Wave front evolution in strongly heterogeneous layered media using the fast marching method

Rawlinson, Nicholas; Sambridge, Malcolm

doi:10.1111/j.1365-246x.2004.02153.x

Cited by 381 publications

(201 citation statements)

References 78 publications

(108 reference statements)

Supporting

Mentioning

200

Contrasting

Order By: Relevance

“…These devices are not only valuable in terms of efficiency and flexibility for inverting model parameters such as P-wave velocity distribution, but particularly powerful if we attempt the practice of real-time seismic tomography in future, that is, we investigate temporal variations in model. In addition to the merits of the Huygens' method discussed in, for example, Saito (2001) and Rawlinson and Sambridge (2004), we can compute the ray path and travel time from every grid point in model to a given station together, by collocating source and station. We had better compute them before a new event takes place for the updated velocity model at hand obtained by the travel-time data for all the events in the past.…”

Section: Discussionmentioning

confidence: 99%

Recursive travel-time inversion: A tool for real-time seismic tomography

2005

View full text Add to dashboard Cite

A new recursive inverse scheme is applied to a currently popular problem named seismic travel-time tomography, in order to enhance the efficiency and reliability in obtaining a new velocity model if a small number of new data are added to a large data set in the past. In comparison with conventional inverse schemes in seismic tomography, either least-squares or iterative types, this scheme does not require large amounts of matrix-type computations but utilizes the amount of modification in model parameters responsible for each new data set. We also introduce the computation of a collocation travel time (i.e., from a given station to every grid point) for the reference velocity model inverted by the data for all the past events, using a ray tracing scheme called the Huygens' method (Saito, 2001), suitable to computations prior to a new event. Combining the above information already stored with the recursive inverse scheme, we can obtain a new or updated velocity model immediately after a new event takes place, because a temporal interval between two events is usually very long in a given local area. Since the model is revised at each recursive step, we perform ray tracings with the updated reference model to get more accurate ray paths and travel times than the conventional inversion schemes that use all the ray tracings for the same reference model. We first showed the validity and stability of the proposed method with synthetic data. We then applied the new approach to the P-wave travel-time data recorded in the Hidaka, south-central Hokkaido, Japan, region, and compared our result with other previous results. Our result shares the overall feature with the previous ones. In addition, a new low-velocity zone is detected in the east of the Hidaka mountains at the depth of 10 km, corresponding to the collision zone of two arcs, due to the use of the updated reference velocity model at each recursive step. We also confirmed that the order of data does not affect the final result, so that the present approach is shown as an appropriate tool for so-called real-time seismic tomography: a updated velocity model is immediately obtained at each time that a new event takes place, in order to monitor temporal variations of model parameters such as velocity structure on the real-time basis.

show abstract

Section: Discussionmentioning

confidence: 99%

Recursive travel-time inversion: A tool for real-time seismic tomography

2005

View full text Add to dashboard Cite

show abstract

“…In addition to the flexible regularization based on ray densities, the method also deals with ray bending in an inhomogeneous medium, which was traced using the fast marching method (Rawlinson and Sambridge 2004). In the inversion scheme the partial derivatives of the group and phase velocities using S-wave velocity as a function of depth provide a sensitivity kernel for each period and produce velocity constraints on the depth dimension.…”

Section: Methodsmentioning

confidence: 99%

“…There are four main parts to the procedure: (1) preparing data for a single station, (2) extracting the empirical Green's function (EGF) for each station pair by cross-correlation, (3) measuring group and phase velocities as a function of frequency (Rayleigh wave dispersion) from the EGF, and (4) jointly inverting 3-D S-wave velocity models. For the inversion scheme we applied a fast marching method (Rawlinson and Sambridge 2004) for 2-D ray tracing to account for ray bending in an inhomogeneous medium. We provide detailed descriptions of each part of the procedure in the following sections.…”

Section: Methodsmentioning

confidence: 99%

South Ilan Plain High-Resolution 3-D S-Wave Velocity from Ambient Noise Tomography

Chen¹,

Chen²,

Chen³

et al. 2016

Terr. Atmos. Ocean. Sci.

