Department of Earth and Space Sciences Faculty Research

Permanent URI for this collectionhttps://digital.lib.washington.edu/handle/1773/22701

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Earthquake and Tsunami Early Warning on the Cascadia Subduction Zone: A Feasibility Study for an Offshore Geophysical Monitoring Network
(2023-10-19) Schmidt, David; Wilcock, William; LeVeque, Randall; Gonzalez, Frank; Cram, Geoffrey; Manalang, Dana; Harrington, Mike; Roland, Emily; Bodin, Paul
This study advances efforts to implement earthquake early warning along the U.S. West Coast. An optimized detection and warning system must be adapted to the local geology and particular earthquake risks for a region. Compared to other plate boundaries, residents of subduction zone environments likely benefit the greatest from earthquake early warning because the population is likely to receive the longest warning times. This is because the major inland populations are far from the earthquake source, which lies almost entirely offshore. But subduction zones present a challenge: the geophysical network that detects the earthquake is limited to the land, rather than surrounding the earthquake source region offshore. Subduction zones also pose a second major hazard in the form of a tsunami that is frequently triggered by the offshore earthquake. Therefore, the timeliness, accuracy, and reliability of earthquake and tsunami early warning in subduction zones, such as found in the Pacific Northwest, would be enhanced by offshore geophysical instrumentation. However, offshore instrument networks are technically challenging to design, install, and maintain. The feasibility and design of an offshore geophysical network for earthquake and tsunami early warning in the Pacific Northwest was evaluated by a team of scientists and engineers at the University of Washington with support from the Gordon and Betty Moore Foundation. The team’s goals were to (1) consider the justification for such a system, (2) identify the high-level system specifications, (3) evaluate current and emerging technologies, (4) determine the feasibility and approximate costs of illustrative designs, and (5) make recommendations about the path forward. To inform the study, a workshop of over 100 participants was organized after some preparatory work (Wilcock et al., 2016). Attendees were drawn primarily from academia, but representatives from federal agencies, industry, the emergency management community, and the media were also present (Schmidt et al.,2018). The deliberations and recommendations of the workshop were important in guiding the completion of the study. This report and its supporting documents present the study’s results. The instrument network designs presented here are neither final nor optimized, but rather are illustrative of options that utilize established and emergent approaches. While the report notes the necessity of incorporating an offshore geophysical network into a comprehensive strategy for preparedness, education, warning, and response, it does not present a holistic mitigation plan, nor does it explore in any detail how offshore data would be integrated with existing warning systems that are operated by the United States Geological Survey (USGS) and the National Oceanic and Atmospheric Administration (NOAA). This report is best viewed as a resource on the scientific and technical considerations, as well as the societal benefit, for earthquake and tsunami detection in subduction zones, such as in Cascadia and similar locations across the planet with populations at risk.
Datasets used to condition inversions of shear stress at the ice-bed interface on Thwaites Glacier
(2022-06) Hoffman, Andrew; Christianson, Knut
Included in this handle are input data used in the inversions described in the paper "The impact of basal roughness on Thwaites Glacier sliding." These include surface elevation, and basal topographies used to construct the meshes that define the computational domain as well as the surface velocities that were used to condition the inverse problem. Swath radar technology enables three-dimensional mapping of modern glacier beds over large areas at resolutions that are higher than those typically used in ice-flow models. These data and may enable new understanding of processes at the ice-bed interface. Here, we use two densely-surveyed swath-mapped topographies (50 m^2 resolution) of Thwaites Glacier to investigate the sensitivity of inferred basal friction proxies to bed roughness magnitude and orientation. Included in this archive are the bed topographies, surface topographies and surface velocities used to infer the basal resistance of two interior regions of Thwaites Glacier.
gnss-ir derived accumulation history at the GNSS sites LTHW, UTHW, and KHLR maintained by unavco and the polenet team.
