Ridgecrest Deformation as Probe of Advanced Geodetic Techniques

We examine the geodetic deformation patterns as determined in GNSS, radar, and optical observations from processed signals at JPL and other analysis centers. GNSS network processing is well established, so the Ridgecrest earthquakes including the M7.1 event of July 5, 2019 offer a demonstration of the extent of the coherent pattern under modern data collection and processing conditions, and shows standard limitations such as common mode error and unstructured noise. However, a purely GNSS-geodetic inversion for a nine-parameter fault slip model (using the downhill simplex method, with Okada uniform dislocation) accounts for 93% of the variance for the breaks at 431 regional stations, with reasonable matches for magnitude (7.04 vs 7.1 Mw reported) rake ( -177 vs seismic -173), and strike (320 vs. seismic 322). This degree of match to such a simple optimized model suggests the Ridgecrest event is fundamentally simple, despite apparent superficial complications. A contrasting geodetic method uses satellite repeat-pass interferograms. This variety of data have far higher spatial resolution, but lower temporal resolution and other limitations. These are currently supplied from non-US agencies including JAXA, illustrating the capabilities we can expect from the awaited NISAR mission in event of earthquakes on land. The Ridgecrest region has not had a history of UAVSAR observations, so we do not have coseismic repeat-pass interferograms, but we look for interesting effects of the earthquake in radar reflectivity and polarimetry images and with fresh visits create the basis for postseismic deformation images. In addition an airborne optical array is in progress, designed for structure from motion reconstruction of the surface shape, and how the designed sensitivity and resolution features reveal earthquake-generated features such as scarps. Generally each observation type provides characteristic spatial and temporal resolution, with unavoidable but small distortions and noise, which maps to particular earthquake science features.