Toward the 3-component time-dependent Crustal Motion Model: Integration of Sentinel-1 SAR interferometry and continuous GPS

Ekaterina Tymofyeyeva, & Yuri Fialko

Published August 14, 2017, SCEC Contribution #7681, 2017 SCEC Annual Meeting Poster #105

We combined data collected between 2014-2017 by the Sentinel-1 InSAR mission with continuous GPS measurements to calculate the three components of the interseismic surface velocity field in Southern California at the resolution of InSAR data (~100 m). We used data from five Sentinel-1 tracks covering Southern California (descending tracks 71, 173, and 144, and ascending tracks 64 and 166). We processed a set of sequential interferograms for every track using GMTSAR, and applied the Bivariate Enhanced Spectral Diversity correction to mitigate errors in burst alignment. We used overlapping InSAR tracks with two different look geometries (corresponding to ascending and descending orbits) to obtain the 3 orthogonal components of surface motion. Because of the under-determined nature of the problem, we used the local azimuth of the horizontal velocity vector as an additional constraint. The spatially variable azimuths of the horizontal velocity were obtained by interpolating data from the continuous GPS network. We estimated both secular velocities and displacement time series. The latter were calculated by combining InSAR time series from different lines of sight with time-dependent azimuths computed using continuous GPS time series at every InSAR epoch. We used CANDIS method [Tymofyeyeva and Fialko, 2015], a technique based on iterative common scene stacking, to correct the InSAR data for tropospheric and ionospheric artifacts when calculating secular velocities and time series, and to isolate low-amplitude deformation signals in our study region. The resulting horizontal (East and North) components of secular velocity exhibit long-wavelength patterns consistent with strain accumulation on major faults of the Pacific-North America plate boundary. The vertical component of velocity reveals a number of localized uplift and subsidence anomalies, most likely related to hydrologic effects and anthropogenic activity. In particular, in the Los Angeles basin we observe localized uplift of about 10-15mm/yr near Anaheim, Long Beach, and Redondo Beach, as well as areas of rapid subsidence near Irvine and Santa Monica, which are likely caused by the injection of water in the oil fields, and the pumping and recharge cycles of the aquifers in the basin. Our three-component, time-dependent description of surface deformation from a combination of geodetic data sets can be used to enhance the SCEC Community Geodetic Model.

Citation
Tymofyeyeva, E., & Fialko, Y. (2017, 08). Toward the 3-component time-dependent Crustal Motion Model: Integration of Sentinel-1 SAR interferometry and continuous GPS. Poster Presentation at 2017 SCEC Annual Meeting.

Related Projects & Working Groups
Tectonic Geodesy