View full text Add to dashboard Cite

The Ilan Plain in northeastern Taiwan is located at a pivotal point where the Ryukyu trench subduction zone, the northern Taiwan crustal stretching zone, and the ongoing arc-continent collision zone converge. In contrast to the North Ilan Plain, the South Ilan Plain exhibits a thin unconsolidated sedimentary layer with depths ranging from 0 -1 km, high on-land seismicity and significant SE movements relative to Penghu island. We deployed a dense network of 43 short-period vertical component Texan instruments from June to November 2013 in this study, covering most of the South Ilan Plain and its vicinity. We then used the ambient noise tomography method for simultaneous phase and group Rayleigh wave velocity measurements to invert a high-resolution 3-D S-wave for shallow structures (up to a depth of 2.5 km) in the South Ilan Plain. We used the fast marching method for ray tracing to deal with ray bending in an inhomogeneous medium. The resulting rays gradually bend toward high velocity zones with increasing number of iterations. The high velocity zone results are modified by more iterations and the resolutions become higher because ray crossings are proportional to ray densities for evenly distributed stations. The final results agreed well with known sedimentary basement thickness patterns. We observed nearly EW trending fast anomalies beneath the mountainous terrain abutting to the South Ilan Plain. The Chingshui location consistently exhibited a low S-wave velocity zone to a depth of 1.5 km.

show abstract

“…Then, we use the background traveltimes to compute the remaining coefficients, which consist of solving linear PDE (see Appendix A). We rely on the fast marching method to solve such equations (Sethian, 1996;Rawlinson and Sambridge, 2004). We show two examples that assess the accuracy of equation 10.…”

Section: Traveltime Approximation For Complex Orthorhombic Mediamentioning

confidence: 99%

Traveltime approximations and parameter estimation for orthorhombic media

Masmoudi

Alkhalifah

2016

GEOPHYSICS

View full text Add to dashboard Cite

Building anisotropy models is necessary for seismic modeling and imaging. However, anisotropy estimation is challenging due to the trade-off between inhomogeneity and anisotropy. Luckily, we can estimate the anisotropy parameters if we relate them analytically to traveltimes. Using perturbation theory, we have developed traveltime approximations for orthorhombic media as explicit functions of the anellipticity parameters η 1 , η 2 , and Δχ in inhomogeneous background media. The parameter Δχ is related to Tsvankin-Thomsen notation and ensures easier computation of traveltimes in the background model. Specifically, our expansion assumes an inhomogeneous ellipsoidal anisotropic background model, which can be obtained from well information and stacking velocity analysis. We have used the Shanks transform to enhance the accuracy of the formulas. A homogeneous medium simplification of the traveltime expansion provided a nonhyperbolic moveout description of the traveltime that was more accurate than other derived approximations. Moreover, the formulation provides a computationally efficient tool to solve the eikonal equation of an orthorhombic medium, without any constraints on the background model complexity. Although, the expansion is based on the factorized representation of the perturbation parameters, smooth variations of these parameters (represented as effective values) provides reasonable results. Thus, this formulation provides a mechanism to estimate the three effective parameters η 1 , η 2 , and Δχ. We have derived Dix-type formulas for orthorhombic medium to convert the effective parameters to their interval values.

show abstract

Wave front evolution in strongly heterogeneous layered media using the fast marching method

Cited by 381 publications

References 78 publications

Recursive travel-time inversion: A tool for real-time seismic tomography

Recursive travel-time inversion: A tool for real-time seismic tomography

South Ilan Plain High-Resolution 3-D S-Wave Velocity from Ambient Noise Tomography

Traveltime approximations and parameter estimation for orthorhombic media

Contact Info

Product

Resources

About