89-7 Fault Dynamics Understanding through Continuous GNSS and High-Resolution Interferometric Synthetic Aperture Radar Data Fusion

Session: Advancing Earthquake Geology and Surficial Deformation from Geologic Provinces to Political Entities through Multidisciplinary High-Resolution Data

Presenting Author:

Authors:

Abstract:

In the absence of earthquakes, motion along faults is accommodated by continuous or episodic creep. This slow movement causes off-fault elastic deformation as the creeping section pulls away from the locked section. One observable result is increasing surface deformation as a function of distance from the fault. We present surface deformation observations around the Rock Valley Fault Zone— a left lateral strike slip regime in the Nevada National Security Site in southern Nevada— from two highly complementary modalities: continuous GNSS and high-resolution synthetic aperture radar interferometry (InSAR). Specifically, this work aims to better understand fault creep and resulting surface deformation along the Rock Valley Fault Zone—lateral strike slip regime-- in the Nevada National Security Site. This work is part of the Rock Valley Direct Comparison experiment, which compares earthquake and explosion seismic wave propagation through geologic structures.

GNSS yields daily measurements from discrete, but sparse, locations across a large regional scale that are very sensitive to lateral motion. Geodetic stations were installed along a transect oriented perpendicular to the trend of the fault zone to capture deformation occurring at distances out from the zone. InSAR, on the other hand, provides spatially continuous, high resolution digital elevation models that are sensitive to lateral and vertical surface changes. SAR imaging was constrained to Rock Valley to capture near-fault surface changes. InSAR requires careful acquisition and co-registration of two SAR images. The displacement vectors computed as part of the co-registration process, to map one image to the other, can be analyzed for lateral motion throughout the scene; these vectors are at a fraction of the image resolution, affording continuous displacement data that can be integrated with geodetic velocity and strain data. Completing InSAR processing aids in detecting vertical displacements, as well.

Preliminary observations indicate some degree of left-lateral motion across the fault, consistent with recent tectonic activity, with SAR displacement vectors providing finer details across the valley. Although very little motion has occurred since the start of data acquisition, we are already able to demonstrate the utility and sensitivity of this data integration approach.

SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-7790

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