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Revisiting the 1959 Hebgen Lake earthquake using optical image correlation; new constraints on near-field 3D ground displacement
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  • Lucia Andreuttiova,
  • James Hollingsworth,
  • Pieter Vermeesch,
  • Thomas Matthew Mitchell,
  • Eric A Bergman
Lucia Andreuttiova
University College London

Corresponding Author:[email protected]

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James Hollingsworth
Université Grenoble Alpes
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Pieter Vermeesch
University College London
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Thomas Matthew Mitchell
University College London
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Eric A Bergman
Global Seismological Services
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Abstract

Surface displacement data from earthquakes are essential for characterizing the fault slip distribution with depth. The Hebgen Lake earthquake was a large normal event with a geometrically complex surface rupture, which broke across mountainous terrain. This study takes advantage of high-resolution historical stereo-imagery to measure the vertical and horizontal displacement from correlation of the orthorectified pre- and post-earthquake image mosaics. The results reveal new strike-slip surface ruptures which are possibly associated with the aftershocks from 18\textsuperscript{th} August 1959. The kinematic role of these structures is likely related to the accommodation of internal deformation induced by the mainshock strain field. Additionally, the comparison of our results with the existing displacement data shows that the OIC-derived offsets often exceed the field measurements by $>$50\%. We attribute this difference to the inelastic damage accommodated off the main rupture.