Impact of solutions on the identification of tectonic transients: A case study using the last decade of GNSS data in South America

GNSS derived displacement time series are used to track plate tectonics and the associated motions across major plate boundaries. With a growing number of continuous GNSS observations, it is becoming increasingly apparent that plate trajectories rarely conform to standard trajectory models. The deviations from these expected trajectories can be considered as transient motions, some being tectonically related, and others being related to geophysical fluid loading, local site effects, and artifacts of the GNSS processing. As we increasingly inspect the transient motions of GNSS displacement time series, we have to take care that the GNSS processing choices, such as the reference frame, are not introducing non-tectonically related artifacts into the eventual isolated tectonic signals.

Here we explore the effects that different solutions and processing strategies have on our eventual daily GNSS displacement time series - the aim being to explain how artifacts arise and to determine which strategies best mitigate these artifacts. We compare displacement time series made from both Precise Point Positioning and network (double-differenced) solutions that are provided in the latest official reference frame solution ITRF2014, and in JTRF2014 based on Kalman filtering.

In our analyses, we use approximately one hundred GNSS stations from South America, with a focus being to identify transient tectonic activity related to the subduction of the Nazca plate under Chile over the past decade.