019).
IM2011 is the most popular method in Japan that is used to simulate strong ground motion from Japanese crustal earthquakes (ERC, 2016). In response to technical requirements of the BBP, we made Irikura’s rupture generator procedure compatible with multi-segment rupture modeling approach, currently being adopted by BBP. The recipe is now fully functional on the BBP. This project benefited from the collaboration of the PI with professor Kojiro Irikura of Aichi Institute of Technology, Japan, assistant professor Hiroe Miyake of University of Tokyo, head of the Japanese side of collaboration with SCEC, and Dr.Iwaki and Dr. Morikawa, researchers at NIED, during which we identified rupture parameters that needed to be adjusted and investigated.
Intellectual Merit The project’s objectives align well with SCEC research objectives, including the primary goal of refining physics-based simulation methodologies with implementation of the Broadband Simulation Platform. Exchanging earthquake rupture models with our Japanese colleagues, improving our simulation methods and using them in simulations of scenario earthquakes will provide insight into the uncertainties inherent in the specification of earthquake rupture models for forward simulations. The proposed work deals with one of the Basic Questions of Earthquake Science Q4: How do strong ground motions depend on the complexity and nonlinearities of dynamic earthquake systems? It specifically addresses the related research priorities:
- Incorporate new effects and features in the SCEC Broadband Platform such as multi­segment rupture
-Develop novel algorithms and implementation of more realistic models for earthquake simulation, particularly those that improve efficiency and accuracy or expand the class of problems that can be solved
These research priorities, and establishing confidence in simulation-based predictions, are the focus of this project. The results of the proposed research can be used in the Community Modeling Environment’s simulation platforms initiative as an organizational tool to develop scientific software and establish validation of ground motion simulations by providing a better understanding of the difference between simulation techniques.

Broader Impacts The project directly contributes to efforts under the Earthquake Engineering Implementation Interface (EEII) by promoting collaborations with researchers and practicing engineers in US and abroad.
The completed implementation of the Japanese method for simulating ground motion in the platform has improved the BBP’s capabilities, and increases BBP’s exposure to a larger number of users in Japan, including engineers and practitioners, who are interested in using the SCEC BBP in simulations of ground motion from earthquakes in US and Japan.
Exemplary Figure Figure 3. Comparison of goodness of fit plots of spectral acceleration computed on the SCEC BBP for Landers earthquake. We used 50 rupture scenarios obtained with the IM2011 single segment rupture generator (center panel), and IRIKURA1 multi-segment rupture generator, developed during this project.