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A Compound Faulting Model for the 1975 Kalapana, Hawaii, Earthquake, Landslide, and Tsunami

Supporting Files


Details

  • Journal Title:
    Journal of Geophysical Research: Solid Earth
  • Personal Author:
  • NOAA Program & Office:
    NWS (National Weather Service)
  • Description:
    The Kalapana, Hawaii, MW 7.7 earthquake on November 29, 1975 generated a local tsunami with at least 14.3 m runup on the southeast shore of Hawaii Island adjacent to Kilauea Volcano. This was the largest locally generated tsunami since the great 1868 Ka'u earthquake located along-shore to the southwest. Well-recorded tide gauge and runup observations provide a key benchmark for studies of statewide tsunami hazards from actively deforming southeast Hawaii Island. However, the source process of the earthquake remains controversial, with coastal landsliding and/or offshore normal or thrust faulting mechanisms having been proposed to reconcile features of seismic, geodetic, and tsunami observations. We utilize these diverse observations for the 1975 Kalapana earthquake to deduce a compound faulting model that accounts for the overall tsunamigenesis, involving both landslide block faulting along the shore and slip on the island basal décollement. Thrust slip of 4.5–8.0 m on the offshore décollement produces moderate near-field runup but controls the far-field tsunami. The slip distribution implies that residual strain energy was available for the May 4, 2018 MW 7.2 thrust earthquake during the Kilauea-East Rift Zone eruption. Local faulting below land contributes to geodetic and seismic observations, but is non-tsunamigenic and not considered. Slip of 4–10 m on landslide-like faults, which extend from the Hilina Fault Zone scarp to offshore shallowly dipping faults reaching near the seafloor, triples the near-field tsunami runup. This compound model clarifies the roles of the faulting components in assessing tsunami hazards for the Hawaiian Islands.
  • Keywords:
  • Source:
    Journal of Geophysical Research: Solid Earth, 126(11)
  • DOI:
  • ISSN:
    2169-9313 ; 2169-9356
  • Format:
    PDF
  • Publisher:
    American Geophysical Union (AGU)
  • Document Type:
    Journal Article
  • Funding:
    Grant no. NA19NWS4670012
  • Place as Subject:
    Hawaii
  • Rights Information:
    Other
  • Compliance:
    CHORUS
  • Main Document Checksum:
    urn:sha256:f793be9560d6aa1fdac7898d0fd9500e20773c35545a69d18ee166a9e6f7a8bd
  • Download URL:
  • File Type:
    Filetype[PDF - 6.81 MB ]

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