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Puget Slides Project

Updated: Dec 30, 2021


Tying deep-seated landslides to base level, earthquakes, and a changing climate in the Pacific Northwest




Funding Source: US National Science Foundation

Collaborators: Adam Booth (lead PI) and Abigail Underwood (graduate student) - Portland State University, Erin Wirth, Ian Stone, alex grant, Sean LaHusen - USGS, Joe Wartman - UW

GeoScape Team Members: Alison Duvall (co-PI), Erich Herzig (graduate student)


Understanding controls on past landsliding in the Puget Sound and surrounding region will provide valuable insight into predicting future landslide occurrence under chaning climatic, seismic, and land-use conditions.

Overview


The goal of this project is to quantify the response of prehistoric, deep-seated landslides to changing base level, seismicity, and climate over the Holocene in the Puget Sound Lowlands, Washington, United States. This will allow us to answer the fundamental science questions of how the geomorphic record reflects changes in the drivers of landscape evolution, including extreme events, and how Earth’s surface is likely to respond to future forcings.


To answer these questions we first combine novel analyses of airborne lidar data with an extensive traditional radiocarbon dating campaign to define an “age-roughness” model [LaHusen et al., 2016; Booth et al., 2017], allowing us to approximately date thousands of landslides throughout the Puget Lowlands. We then analyze the inferred spatial and temporal patterns of landsliding against detailed independent records of climate change, base level change, and seismic shaking over the Holocene.


Broadly, this will allow us to determine if the location and timing of deep-seated landslides is consistent or inconsistent with known spatio-temporal patterns of fundamental triggers and to establish the relative importance of those triggers in creating the geomorphic record of deep-seated landslides.


As a specific application with important hazard implications, we will simulate dozens of hypothetical Seattle Fault earthquakes by generating high spatial resolution synthetic broadband seismograms, including the effects of 3D basin amplification, rupture directivity, and near-surface site response, to test predictions of where landslides may have occurred in response to the ~1,100 ybp Seattle Fault earthquake.


Related Publications:


LaHusen, S.R., Duvall, A.R., Booth, A.M., Struble, W., Grant, A., Wartman, J., Roering,

J., and Montgomery, D.R., 2020, Storms trigger more deep-seated landslides than

Cascadia earthquakes in the Oregon Coast Range, USA. Science Advances, 6(38), DOI:10.1126/sciadv.aba6790


Booth, A.M., LaHusen, S.R., Duvall, A.R., and Montgomery, D.R., 2017, Holocene

history of deep-seated landsliding in the North Fork Stillaguamish River valley from

surface roughness analysis, radiocarbon dating, and numerical landscape evolution

modeling: Journal of Geophysical Research, Earth Surface, v. 122, 17 pp.

doi:10.1002/2016JF003934.


LaHusen, S.R., Duvall, A.R., Booth, A.M., and Montgomery, D.R., 2016, Surface

roughness dating of long-runout landslides near Oso, Washington (USA), reveals

persistent postglacial hillslope instability: Geology, v.44(2), 4 pp.

doi:10.1130/G37267.1.

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