The 3D Reference Earth Model Project: Reconciled Data, Full-spectrum Tomography and Community Tools

Abstract:

Leveraging diverse constraints from traditionally siloed disciplines is critical for understanding global mantle dynamics and composition. Robust thermo-chemical inferences require self-consistent descriptions of bulk physical properties in terms of radial reference Earth models (e.g. PREM) and lateral heterogeneity in terms of three-dimensional tomographic models. Reference Earth models have proven indispensable in earthquake location, imaging of interior structure, understanding material properties under extreme conditions, and as a reference in other fields, such as particle physics and astronomy. We present features of a three-dimensional reference Earth model (REM3D) that capture the consensus view of long-wavelength heterogeneity in the mantle.

Progress in modeling the Earth’s interior is driven by diverse data, ranging from astronomic-geodetic constraints to full seismic waveforms and measurements of body waves (~1 – 20s), surface waves (~20 – 300s) and normal modes (~250 – 3000s). We construct a reference dataset by reconciling measurements contributed by several groups across the world from a plethora of techniques and approximations. We retrieve the missing metadata in several legacy compilations, archive in scalable storage formats, document outliers indicative of the limitations in some techniques, and quantify summary reference data with uncertainties. Full-spectrum tomography employs the reference datasets to constrain physical properties – seismic velocity, anisotropy, density, attenuation and the topography of discontinuities – in variable resolution. The parameterization is dictated by the inter-dataset consistency when inverting structure of various wavelengths and the uncertainties are systematically evaluated.

To increase utility for the deep Earth community, we have developed scalable model classes and storage formats with archival of metadata, web-applets for visualization and outlier analysis, data validation with benchmarked forward solvers accessible through application programming interfaces (APIs). As a community reference model with an associated publicly available dataset and tools, REM3D will facilitate Earth imaging studies, earthquake characterization, inferences on temperature and composition in the deep interior.