Lowering the Access Threshold to 3-dimensional Visualization and Programming Benchmarks via an Interactive Web Tool: Tensor Visualization Guide (TVguide) for Elasticity Tensor and Seismic Anisotropy Analysis

Abstract:

Elasticity tensors and seismic anisotropy are topics that tie together multiple subfields in Earth Sciences, such as mineralogy, geodynamics, rock physics, structural geology, and seismology. Analyzing and manipulating elastic tensors is in principle straightforward and can be done with existing software packages. At the same time, elasticity tensors and seismic anisotropy are notoriously non-intuitive for students and experts. Simple tasks such as plotting and rotating velocity stereonets can have pitfalls even for the advanced user and have a particularly high entry threshold for students. Typical barriers are problems with units and coordinate system orientation and the need to install dedicated software. Other difficulties include how to relate rock-based full elasticity tensors to simplifying assumptions made in seismological analysis, and how to interpret results in terms of seismic observables.

We present a web tool under development with funding from NSF Geoinformatics named the Tensor Visualization guide (TVguide) that is targeted towards lowering this access threshold. The web-based tool does not require installation. Users select from a provided set of rock-based elastic tensors or paste in their own. Stereonets of seismic velocities and associated properties such as shear wave splitting and surface wave azimuthal variations are plotted in 3-dimensional (3-D) views that can be rotated interactively via click and grab, aiding spatial thinking and understanding. A set of 2-D views can be compared (as a simple sanity and orientation check) to those from more customizable packages that require installation and coding. The tool contains a tensor decomposition and displays of isotropic, hexagonal, and lower symmetry components. It also calculates and displays average tensors for fold geometries. Students can use the web tool as an easily applied benchmark check as they learn to program within more customizable software packages containing similar functions. Our project includes user workshops at conferences to demonstrate the utility of TVguide to the community. We will also develop a module for use in undergraduate geophysics courses that is designed to make a fundamentally straightforward but technically complex topic accessible to interaction and experimentation.