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Jason Padgett

I'm a coastal field geologist and it is my goal to help improve understanding of megathrust earthquakes and coastal hazards. I analyze geologic evidence of past earthquakes, tsunamis, storm surge, and coastal landscape evolution. My research interests revolve around relative sea-level changes over varying timescales from minutes to millennia.

Core Lab and Sample Repositories

Two women work in a laboratory with a sediment core on a table.

Core lab and cold sample storage

Core Lab

Multi-Sensor Core Logger Lab

A woman wearing a lab coat and rubber gloves stands in a lab near an apparatus with a long track that holds a sediment core.

Multi-sensor core logger (MSCL)

MSCL Lab

3-D CT Core Imaging Lab

Computerized tomography image of a coral core section next to its corresponding plot of annual density values.

Rotating x-ray computed tomography (RXCT)

RXCT Lab

My field-based interdisciplinary research bridges the gap between short-term instrumental records and long-term geologic reconstructions of coastal landscape evolution. To extend seismic and coastal hazard records over centennial and millennial timescales, I employ a combination of paleoseismology, micropaleontology, stratigraphy, geomorphology, geospatial analysis, geophysical modeling, and sea-level research techniques. Inferences of coseismic land-level change, tsunami, and storm surge inundation heights are supported through sedimentological, geochemical, and microfossil (e.g., foraminifera) laboratory analyses. I specialize in foraminifera analysis, which is particularly valuable to reconstruct past relative sea-level elevations and identifying anomalous sand beds deposited by storms and tsunamis. I construct numerical age models to develop robust chronologies based on radiocarbon, 137Cs, heavy metal concentrations, and optically stimulated luminescence (OSL) dating techniques. Much of my research is based along the Cascadia coastal margin, e.g., northern Humboldt Bay and Washington; however, I am also a part of active research projects in Rhode Island and Alaska.

At Pacific Coastal Marine Science Center, I manage the core labs and I’m the curator of the core repository. In the core labs, we conduct sediment core analysis, which could involve RXCT density imagery, MSCL analysis, core splitting, and subsampling. At the core repository, we maintain a vast of collection of >17,000 sediment cores which have been collected over the past ~50 years from all over the world.

Professional Experience

  • 2021: Lecturer and Research Associate, Department of Geology, Humboldt State University

  • 2021: Lecturer, Department of Geosciences, University of Rhode Island

  • 2019-2020: Postdoctoral Research Associate, Department of Geography, Durham University

     

Education and Certifications

  • 2019: Ph.D. Biological and Environmental Sciences, Geosciences, University of Rhode Island

  • 2013: M.S. Environmental Systems Geology, Humboldt State University

  • 2010: B.S. Oceanography & Geology minor, Humboldt State University

Science and Products

Reproducibility and variability of earthquake subsidence estimates from saltmarshes of a Cascadia estuary

We examine fossil foraminiferal assemblages from 20 sediment cores to assess sudden relative sea-level (RSL) changes across three mud-over-peat contacts at three salt marshes in northern Humboldt Bay, California (~44.8°N, -124.2°W). We use a validated foraminiferal-based Bayesian transfer function to evaluate the variability of subsidence stratigraphy at a range of 30-6000 m across an estuary. We
Authors
Jason Scott Padgett, Simon E. Engelhart, Harvey M. Kelsey, Robert C. Witter, Niamh Cahill
By
Ecosystems Mission Area, Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Alaska Science Center, Pacific Coastal and Marine Science Center

A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis

A new history of great earthquakes (and their tsunamis) for the central and southern Cascadia subduction zone shows more frequent (17 in the past 6700 yr) megathrust ruptures than previous coastal chronologies. The history is based on along-strike correlations of Bayesian age models derived from evaluation of 554 radiocarbon ages that date earthquake evidence at 14 coastal sites. We reconstruct a
Authors
Alan Nelson, Christopher Duross, Robert C. Witter, Harvey M. Kelsey, Simon E. Engelhart, Shannon A. Mahan, Harrison J. Gray, Andrea D. Hawkes, Benjamin P. Horton, Jason S. Padgett
By
Natural Hazards Mission Area, Geologic Hazards Science Center, Pacific Coastal and Marine Science Center

