Join us in Vancouver in October 2023 for a new SSA conference on regionalized, empirical and physics-based ground motion modeling, co-sponsored with the Seismological Society of Japan. We’re looking forward to sharing new research and fostering a lively discussion about the ways the field is expanding.
Detailed Program View Schedule*Please note: The program is subject to change and may not reflect the most up to date information.
Co-chairs:
Annemarie Baltay, U.S. Geological Survey
Hiroshi Kawase, Kyoto University
Modern ground-motion modeling for improved source physics and hazard uses both simulations and empirical data for quantitative prediction of ground motions. Ergodic models that grouped similar tectonic regions around the world to make use of large data sets now share the field with spatially varying models which harness the knowledge from ergodic models but are specific to a region. At the same time, physics-based simulations that have often focused on a single region, fault or earthquake are now broadening their application to regions or faults not previously considered.
These converging trends make it important to share emerging technologies and different perspectives on how these models are built, and how they might be applied across a global community.
Confirmed featured keynote speakers include:
- Fabrice Cotton, GFZ German Research Centre for Geosciences
- Alice-Agnes Gabriel, Scripps Institution of Oceanography, University of California, San Diego
- Christine A. Goulet, U.S. Geological Survey, Southern California Earthquake Center
- Robert Graves, U.S. Geological Survey
- Shinichi Matsushima, Disaster Prevention Research Institute, Kyoto University
- David B. McCallen, Lawrence Berkeley National Laboratory, University of Nevada
- Hiroe Miyake, Earthquake Research Institute, University of Tokyo
- Marco Pilz, GFZ German Research Centre for Geosciences
The content will be organized broadly in the following topic areas:
Complex Kinematic Source Modeling
Understanding the complex source process during an earthquake has long been a target of earthquake scientists and engineers, since the establishment of homogeneous rectangular fault modeling. Complex kinematic source modeling through the inversion of observed ground motions over wide frequency ranges and spatial resolutions—from several seconds on the scale of tens of kilometers to several Hz on the order of a few hundred meters—allows us to infer the earthquake rupture and then forward propagate again ground motions. Varying kinematic representations of the source, such as size, shape and variability of the rupture patch, slip distribution and source time function, as well as the velocity structure of the model domain, can be validating through comparison to observed ground motion, and give us insight into plausible rupture dynamics. In this session we look at kinematic source inversions with novel parameterizations, complex source characterization, and the development of modeling techniques for ground motion simulation of future earthquakes.
Dynamic Rupture Propagation Analysis
While the basic concept of dynamic rupture simulation has been well established, due to increased computational power and spatially complex parameterization, we can generate ever more complex and realistic ground motions. Dynamic modeling allows for feedback of the behavior of the earthquake itself, dependent on initial conditions on the fault, material properties including velocity and elasticity, and relations between spatial/temporal stresses and slip. However, there are still outstanding issues for dynamic modeling, such as correlation between kinematic and dynamic parameters of the fault; validation of ground motions, source parameters and slip velocity as output, and consideration of different input relations such as dependency of stress drop on depth, elasticity, and friction laws. This session focuses on the recent progress on dynamic rupture propagation analysis for realistic ground motion simulations over a wide frequency range, considering complex input and output validation.
Regional Differences in Quantification of Path Effects
Path effects play an important role in both simulations and empirical modeling, especially over various spatial scales. For example, similarity and variations of attenuation have been observed between regions on both a small scale (tens of kilometers) and a large scale (hundreds of kilometers). The empirical measuring of path effects is fraught with tradeoffs, and it is important to understand how reliable they are. Of particular importance is the applicability of path effects established in one region to other regions with different tectonic setting. Thus, we focus this session on methods for estimating the path and the variability of path effects in different regions on various scales globally, as well as discussion of methodological differences in estimating path effects.
Physical Modeling Issues of Site Effects
Early numerical modeling of site effects included one-dimensional stacked layers, representing only body waves in the upper crust and sedimentary basin. However, many advances using two- and three-dimensional structure are better able to reproduce both the spatial complexity of ground motion, and particularly the observed long durations of motions. For physics-based site effect evaluation, we need both a complex velocity structure and observed ground motion records at the target site for model calibration. We invite submissions discussing a variety of methods for physical modeling of site effects and their accuracy.
Empirical Modeling of Site Effects
Empirical, observationally driven estimates of site amplification or attenuation can be more accurate than physics- and parameter-based methods. Separation of the site effects from observed seismic motions and subsequent modeling of site effects has been a major target in this field of research. Because of the complexity of geology and velocity around target sites, many features and parameters are challenging to model, such as 3D basin effects, high frequency response, spatial variations and azimuthally dependent effects. This session focuses on techniques and novel methods for describing site effects that improve our ability to characterize ground motion in regionalized and non-ergodic ways, and applying complex models into hazard analysis.
Empirically Modeling Source Effects as Inputs to Models
Determining a data driven source model of slip, rise time, stress, and other source parameters that can replicate the observed ground motion in a forward manner is key to accurately connecting our physical understanding of the genesis of strong ground motion. However, determination of these source models is still an underdefined problem and portraying that accurately in simulations in a manner that can be extrapolated is still challenging. Also, it is necessary to have the quantitative formula for source scaling based on the empirical evidence. This session focuses on new advances in both source characterization as well as the synthesis of the source models into ground motion models and simulations.
Challenges for Model Extrapolations Outside of the Data Range
While our ground motion datasets have increased and modeling powers have improved, and our interpolation abilities within model domains are excellent, difficulty still arises in extrapolating existing, verified models and techniques to domains outside of our data, such as very near-source, large magnitude events, or new regions that are currently seismically quiet—ranges that are arguably the most important for hazard modeling. Both emerging technologies and increased physical understanding, along with validated simulation capabilities, can move this forward. This session focuses on novel ways to bring existing methods and datasets together, as well as novel approaches to ensure that we are accurately representing important model domains.
Overall Prediction Accuracy and Simulation Validation For Real-World Applications
Simulated earthquake ground motions are often used to fill in gaps in the instrumental record by considering anticipated future earthquakes or past earthquakes for which we have relatively few, if any, recordings. A variety of methods can be used to generate synthetic ground motions, from stochastic methods for 1D Earth structure to deterministic methods using 3D Earth structure. In this wrap-up session, we invite presentations focused on comprehensive ground motion simulations and validation for future damaging earthquakes with applications from around the world. In such simulation projects, validation and extrapolation against empirical data is critical, with the methods of accuracy measurement also a target of discussion. This session will be geared towards the outlook of the community, and as such we invite both presenters and participants to discuss various applications and future directions.
Meeting Contact: abstracts@seismosoc.org