(2022-05-17) Hoffman, Andrew; Christianson, Knut
Accumulation time series were determined using GNSS interferometric reflectometry and MCMC inverse methods. Sites include KHLR, LTHW, and UTHW long-term GNSS stations on the Thwaites and Kohler glaciers. Included are the daily reflector heights of the phase center of the GNSS reciever antenna derived from median filtering daily reflections from satellite azimuths below 7 degrees. Also included are the daily accumulation time series determined from reflector height change at the site of each receiver.
Long Beach Berm Modeling Study
(2018-03-28) Gonzalez, Frank I.; LeVeque, Randall J.
A berm design was developed for compatibility with guidelines published by the Federal Emergency Management Agency (FEMA) for vertical evacuation structures; the design utilized the maximum flooding depth results of a previous modeling assessment of the Long Beach berm site (FEMA, 2012; González, et al., 2013). Recently, the American Society of Civil Engineers (ASCE) published new ASCE 7-16 guidelines that are expected to be adopted in the near future for tsunami vertical evacuation structures (ASCE, 2017). One major difference between the FEMA and ASCE guidance is that ASCE 7-16 imposes exceedance criteria on the maximum wave height values offshore at the 100 m isobath (the “eta100 criteria,” see Appendix A). Tests of the berm design for both FEMA and ASCE minimum height criteria were conducted with the GeoClaw model (Berger, et al., 2010; LeVeque, et al., 2011; Gonzalez, et al., 2011; NOAA, 2011). Several issues arose in the interpretation and application of ASCE 7-16 in the context of hydrodynamic models that provide twodimensional solutions of tsunami flow depth and other parameters. Nonetheless, we conclude that the new berm design is not compliant with ASCE 7-16 minimum berm height criteria, and is marginally compliant with the FEMA (2012) criteria that guided the berm design.
Ice-sheet height and thickness changes from ICESat to ICESat-2.
(2020) Smith, Ben; Fricker, Helen; Gardner, Alex; Medley, Brooke; Nilsson, Johan; Paolo, Fernando; Holschuh, Nicholas; Adusumilli, Susheel; Brunt, Kelly; Csatho, Bea; Harbeck, Kaitlin; Markus, Thorsten; Neumann, Thomas; Siegfried, Matthew; Zwally, H. Jay
These data represent ice-column thickness-change-rate estimates based on data from NASA's ICESat and ICESat-2 satellites. These data aided the first estimates of ice-sheet mass change from these two missions, spanning the 16 years from 2003 to 2019, taking advantage of the high vertical and horizontal resolution of the two satellites' laser altimeters.
Preliminary Modeling Study of a Vertical Evacuation Structure Site for the Aberdeen School District
(2020-02) Adams, L.M.; Gonzalez, F.I.; LeVeque, Randall J
A Maximum Considered Tsunami (MCT) scenario was developed for a magnitude 9 tsunamigenic earthquake on the Cascadia Subduction Zone. The development of this MCT scenario is compliant with our current understanding of the American Society of Civil Engineers (ASCE) Building Code 7 published in 2016, i.e., ASCE 7-16. The results of the numerical simulation support the design of a vertical evacuation structure (VES) as part of the new Stevens Elementary School in Aberdeen, WA. Estimates of key hazard design parameters at the site include seismic subsidence of -2.76 m, 75 years of sea level rise to 0.37 m above the current level, maximum flooding of 2.75 m, and maximum current speed of 1.2 m/s. The arrival times of the leading edge and crest of the first wave to arrive at the site are 80 and 91 minutes, respectively, but several waves of increasing amplitude follow; the largest wave arrives almost 4 hours after the earthquake to create the maximum flooding and hazardous tsunami waves may continue to arrive for several hours beyond the 6-hour simulation. Substantial Aberdeen land area will be lost due to permanent flooding at levels that vary twice a day from 0 m (no flooding) at MLW to a maximum of about 3 m at MHW, depending on the location. It must be kept in mind that the simulated MCT scenario is probabilistic in nature, a single realization of an event with an estimated 2,475-year mean recurrence interval, so that the results discussed in this report cannot be taken literally as an accurate, detailed prediction of what will happen; rather, valuable general guidance is provided on what may happen, but significant uncertainties exist in any seismic or tsunami model result.
