PI proposed a phase space ray tracing algorithm which is beyond the conventional approach using kinematic first arrival seismic ray tracing algorithm for studies involving modeling and reconstructing smoothly varying solution (tomography). Application of high frequency, high resolution phase space ray tracing for seismic problem has the advantages of multi-sources, multi-valued arrivals for complex media. Such proposed approach is suitable for simulating diffraction phenomena involving multi-scattering and paths. For 3D ray tracing in complex structure media, solution is operate in 6D phase space and has the advantages that the characteristic curves are all smoothly varying and single valued. Therefore, multi-valued travel-times, ray paths, wavefronts, and dynamic properties of amplitude and phase for simulating diffraction phenomena can be properly handled. The explicit Eulerian scheme which capable of simultaneously solving "factored" first order ordinary differential Helmholtz equations with givenmultiple initial values and through Runge-Kutta-Fehlberg predictor-corrector algorithm. Key methods involved are model building through AMR and RKF45 numerical integration. AMR is designed for model geometry construction purpose. RKF45 is a method of control computational local and cumulative errors with accuracy of order O(h4) and with an error estimator of order O(h5). The error can be estimated and controlled by using high-order embedded method that allow for automatically determine the adaptive step size and direction when solution become ill-posed. The seismic properties involved will not simply focus on kinetic issues covering travel-time, ray path, wave front tracking but rather emphasis on its dynamic properties associate with amplitude/phase/force/moment/energy. Proposed method not only capable of simulating responses for isotropic media but also anisotropic material. PI revealed past experiences on computing synthetic dynamic seismic responses (seismograms), propose new approach and direction to over-come limitations. Current progress on a self-developed hybrid method through travel-time computation joint with wavefield inversion approach can be applied to both marine multi-channel seismic data (MCS) and OBS (ocean bottom seismograph) dataset. Application to TAIGER T4B and T6 transect lines are just completed. Apaper on methodology is submitted for review. Application to TAIGER active experiments for T4b and T6 lines are under preparation. Continue effort involved is to study N-S transects lines across central mountain and east longitudinal valley areas. Dynamic simulation on amplitude and phase for high frequency responses through Halmilton-Jacobi Theory will be further developed, test, implemented for Q tomography and possibly on anisotropy studies. PI alsodemonstrated the initial study result on dynamic crack/rupture front propagation simulation over a crack surface through proposed phase field ray tracing approach. Potential applications on practical problems are demonstrated including dynamic rupture front simulation, illumination analysis for seismic network, under going research on scattering and intrinsic attenuation estimation and self-developed hybrid travel-time and wavefield inverion. Therefore, PI's proposal on its front-end researches and its potential practical applications which demonstrated in PI's proposal becomes fairly apparent.
|Effective start/end date
|1/08/21 → 31/07/22
UN Sustainable Development Goals
In 2015, UN member states agreed to 17 global Sustainable Development Goals (SDGs) to end poverty, protect the planet and ensure prosperity for all. This project contributes towards the following SDG(s):
- High frequency
- High resolution
- Phase space
- Ray Tracing
- Digital model building
- Active and passive source seismic data
- Complex media
- Practical application
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