2019 Geophysical surveys and sediment coring in southern Cascadia (northern California)

Science Center Objects

Objectives: The sediment sampling and geophysical surveys were designed to address questions regarding tectonic activity and sediment dispersal patterns across the margin. Survey tracks and sampling sites were targeted to investigate the Eel River forearc basin sedimentation history and the sources and pathways of sediment gravity flows, both of which provide context for interpreting the deep-sea turbidite record. In addition, these data will provide key information for understanding the earthquake history of active structures in southern Cascadia.

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.

2019 USGS regional geophysical surveys of northern and central Cascadia (offshore Washington and Oregon)

Participants

USGS Scientists: Jenna Hill (PI), Janet Watt, Danny Brothers, Nora Nieminski, Gerry Hatcher, Brandon Nasr, Pete Del Ferro, Jenny and UCSC Student: Travis Alonghi (Photo 7)

Partners

Bureau of Ocean and Energy Management (BOEM)

Platform Used

M/V Bold Horizon

Data Collected

Jumbo piston/gravity sediment cores (Photos 1-5), Sparker multi-channel seismic (MCS), Chirp sub-bottom profiler (Photo 6)

Highlights

  • >2,100 km of Chirp sub-bottom and sparker multi-channel seismic data collected
  • ~40 sediment cores (3-7 m in length) recovered

 

A man and woman work on a steel core on the deck of a ship.

Photo 1: USGS scientists Pete Dal Ferro and Jenny McKee securing a recently collected jumbo piston core (JPC) on the back deck of M/V Bold Horizon for preliminary core processing. Credit: Jenna Hill, USGS

A smiling woman holds onto a sediment core.

Photo 2: USGS Mendenhall postdoc,Nora Nieminski showing some love for a trigger core recovered from the Cascadia subduction zone. Credit: Jenna Hill, USGS

 

A smiling woman holds a spring-loaded instrument against a sediment core.

Photo 3: USGS scientist Janet Watt making a shear vane measurement on a gravity core to understand how the seafloor responds to earthquake shaking. Credit: Jenna Hill, USGS

People work on the deck of a ship securing a long coring device.

Photo 4: USGS scientists Nora Nieminski, Jenna Hill, and Brandon Nasr working to cap and secure a trigger core on deck. Trigger cores can provide important information about seafloor sediments just below the seafloor.

Four people stand around a coring device on the deck of a ship.

Photo 5: USGS scientists Brandon Nasr, Jenna Hill, Nora Nieminski, and Jenny McKee removing a sediment-filled core liner from the jumbo piston core barrel with the picturesque northern California coastline in the background. Credit: Janet Watt, USGS

Two men on the deck of a ship stand near a sonar device readying it for deployment.

Photo 6: UCSC student Travis Alonghi and USGS scientist Danny Brothers deploying the Chirp sub-bottom profiler at sunset from M/V Bold Horizon. Credit: Janet Watt, USGS 

A group of people stand, smiling for the camera, on the deck of a ship at sea with the Golden Gate Bridge in the background

Photo 7: USGS scientists on the back deck of the M/V Bold Horizon in San Francisco Bay: (back row: left to right) Brandon Nasr, Danny Brothers, Travis Alonghi [UCSC Student], Gerry Hatcher, Jenna Hill, Pete Dal Ferro; (front row: left to right) USGS scientists Janet Watt, Nora Nieminski, and Jenny McKee. Credit: Nora Nieminski, USGS