A geodetic software analysis tool enables the user to analyze 2D crustal strain from geodetic ground motion, and create models of crustal deformation using a graphical interface. Users can use any geodetic measurements of ground motion and derive the 2D crustal strain interactively. This software also provides a forward-modeling tool that calculates a geodetic velocity and strain field for a given fault model, and lets the user compare the modeled strain field with the strain field obtained from the user’s data.
Users may change parameters “on-the-fly” and obtain a real-time recalculation of the resulting strain field. Four data products are computed: maximum shear, dilatation, shear angle, and principal components. The current view and data dependencies are processed first. The remaining data products and views are then computed in a round-robin fashion to anticipate view changes. When an analysis or display parameter is changed, the affected data products and views are invalidated and progressively re-displayed as available.
This software is designed to facilitate the derivation of the strain fields from the GPS and strain meter data that sample it to facilitate the understanding of the strengths and weaknesses of the strain field derivation from continuous GPS (CGPS) and other geodetic data from a variety of tectonic settings, to converge on the “best practices” strain derivation strategy for the Solid Earth Science ESDR System (SESES) project given the CGPS station distribution in the western U.S., and to provide SESES users with a scientific and educational tool to explore the strain field on their own with user-defined parameters.
This work was done by Sharon Kedar, Sean C. Baxter, Jay W. Parker, Frank H. Webb, Susan E. Owen, Anthony J. Sibthorpe, and Danan Dong of Caltech for NASA’s Jet Propulsion Laboratory.
This software is available for commercial licensing. Please contact Daniel Broderick of the California Institute of Technology at
This Brief includes a Technical Support Package (TSP).
Geodetic Strain Analysis Tool
(reference NPO-47504) is currently available for download from the TSP library.
Don't have an account?
Overview
The document discusses advancements in geodetic strain analysis, particularly focusing on the limitations of strain estimation techniques derived from sparsely sampled geodetic observations. It highlights the significant progress made over the past decade in geodetic networks, which have accumulated sufficient data to analyze aseismic strain accumulation in tectonically active areas. As GPS networks become denser, they allow for increased spatial resolution in derived strain fields, revealing intricate details that necessitate careful examination.
The analysis emphasizes the variations in strain accumulation rates across major fault zones, such as the San Andreas Fault Zone, where discrepancies in shear and dilatation values arise from different strain estimation methods. The document identifies two primary classes of techniques used for strain estimation:
- Direct Estimation: This method calculates strain directly from deformation measurements, traditionally applied to geodetic campaign data.
- Interpolation of Velocity Fields: This approach involves interpolating the velocity field (with varying assumptions about the tectonic setting) and then calculating strain from the continuous derivatives of the interpolated vector field.
The document explores the limitations of these techniques through an interactive Strain Analysis Tool, which allows users to investigate the effects of grid sampling and network orientation relative to the deformation field. It discusses how apparent artifacts in the strain field can depend on these factors, providing insights into the complexities of accurately estimating strain in real-world tectonic settings.
The findings underscore the importance of understanding the underlying mathematical techniques and their implications for strain analysis. The document concludes by encouraging further exploration of these effects in realistic tectonic environments and GPS station distributions, emphasizing the need for continued refinement of strain estimation methods.
For additional information, the document provides contact details for the Jet Propulsion Laboratory (JPL) and highlights the broader technological, scientific, and commercial applications of the research. It also includes a notice regarding the liability and endorsement of the information presented, reinforcing the commitment of NASA to share aerospace-related developments with wider audiences. Overall, the document serves as a valuable resource for researchers and practitioners in the field of geodesy and tectonics.
