SCEC Award Number 21002 View PDF
Proposal Category Individual Proposal (Data Gathering and Products)
Proposal Title An open source code for 3-D measurement of ground deformation from optical image correlation
Investigator(s)
Name Organization
Jean-Philippe Avouac California Institute of Technology
Other Participants Dr. Chris Milliner
Dr. Saif Aati
SCEC Priorities 2c, 2d, 2e SCEC Groups Geology, Geodesy
Report Due Date 03/15/2022 Date Report Submitted 03/22/2022
Project Abstract
 We developed and implemented a new method to extract high-quality surface displacement in 3D using multi-date and multi-platform high resolution (HR) optical imagery. The workflow uses the upgraded open-source software COSI-Corr+. The software allows: data preprocessing, image geometry (RSM) optimization, orthorectification, sub-pixel image correlation, 3D-displacement computation. We used the case-example of the ground deformation caused by the Ridgecrest earthquake sequence to assess the performance of our proposed approach. We were able to generate high quality measurements of coseismic ground displacement with GSD of 2.4m, and uncertainties at the 90% confidence level on the NS, EW and vertical displacement measurements of 0.6m, 0.7m, and 0.6m respectively (see exemplary Figure). An article presenting the technique has been submitted [Aati, Milliner and Avouac, RSE, in review]. A follow up article focused on the 2019 Ridgecrest earthquake is presenting how these measurement can be used to constrain spatial variations of stress and fault friction (static and dynamic) [Milliner, Aati and Avouac, JGR, submitted].
Intellectual Merit The technique developed under this project allows making improved and automated measurements of surface deformation caused by earthquakes using optical images. These measurements are essential to investigate earthquake physics in complement to seismological, geodetic and field studies. The originality of the techniques lies in the procedure to disentangle stereoscopic effects from ground displacements in the offset measurements.
Broader Impacts COSI-Corr+ is an open source software which, as its parent software
COSI-Corr, can be used for a wide range of applications in Earth Sciences. It makes it easier to take advantage of the wealth of optical data now available and can be used in remote sensing classes at the undergraduate level.
Exemplary Figure Figure 1: Reference 3D-ground displacement field due to the Mw7.1, Ridgecrest earthquake of July 4th, 2019, measured from multi-platform high resolution satellite images using COSI-Corr++ open-source software. (a-c) Color maps representing the East/West, North/South, and vertical ground displacement, respectively. (d-f) Profiles extracted along the respective black box in panels (a-c). From Aati, Avouac and Milliner [RSE, in review].