Non-USGS Publications**

Padgett, J.S., Engelhart, S.E., Kelsey, H.M., Witter, R.C., Cahill, N. and Hemphill-Haley, E., 2021. Timing and amount of southern Cascadia earthquake subsidence over the past 1700 years at northern Humboldt Bay, California, USA. Bulletin, 133(9-10), pp.2137-2156.
Hong, I., Horton, B.P., Hawkes, A.D., O'Donnell III, R.J., Padgett, J.S., Dura, T. and Engelhart, S.E., 2021. Diatoms of the intertidal environments of Willapa Bay, Washington, USA as a sea-level indicator. Marine Micropaleontology, 167, p.102033.
Padgett, J.S., Kelsey, H.M. and Lamphear, D., 2019. Upper-plate deformation of Late Pleistocene marine terraces in the Trinidad, California, coastal area, southern Cascadia subduction zone. Geosphere, 15(4), pp.1323-1341.
Padgett, J.S., Engelhart, S.E., Hoffmann, G., Rosentau, A. and Yu, F., 2018. Sea-level change from minutes to millennia: first meeting of IGCP Project 639 in Oman. Episodes., 41(2), pp.115-118.

**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

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Science and Products

  • Publications

    Reproducibility and variability of earthquake subsidence estimates from saltmarshes of a Cascadia estuary

    We examine fossil foraminiferal assemblages from 20 sediment cores to assess sudden relative sea-level (RSL) changes across three mud-over-peat contacts at three salt marshes in northern Humboldt Bay, California (~44.8°N, -124.2°W). We use a validated foraminiferal-based Bayesian transfer function to evaluate the variability of subsidence stratigraphy at a range of 30-6000 m across an estuary. We
    Authors
    Jason Scott Padgett, Simon E. Engelhart, Harvey M. Kelsey, Robert C. Witter, Niamh Cahill
    By
    Ecosystems Mission Area, Natural Hazards Mission Area, Coastal and Marine Hazards and Resources Program, Alaska Science Center, Pacific Coastal and Marine Science Center

    A maximum rupture model for the central and southern Cascadia subduction zone—reassessing ages for coastal evidence of megathrust earthquakes and tsunamis

    A new history of great earthquakes (and their tsunamis) for the central and southern Cascadia subduction zone shows more frequent (17 in the past 6700 yr) megathrust ruptures than previous coastal chronologies. The history is based on along-strike correlations of Bayesian age models derived from evaluation of 554 radiocarbon ages that date earthquake evidence at 14 coastal sites. We reconstruct a
    Authors
    Alan Nelson, Christopher Duross, Robert C. Witter, Harvey M. Kelsey, Simon E. Engelhart, Shannon A. Mahan, Harrison J. Gray, Andrea D. Hawkes, Benjamin P. Horton, Jason S. Padgett
    By
    Natural Hazards Mission Area, Geologic Hazards Science Center, Pacific Coastal and Marine Science Center

    Non-USGS Publications**

    Padgett, J.S., Engelhart, S.E., Kelsey, H.M., Witter, R.C., Cahill, N. and Hemphill-Haley, E., 2021. Timing and amount of southern Cascadia earthquake subsidence over the past 1700 years at northern Humboldt Bay, California, USA. Bulletin, 133(9-10), pp.2137-2156.
    Hong, I., Horton, B.P., Hawkes, A.D., O'Donnell III, R.J., Padgett, J.S., Dura, T. and Engelhart, S.E., 2021. Diatoms of the intertidal environments of Willapa Bay, Washington, USA as a sea-level indicator. Marine Micropaleontology, 167, p.102033.
    Padgett, J.S., Kelsey, H.M. and Lamphear, D., 2019. Upper-plate deformation of Late Pleistocene marine terraces in the Trinidad, California, coastal area, southern Cascadia subduction zone. Geosphere, 15(4), pp.1323-1341.
    Padgett, J.S., Engelhart, S.E., Hoffmann, G., Rosentau, A. and Yu, F., 2018. Sea-level change from minutes to millennia: first meeting of IGCP Project 639 in Oman. Episodes., 41(2), pp.115-118.

    **Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.

  • Multimedia
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