Validation and Testing of SALSA3D: A global model of compressional wave speed for the crust and mantle

Begnaud, M. L.; Ballard, Sanford; Hipp, James Richard; Encarnacao, Andre Villanova; Young, Christopher; Phillips, W. S.; Rowe, C. A.

doi:10.2172/1832358

Cited by 2 publications

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“…4) and allow variations with depth as opposed to legacy SSSCs. The 3DTTLS also include estimates of path-dependent uncertainty, which are critical to obtaining more accurate error ellipse sizes and orientations when used with location algorithms (Begnaud et al, 2020a(Begnaud et al, , 2021a) (Fig. 4).…”

Section: D Travel-time Lookup Surfaces (3dttls)mentioning

confidence: 99%

“…In order to compare location accuracy between full 3D ray tracing and the 3DTTLS, a set of 2279 events was selected from previous validation tests for the SALSA3D model (Begnaud et al, 2020a). These validation events have epicenters known to within 5 km or better [i.e., ground truth, GT5; Bonda ´r & McLaughlin, 2009;Bonda ´r et al, 2004)] (Fig.…”

Section: Accuracy Of 3dttls Versus 3d Ray Tracingmentioning

confidence: 99%

“…The speed of using these 1D models made them the preferred type of velocity model for operational needs, mainly due to computational requirements. Higher-dimensional seismic velocity models (e.g., three-dimensional (3D)) are becoming more readily available from the scientific community (e.g., Ballard et al, 2016a;Begnaud et al, 2020b;Hosseini et al, 2019;Li et al, 2008;Myers et al, 2010;Simmons et al, 2012) and can provide significantly more accurate event locations over 1D models (Begnaud et al, 2020a(Begnaud et al, , 2021a(Begnaud et al, , 2021bMyers et al, 2015). The computational requirements for full ray tracing using these higher-dimensional models tend to make their operational use prohibitive.…”

Section: Introductionmentioning

confidence: 99%

“…Figure 12Validation events (2279) for comparing location differences between SALSA3D with full 3D ray tracing and the 3DTTLS. All events have epicenters known to within 5 km or better (GT5)(Begnaud et al, 2020a) …”

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confidence: 99%

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Developing a Consistent Travel-Time Framework for Comparing Three-Dimensional Velocity Models for Seismic Location Accuracy

Begnaud

Davenport

Conley

et al. 2022

Pure Appl. Geophys.

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Location algorithms have historically relied on simple, one-dimensional (1D) velocity models for fast seismic event locations. 1D models are generally used as travel-time lookup tables, one for each seismic phase, with travel-times pre-calculated for event distance and depth. These travel-time lookup tables are extremely fast to use and this fast computational speed makes them the preferred type of velocity model for operational needs. Higher-dimensional (i.e., three-dimensional—3D) seismic velocity models are becoming readily available and provide more accurate event locations over 1D models. The computational requirements of these 3D models tend to make their operational use prohibitive. Additionally, comparing location accuracy for 3D seismic velocity models tends to be problematic, as each model is determined using different ray-tracing algorithms. Attempting to use a different algorithm than the one used to develop a model usually results in poor travel-time prediction. We demonstrate and test a framework to create first-P and first-S 3D travel-time correction surfaces using an open-source framework (PCalc + GeoTess, https://www.sandia.gov/salsa3d/software/geotess) that easily stores 3D travel-time and uncertainty data. This framework produces fast travel-time and uncertainty predictions and overcomes the ray-tracing algorithm hurdle because the lookup tables can be generated using the exact ray-tracing algorithm that is preferred for a model.

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Section: D Travel-time Lookup Surfaces (3dttls)mentioning

confidence: 99%

Section: Accuracy Of 3dttls Versus 3d Ray Tracingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Developing a Consistent Travel-Time Framework for Comparing Three-Dimensional Velocity Models for Seismic Location Accuracy

Begnaud

Davenport

Conley

et al. 2022

Pure Appl. Geophys.

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Seismic Tomographic Modeling of the Crust and Upper Mantle beneath Israel and the Middle East: Improved Resolution through Optimized Model Parameterization

Babikoff

Begnaud

Rowe

et al. 2022

Bulletin of the Seismological Society of America

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Accurate regional seismic travel-time (RSTT) predictions rely on regional phases (e.g., Pg, Lg, Pn, Sn) to account for 3D effects in the crust and upper mantle that are not captured by 1D models traditionally used for real-time location. The RSTT prediction model accounts for regional-scale crust and upper mantle structure globally by incorporating regional seismic phases into its travel-time calculations. Previous versions of the RSTT model have used a constant grid cell size of 1°. To improve the tomographic accuracy of recovering velocity structure at regional scales, we perform data-driven grid refinement on the RSTT model down to a 0.125° grid (∼14 km) in pursuit of two main goals: (1) to test the limits of RSTT capability and accuracy of determined velocity structure through variable grid refinement and (2) to image smaller structures in Israel and the Middle East and illuminate upper mantle dynamics operating in this complex tectonic area. We investigate the effects of model parameterization as grid cell size decreases and the trade-offs between recovered velocity structures. Our final dataset includes 4751 events and 499 stations that recorded 79,344 Pn and 7489 Pg. The variable grid refinement method allows recovery of finer-scale velocity structures and reduces travel-time residuals in areas with the highest data coverage. At smaller grid cell sizes, longer paths need to be upweighted to stabilize the inversion. Results illuminate tectonic features undefined in coarser grid-size models; in particular, we observe mantle perturbations related to the subduction zone around the Cyprian arc and crustal anomalies near the Dead Sea fault and throughout the Anatolian plate.

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Validation and Testing of SALSA3D: A global model of compressional wave speed for the crust and mantle

Cited by 2 publications

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Developing a Consistent Travel-Time Framework for Comparing Three-Dimensional Velocity Models for Seismic Location Accuracy

Developing a Consistent Travel-Time Framework for Comparing Three-Dimensional Velocity Models for Seismic Location Accuracy

Seismic Tomographic Modeling of the Crust and Upper Mantle beneath Israel and the Middle East: Improved Resolution through Optimized Model Parameterization

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