Estimation of Time-Dependent Strain-Rates with Gaussian Process Regression

Session: Crustal Stress and Strain and Implications for Fault Interaction and Slip
Type: Oral
Date: 4/28/2020
Time: 11:45 AM
Room: 240
Description: 

We recently proposed a method, PyGeoNS (Python-based Geodetic Network Smoother), to determine spatiotemporally continuous maps of time-varying strain-rates from GPS/GNSS measurements. The resolved strain-rates have robustly quantified uncertainties and include discontinuities in surface displacements across fault segments with potential creep. PyGeoNS inverts the full GPS/GNSS displacement time-series using Gaussian process regression (GPR). GPR is a non-parametric, Bayesian method which interpolates the GPS/GNSS data in both space and time, assuming a stochastic prior model for displacements. The prior is on the covariance structure of the interpolated field, which effectively constrains the minimum wavelength of spatial variation of strain-rates, along with the degree to which transient displacements are allowed. By varying the prior one can determine strain-rate fields at various spatial and temporal scales. The posterior is the distribution of functions that interpolate the given GNSS data, which we then differentiate using a radial basis function, finite difference scheme to determine the strain-rates. We apply PyGeoNS to Pacific Northwest, Southern California and South Island, New Zealand. Transient strain-rates in the Pacific Northwest image the transient variation of surface strain-rates during slow slip events. Estimated strain-rates across Southern California and South Island include both transient and secular deformation and in California account for the creeping section of the San Andreas fault. The strain-rates resolve both secular strain-accumulation and postseismic deformation, specifically focusing on the strain-accumulation along the San Andreas fault in California and the Marlborough fault system in New Zealand, along with the postseismic deformation following the 2010 El Mayor-Cucapah and the 2019 Ridgecrest earthquakes in California and the 2010 Darfield and 2016 Kaikoura earthquakes in New Zealand.

Presenting Author: Eric A. Hetland

Authors