- Related Research Areas
- Earth Surface & Interior
Accurate measurements of deformation of the Earth's crust are essential for studies of the seismic cycle, strain transfer, migration of magmatic and hydrous fluids in the crust and mantle, plate boundary processes, and large-scale continental deformation. The EarthScope Program of NSF, NASA, and USGS is providing increasingly large volumes of space geodetic data that may yield valuable insights into these deformation phenomena. In particular, the Plate Boundary Observatory (PBO) is generating point measurements of surface displacements and strains from a dense network of GPS stations and strainmeters in the Western US. The GeoEarthScope initiative is providing Interferomeric Synthetic Aperture Radar (InSAR) data from a number of currently active space-borne missions, including ERS-2, ENVISAT, RADARSAT, and ALOS. Dramatic increases in the amount of space geodetic data allow one to reduce uncertainties in measurements of subtle deformation, for example, due to secular tectonic loading, inteseismic bild-up of strain on seismogenic faults, postseismic trainsients, and anthropogenic activity. Major limiting factors of InSAR measurements of slow deformation are (i) atmospheric noise and (ii) sensitivity to the line-of-sight component of surface displacements. The focus of this proposal is development of computationally efficient techniques for processing, analysis and reduction of large volumes of InSAR data, and application of these techniques to study secular and transient deformation in seismically and tectonically active areas of the North America-Pacific plate boundary. In particular, we will develop a scheme for estimating the magnitude of atmospheric noise by exploiting the redundancy of InSAR acquisitions. The inferred measure of atmospheric contributions will then be used to construct an optimal stack of interferograms maximizing the signal-to-noise ratio of a mean velocity field. We also propose to implement and evaluate stacking of along-track interferograms to obtain an extra component of the velocity vector that is orthogonal to the radar line of sight. The proposal research is directly relevant to the "EarthScope: The InSAR and Geodetic imaging Component" Focus Area of ROSES, as well as to NSAS's Science Questions and Research Objectives. In particular, the proposed work relies on the use of the remote sensing data to address the following overarching questions: How is the Earth's surface being transformed by naturally occurring tectonic processes? What are the motions of the Earth's interior, and how do they directly impact our environment? and How can our knowledge of Earth surface change be used to predict and mitigate natural hazards? Results of our data analysis will be used to addres a number of outstanding questions, including the mechanisms and time scales of stress and strain transfer in the seismogenic crust, relationship between geologic and geodetic slip rates on major seismogenic faults, and time-dependent response of the Earth crust and mantle to large earthquakes. Well-constrained observations of the post-seismic and inter-seismic deformation will be relevant to the on-going debate about the effective mechanical thickness and strength of the tectonicall active continental crust.
Project PI: Yuri Fialko/University of California San Diego
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