Geophysical Validation of Tidally Calibrated Strains From the Novel Alto Tiberina Near Fault Observatory Strainmeter Array (TABOO-NFO-STAR)
Six borehole tensor strainmeters, installed between Fall 2021 to Spring 2022, comprise a strainmeter array along the Alto Tiberina fault system (STAR), Italy. The array provides an opportunity to investigate deformation from seismic and aseismic slip on hazardous high- and low-angle normal faults. Prior to use in tectonic applications, the strainmeters require in-situ calibration and correction for non-tectonic signals. We tidally calibrate the instruments and test the results against environmental signals and signals from coseismic deformation associated with polarized compressional body waves and static offsets originating from local to teleseismic distances. Calibrated analyses demonstrate that the STAR sites deviate from typical assumptions of isotropic, homogeneous conditions, with four of the six strainmeters (TSM3-6) exhibiting negative areal coupling that complicates analysis of surface loads. For coseismic deformation, the results show interstation precision and accuracy to nanostrain levels. Potential complications for interpreting deformation at TSM3 may arise from dynamically triggered near-borehole fracture slip and fluid flow, but apparently only in response to high strain rates, while low strain rates remain consistent with our expectations. Although use of the tidal calibrations seems valid for TSM1, 2, 3, 5, and 6, future improvement may be possible as longer, stable timeseries become available, with particular attention to TSM4. Overall, the present analyses demonstrate expanded geodetic capability for detecting nanostrain deformation in the Alto Tiberina Near Fault Observatory, which other observatories have shown would be needed to detect slow, transient slip, and both coseismic and dynamic strain from local to teleseismic earthquakes.
Session: Cryptic Faults: Advances in Characterizing Low Strain Rate and Environmentally Obscured Faults - II
Type: Oral
Room: Tubughnenq’ 3
Date: 5/1/2024
Presentation Time: 11:15 AM (local time)
Presenting Author: Catherine Hanagan
Student Presenter: No
Additional Authors
Catherine Hanagan Presenting Author Corresponding Author chanagan@usgs.gov U.S. Geological Survey |
Eugenio Mandler eugenio.mandler@ingv.it Istituto Nazionale di Geofisica e Vulcanologia |
Richard Bennett rb0@arizona.edu University of Arizona |
Lauro Chiaraluce lauro.chiaraluce@ingv.it Istituto Nazionale di Geofisica e Vulcanologia |
Mike Gottlieb mike.gottlieb@earthscope.org EarthScope Consortium |
Adriano Gualandi adriano.gualandi@ingv.it Istituto Nazionale di Geofisica e Vulcanologia |
Amanda Hughes anhughes@arizona.edu University of Arizona |
Johnson Wade wade.johnson@earthscope.org EarthScope Consortium |
David Mencin david.mencin@earthscope.org EarthScope Consortium |
Simona Pierdominici simona.pierdominici@gfz-potsdam.de GFZ Potsdam, Potsdam, , Germany |
Geophysical Validation of Tidally Calibrated Strains From the Novel Alto Tiberina Near Fault Observatory Strainmeter Array (TABOO-NFO-STAR)
Category
Cryptic Faults: Advances in Characterizing Low Strain Rate and Environmentally Obscured Faults
Description