Time-dependent strain rate field for California from inversion of geodetic data
Kaj M. JohnsonSubmitted August 30, 2026, SCEC Contribution #15550, 2026 SCEC Annual Meeting Poster #063
GNSS and InSAR time series data provide increasingly detailed records of transient crustal deformation, but converting spatially irregular and noisy station time series into temporally resolved strain-rate fields remains challenging. For this purpose, I have developed BforStrain-TD, a time-dependent extension of the BforStrain method that estimates spatially distributed deformation and strain-rate changes directly from horizontal displacement time series. The method represents regional deformation using body-force sources distributed over a triangular mesh. Elastic Green’s functions relate these sources to displacement, velocity, strain, and rotation throughout the study region.
BforStrain-TD first uses all available geodetic data to estimate and remove a nominal steady velocity field from each station time series. It then performs a sequential inversion over successive observation intervals to recover transient body-force distributions and the resulting incremental strain-rate fields. Spatial regularization suppresses poorly resolved short-wavelength structure, while temporal regularization encourages physically reasonable evolution between adjacent intervals. Station-local benchmark parameters, represented as random walks, absorb site-specific monument motion and other incoherent signals that might otherwise map into the regional strain field. The inversion can accommodate changing station availability, missing observations, variable uncertainties, and optional constraints from creeping faults. Annual and semiannual signals may also be estimated and removed from the recovered body-force histories.
The steady-velocity/strain-rate field can be combined with the transient perturbations to produce total time-dependent strain-rate histories. Outputs include modeled and residual station displacements, cumulative deformation, body-force histories, and maps of incremental, background, and total strain rate. I will present some preliminary transient strain rate maps using GNSS time series data.
Key Words
strain rate, time-dependent deformation, GNSS
Citation
Johnson, K. M. (2026, 08). Time-dependent strain rate field for California from inversion of geodetic data. Poster Presentation at 2026 SCEC Annual Meeting.
Related Projects & Working Groups
Tectonic Geodesy
