Earth's outermost layer, the crust, comprises a critical zone that participates in and controls processes of Earth's deep interior as well as in the atmosphere. Variations in crustal rocks influence Earth's magnetic field as well as gravity. A good model of Earth's crust is therefore essential to understand a wide range of applications including improved seismic imaging of Earth's mantle, understanding the causes of Earth's topography and Earth dynamics, defining the chemical make-up of Earth's crust and the recycling of these materials into the mantle through plate tectonics, and ultimately understanding the linkage and interaction of Earth's crust with its atmosphere processes. Last year, the PI released CRUST1.0, a global model that is based on a large new database of seismic data. In the past, the crustal models were used primarily by academic investigators and their students, who are typically located at universities or research institutions. But now there is an increasing traffic from non-university locations, with an increasing interest from the industry. A growing fraction of users appears to rely on a diverse set of computer programs to read and work with the model. To respond the demands a web-based support will be provided. At the same time, the model will be continuously improved by carefully testing it against data collected in the field and making modifications when necessary. This grant funds efforts to facilitate a wider circulation of the evolving model through improved computer tools to read and visualize the model.
Global crustal model CRUST1.0 saw its release to the community earlier this year, after several years of compiling and updating active and passive seismic databases on crustal structure, and initial model validation against surface wave data. This highly anticipated model replaces CRUST2.0 which has served as the "benchmark crustal model" for over ten years in a diverse, interdisciplinary community. CRUST2.0 was originally compiled to apply crustal corrections in whole-mantle tomographic studies, in an era and area of academia where Fortran computer code was the most widely used and understood tool to work with. CRUST1.0 has a simpler, new file structure, and similar Fortran codes are provided to un-pack the model. However, since its short existence as an open-source model, requests have been overwhelming to provide more modern and "user-friendly" tools to work with CRUST1.0. This grant helps design and provide such tools. At the same time, user feedback will be responded to improve CRUST1.0 following a through validation process. During Phase 1 of the proposed work, user requests will be responded to provide the model in various file formats, including xyz files, binary grd files and ArcGIS files. Reading and visualization tools will be developed for CRUST1.0 for a variety of platforms such as c-shell scripts, Python, Matlab, GMT and ArcGIS. By providing the proposed tools, CRUST1.0 will have a much wider reach than CRUST2.0 ever had. During Phase 2, enhanced model validation will be performed using existing crustal databases. Work during this phase will be used to employ and educate undergraduate students. During Phase 3, user feedback as well as new constraints from surface waves will be iteratively incorporated. The release of an update of CRUST1.0 is anticipated that will have an improved consistency with active seismic as well as passive seismic datasets.
