Research Expedition Collects Cores, Geophysical Data from Cascadia Subduction Zone
To better understand the geophysical characteristics and seismic history of the Cascadia Subduction Zone, USGS researchers conduct fieldwork at sea to collect evidence of turbidity currents from underwater landslides likely caused by earthquake shaking.
Crews aboard the research vessel operate 24 hours a day, working 12-hour shifts. Researchers conduct sonar surveys to visualize the contours of the seafloor with sound. These data make it possible to locate underwater landslides, image layered sediments characteristic of turbidity current deposits, and identify faults beneath the seafloor.
Researchers can then better target where to collect sediment cores, which are analyzed back on shore, by being are split, photographed, scanned, and described in a lab. Samples are also collected for radiometric dating to reveal details about when the earthquakes and landslides occurred. Additionally, cores collected on either side of a fault can help determine how recently or by how much the fault has moved.
Subduction zones are the source of some of the largest earthquakes in recorded history. Understanding how these tectonic margins behave—where, how often, and how much they move—is critical to assessing the potential hazards they pose to communities and infrastructure.
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Societal Issue: Uncertainty related to rupture extent, slip distribution, and recurrence of past subduction megathrust earthquakes in the Pacific Northwest (northern CA, OR, WA, and southern BC) leads to ambiguity in earthquake and tsunami hazard assessments and hinders our ability to prepare for future events.ByNatural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, 3-D CT Core Imaging Laboratory, Core Preparation and Analysis Laboratory and Sample Repositories, Multi-Sensor Core Logger Laboratory, Deep Sea Exploration, Mapping and Characterization, Subduction Zone ScienceEXPRESS: Expanding Pacific Research and Exploration of Submerged Systems
EXPRESS is a multi-year, multi-institution cooperative research campaign in deep sea areas of California, Oregon, and Washington, including the continental shelf and slope. EXPRESS data and information are intended to guide wise use of living marine resources and habitats, inform ocean energy and mineral resource decisions, and improve offshore hazard assessments.ByCoastal and Marine Hazards and Resources Program, Pacific Coastal and Marine Science Center, 3-D CT Core Imaging Laboratory, Core Preparation and Analysis Laboratory and Sample Repositories, Multi-Sensor Core Logger Laboratory, Organic Geochemistry Laboratory, Deep Sea Exploration, Mapping and Characterization - News
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