ALOS-2 Time Series of Long-wavelength Deformation near the Mendocino Triple Junction

Abstract:

We seek to separate contributions from interseismic deformation associated with plate-boundary faults and those from potential geodynamic processes around the Mendocino Triple Junction. Here, we present a velocity map of Northern California generated using ALOS-2 InSAR data for the period 2015--2020. The removal of spatially heterogeneous ionospheric delays, estimated using the beam-splitting technique of Liang et. al. (2018) as implemented in ISCE, reduced residual noise, improving the accuracy of geodetic velocities. The velocity maps were integrated with GNSS data by removing the best-fitting plane between the LOS projected GNSS velocities and those derived from the InSAR data. The extended data collection period, the larger spatial extent of InSAR frames, and the implementation of new ionosphere-correction methods increase the capacity to observe vertical crustal deformation patterns spanning 100's of km. We investigate whether our results present evidence of contributions from geodynamic scale processes, in addition to fault-related deformation. For example, do the observed InSAR and GNSS velocities support the proposed crustal conveyor geodynamic model for the migrating Mendocino Triple Junction?