South Pole Lake: ground-based ice-penetrating radar
(2020-03) Hills, Benjamin; Christianson, Knut; Holschuh, Nicholas
Modeling Study of a Proposed Vertical Evacuation Structure Site for the Shoalwater Bay Tribe Final Project Report
(2020-02) Adams, L. M.; González, F. I.; LeVeque, Randall J
A Maximum Considered Tsunami (MCT) scenario was developed that includes projected sea level rise of 0.47 m over 75 years and a magnitude 9 tsunamigenic earthquake on the Cascadia Subduction Zone; development of the scenario is compliant with our current understanding of the 2016 American Society of Civil Engineers (ASCE) Building Code 7, i.e., ASCE 7-16, and was reviewed by a SEFT Peer Review Team and Peer Review Advisory Panel for the project. The results of the numerical simulation support the design of a vertical evacuation structure, a tower located within the city of Tokeland, WA on land purchased by the Shoalwater Bay Indian Tribe. Estimates of key hazard design parameters at the site include 75 years of sea level rise to 0.47 m above the current level, seismic subsidence of -2.5 m, maximum flooding of 5 m and maximum current speed of 6.7 m/s, all referenced to mean high water (MHW). The arrival times of the leading edge and the maximum amplitude of the first wave to arrive at the site are 29 and 36 minutes, respectively. Hazardous tsunami waves continue to arrive for the 6 hours of the simulation and would likely continue for as many more. Most of the peninsula will be flooded twice daily at mean high water to a depth of 1-3 m for decades, assuming that post-seismic uplift eventually raises the land above mean high water.
Linking postglacial landscapes to glacier dynamics using swath radar at Thwaites Glacier, Antarctica - Supporting Data
(2019) Holschuh, Nicholas; Christianson, Knut; Paden, John; Alley, Richard; Anandakrishnan, Sridhar
This archive contains profile and gridded radar data referenced in the paper "Linking postglacial landscapes to glacier dynamics using swath radar at Thwaites Glacier, Antarctica", published in the journal Geology in 2019.
Thermal Weakening, Convergent Flow, and Vertical Heat Transport in the Northeast Greenland Ice Stream Shear Margins - Supporting Data
(2019-06-27) Holschuh, Nicholas; Lilien, David; Christianson, Knut
This archive contains radar data and model output referenced in the paper "Thermal Weakening, Convergent Flow, and Vertical Heat Transport in the Northeast Greenland Ice Stream Shear Margins", published in the journal Geophysical Research Letters in 2019.
Quantitative High-Resolution Re-Examination of a Hypothesized Ocean Shoreline in Cydonia Mensae on Mars
(2018-09-24) Sholes, Steven
Dataset in support of research submitted to the Journal of Geophysical Research: Planets.
Persistent Tracers of Historic Ice Flow in Glacial Stratigraphy near Kamb Ice Stream, West Antarctica - Supporting Data
(2018-08-05) Holschuh, Nicholas; Christianson, Knut; Conway, Howard; Jacobel, Robert; Welch, Brian
This archive contains radar data referenced in the paper "Persistent Tracers of Historic Ice Flow in Glacial Stratigraphy near Kamb Ice Stream, West Antarctica", published in the journal The Cryosphere in 2018.
Challenges and opportunities for research in tectonics: Understanding deformation and the processes that link Earth systems, from geologic time to human time. A community vision document submitted to the U.S. National Science Foundation.
(University of Washington, 2018) Huntington, K. W.; Klepeis, K. A.
