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2018 Regional geophysical surveys of southern Cascadia (offshore northern California and southern Oregon) Completed

By Pacific Coastal and Marine Science Center August 18, 2020

Regional geophysical surveys conducted offshore of northern California and southern Oregon in 2018, a USGS-Humboldt State University partnership

These surveys are part of the USGS project, “Cascadia Subduction Zone Marine Geohazards.”

Illustration of the seafloor off the coast with areas highlighted to show detail.
Sources/Usage: Public Domain. View Media Details
2018 USGS regional geophysical surveys of southern Cascadia (offshore northern California and southern Oregon)

Objectives

Characterize offshore geohazards and source-to-sink sedimentary dynamics offshore southern Cascadia.

Participants

USGS Scientists Janet Watt and Jenna Hill (PIs), Daniel Brothers, Jared Kluesner, Rachel Marcuson, Chuck Worley (Photo 3)

Partner

Humboldt State University (Photo 1)

Platform Used

Humboldt State University’s R/V Coral Sea (Photo 5)

Data Collected

Sparker multi-channel seismic (MCS), Chirp sub-bottom, magnetometer (Photos 2 and 4)

Highlights

  • Active faulting and folding along numerous cross-shore structures on the shelf; including the Table Bluff anticline, Little Salmon, Mad River, and Bald Mountain-Big Lagoon faults
  • First high-resolution sparker imagery of faulting at the deformation front (~3,500 m water depth)

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 

A small group gathers around a woman who's extracting a sediment core from a marshy area while a man talks.
Sources/Usage: Public Domain. View Media Details
Photo 1: Humboldt State University Assistant Professor Melanie Michalak (kneeling) and California State Geological Survey scientist Jay Patton (standing, center) explaining core stratigraphy within Humboldt slough and evidence for past tsunami inundation. Integrating evidence of past earthquakes and tsunamis from offshore and onshore geologic evidence is key to understanding the hazards posed by the Cascadia subduction zone.
Geophysical equipment sits on the deck of a boat.
Sources/Usage: Public Domain. View Media Details
Photo 2: Marine magnetometer (in storage box on left) and chirp sub-bottom profiler on the back deck of R/V Coral Sea.

~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 

A group of 6 people wearing lifejackets stand on a ship smiling up at the camera person.
Sources/Usage: Public Domain. View Media Details
Photo 3: USGS scientists (left to right) Jenna Hill, Chuck Worley, Rachel Marcuson, Janet Watt, Danny Brothers, and Jared Kluesner on the back deck of Humboldt State University’s R/V Coral Sea.
Four people on the stern of a boat wear life jackets and prepare a long cable.
Sources/Usage: Public Domain. View Media Details
Photo 4: USGS science crew prepare to pull in the multi-channel streamer to troubleshoot the system.
Photo of a research boat anchored on the water.
Sources/Usage: Public Domain. View Media Details
Photo 5: Humboldt State University’s research vessel R/V Coral Sea.
  • Overview

    Regional geophysical surveys conducted offshore of northern California and southern Oregon in 2018, a USGS-Humboldt State University partnership

    These surveys are part of the USGS project, “Cascadia Subduction Zone Marine Geohazards.”

    Illustration of the seafloor off the coast with areas highlighted to show detail.
    Sources/Usage: Public Domain. View Media Details
    2018 USGS regional geophysical surveys of southern Cascadia (offshore northern California and southern Oregon)

    Objectives

    Characterize offshore geohazards and source-to-sink sedimentary dynamics offshore southern Cascadia.

    Participants

    USGS Scientists Janet Watt and Jenna Hill (PIs), Daniel Brothers, Jared Kluesner, Rachel Marcuson, Chuck Worley (Photo 3)

    Partner

    Humboldt State University (Photo 1)

    Platform Used

    Humboldt State University’s R/V Coral Sea (Photo 5)

    Data Collected

    Sparker multi-channel seismic (MCS), Chirp sub-bottom, magnetometer (Photos 2 and 4)

    Highlights

    • Active faulting and folding along numerous cross-shore structures on the shelf; including the Table Bluff anticline, Little Salmon, Mad River, and Bald Mountain-Big Lagoon faults
    • First high-resolution sparker imagery of faulting at the deformation front (~3,500 m water depth)

    ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 

    A small group gathers around a woman who's extracting a sediment core from a marshy area while a man talks.
    Sources/Usage: Public Domain. View Media Details
    Photo 1: Humboldt State University Assistant Professor Melanie Michalak (kneeling) and California State Geological Survey scientist Jay Patton (standing, center) explaining core stratigraphy within Humboldt slough and evidence for past tsunami inundation. Integrating evidence of past earthquakes and tsunamis from offshore and onshore geologic evidence is key to understanding the hazards posed by the Cascadia subduction zone.
    Geophysical equipment sits on the deck of a boat.
    Sources/Usage: Public Domain. View Media Details
    Photo 2: Marine magnetometer (in storage box on left) and chirp sub-bottom profiler on the back deck of R/V Coral Sea.

    ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 

    A group of 6 people wearing lifejackets stand on a ship smiling up at the camera person.
    Sources/Usage: Public Domain. View Media Details
    Photo 3: USGS scientists (left to right) Jenna Hill, Chuck Worley, Rachel Marcuson, Janet Watt, Danny Brothers, and Jared Kluesner on the back deck of Humboldt State University’s R/V Coral Sea.
    Four people on the stern of a boat wear life jackets and prepare a long cable.
    Sources/Usage: Public Domain. View Media Details
    Photo 4: USGS science crew prepare to pull in the multi-channel streamer to troubleshoot the system.
    Photo of a research boat anchored on the water.
    Sources/Usage: Public Domain. View Media Details
    Photo 5: Humboldt State University’s research vessel R/V Coral Sea.