Impact of intermittent decorrelation events on InSAR time series, with application to the Salton Trough, CA

Rowena B. Lohman, & Junle Jiang

Submitted August 15, 2020, SCEC Contribution #10658, 2020 SCEC Annual Meeting Poster #111

InSAR time series in agricultural regions have long been recognized to be strongly affected by cultivation and vegetation growth. Variations in soil moisture and vegetation can negatively impact data quality and also can affect the interferometric phase. Researchers, therefore, must take care to not misinterpret these pseudo-deformation signals as being due to motion on faults or other subsurface sources. Recent research has also suggested that InSAR time series analyses can produce different results depending on the time span of the interferograms formed between the available dates. Inversions for deformation that only use the shortest time span interferograms (all those between adjacent image acquisition dates) tend to result in more spatially heterogeneous maps of average ground deformation rates than those that also include “redundant” interferograms that span longer time intervals (e.g., “skip-1”, “skip-2”, etc.). We show how this observation can result when there are time periods with lower data quality, potentially due to rain events, agricultural activity, etc., that are not explicitly accounted for in the analysis. We demonstrate this in the Laguna Salada region as well as in individual agricultural fields. These sorts of behaviors, which are only now becoming apparent as the SAR time series quality has improved, have large implications for how SAR time series should be interpreted in cases where there are even small gaps in the time series. Locations where the ground surface may be characterized by periods of constant deformation interrupted by periods of rapid change in the opposite sense (i.e., a “sawtooth”) that tend to be obscured by decorrelation should be carefully excluded from analyses that focus on the long-term rate.

Key Words
InSAR, Salton trough

Lohman, R. B., & Jiang, J. (2020, 08). Impact of intermittent decorrelation events on InSAR time series, with application to the Salton Trough, CA. Poster Presentation at 2020 SCEC Annual Meeting.

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