Geoscience is an inherently interdisciplinary endeavor, and one of the most interdisciplinary geosciences is tectonics. Embracing experimental, observational, and theoretical perspectives, tectonics focuses on the interactions among various components of Earth and planetary systems as they evolve over many spatial and temporal dimensions. Many of the products of these interactions—from earthquakes, volcanic eruptions, tsunamis, and landslides to water, mineral and energy resources—have important human consequences. Thus, in addition to contributing to a deeper understanding of planetary dynamics, tectonics research routinely addresses issues essential to human societies. The distinctions between “pure science” and “applicationinspired” aspects of tectonics are rapidly blurring, and the time is ripe to re-visit our traditional definition of tectonics as a field within the geosciences and re-imagine it for the 21st Century. In doing so, we have an opportunity to identify newly emergent opportunities and the key technological and infrastructure requirements for breakthrough research. A year and a half of community-wide discussion of future research opportunities resulted in the identification of five “grand challenges” that will inspire tectonics research over the next decade and beyond: ü Understanding planetary evolution in four dimensions ü Understanding the dynamic interactions among Earth-surface processes and tectonics ü Understanding variations in rheology throughout the lithosphere ü Understanding fault zone behavior from Earth’s surface to the base of the lithosphere ü Meeting societal needs while advancing research in structural geology and tectonics This community vision extends beyond understanding the processes we can observe at Earth’s surface in the present day to explore planetary system evolution in four dimensions: over three spatial dimensions at scales ranging from nano to global, and across the fourth dimension of time over scales of seconds to billions of years.
Decoding ice sheet behavior using englacial layer slopes - Supporting Data
(Geophysical Research Letters - AGU, 2017-05-09) Holschuh, Nicholas
This archive contains radar data referenced in the paper "Decoding ice sheet behavior using englacial layer slopes", published in the journal Geophysical Research Letters.
Probabilistic Tsunami Hazard Assessment (PTHA) for Crescent City, CA
(2014-09-11) Gonzalez, Frank I.; LeVeque, Randall J; Adams, Loyce M.; Goldfinger, Chris; Priest, George R.; Wang, Kelin
This report builds on and supercedes Phase I of a demonstration Probabilistic Tsunami Hazard Assessment (PTHA) study of Crescent City, California [23], which developed an improved methodology for PTHA and associated products that addressed only tsunami flooding depth. The study documented in this report was originally conceived as a follow-on that simply extended Phase I products to include additional tsunami parameters associated with tsunami flow in particular, current speed and momentum flux. As this study was underway, however, it was reviewed by the California Probabilistic Tsunami Hazard Analysis Work Group (CA PTHA WG) [25] that included experts on various PTHA issues, most notably the critical issue of seismic source specification. Subsequently, the CA PTHA WG review concluded that the CSZ sources used in the Phase I work was not adequately consistent with the 2014 Update to the National Seismic Hazard Maps (NSHM) [54]. Consequently, an improved suite of CSZ sources had to be developed that was more consistent with the NSHM, as discussed in Section 7.6. As a consequence, the entire set of inundation model simulations had to be repeated and new PTHA flow depth products were developed. The results presented here thus supercede the results presented in the Phase I report [23]. Both Phase I [23] and this study were funded by BakerAECOM and motivated by FEMA’s desire to explore methods to improve products of the FEMA Risk Mapping, Assessment, and Planning (Risk MAP) Program. Here we briefly summarize the goals, deliverables, technical challenges, additional work, primary results and conclusions, and recommendations of this study.
Tsunami Hazard Assessment of the Ocosta School Site in Westport, WA
(2013-09-11) Gonzalez, Frank; LeVeque, Randall J; Adams, Loyce
The Westport Ocosta School District is proposing the construction of a new building to replace the current Ocosta Elementary School (Educational Service District 112, 2012). Since the Walsh et al. (2000) study, there have been significant advances in tsunami modeling and our understanding of potential CSZ earthquake events. Consequently, this study was commissioned and funded by the Washington Emergency Management Division to meet the need for an updated assessment of the tsunami hazard at the Ocosta School campus.
Tsunami Hazard Assessment of the Elementary School Berm Site in Long Beach, WA
(2013-04-27) Gonzalez, Frank; LeVeque, Randall J; Adams, Loyce

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