Contributors:Simpson, Chase, Sorour, Sameh, Abdel-Rahim, Ahmed, Hurwitz, David S., Parrish, Christopher
Contributors:Cunitz, Bryan W, Bailey, Michael R, Wang, Yak-Nam, Maxwell, Adam D, Khokhlova, Vera A, Ghanem, Mohamed A, Sapozhnikov, Oleg A
Video recordings data to accompany the article "Noninvasive acoustic manipulation in a living body."
Holocene landslides and marine terraces at Rialto Beach, on the Olympic coast of Washington state, may provide clues about the response of the Pacific coastline and adjacent hillslopes to Cascadia subduction zone (CSZ) earthquake activity. This study uses seven 14C samples from four distinct locations within a low-elevation marine terrace at Rialto Beach, WA to date landslides and constrain age of formation of the terrace. Two distinct landslides have been explored in detail: landslide 1 that occurred 800 years cal BP, and landslide 3, that occurred 150-300 years cal BP. The causes and triggers of these slope failure events were explored with new detailed field mapping and timing constraints. Observed landslide evidence includes hillslope geomorphology, soil composition of hillslopes, low-elevation marine terrace composition, and presence of slickenside bedrock-colluvium contacts within a drainage system. On landslide 1 I found a buttress unconformity on the hillslope containing interglacial peat and organic soil layer dated >48-27.5 cal ka, causing extensive zones of perching water that increases pore pressure and lowers slope stability. These geological layers are assumed to span the Rialto hillslope region. Dendrochronology to determine the age of trees on landslide 1 suggests that this slope was partially denuded during an intense winter storm in 1921 AD, potentially causing slope instability. Landslide 3, 150-300 yrs cal BP sits atop the potentially uplifted marine terrace which contains beach deposits older than 500-600 years cal BP. Dating suggests that the slide and uplift may be coseismic with the 1700 AD (270 BP) Cascadia subduction zone rupture. This study adds constraining dates of two distinct landslides that sit on top of the low elevation marine terrace, contributing to studies of coseismic uplift and landsliding on the Olympic coast.
Loess is a fine-grained floury material carried by wind. The properties of loess are
important for infrastructure, agriculture, and construction planning in areas where it is
abundant. Eastern Washington is one such location where loess hills dominate the
landscape. Past studies have established the geologic origins of loess in Eastern
Washington on a broad regional scale. These studies established that paleowinds carried
the loess Northeast and that gran size decreases downwind. Naturally, I set out to ask if
the paleowind direction and subsequent decrease in grain size can be detected over a
smaller two county area. To answer this, I collected 27 samples of loess in Adams and
Lincoln counties to determine its index properties and look for regional patterns in grain
size. I analyzed grain size, moisture content, and Atterberg limits. Then I evaluated the
results in a geographic information system. I found that paleowind influence can be found
in the grain size and properties of the loess within Adams and Lincoln counties. The
results of my study provide insight into the general characteristics of loess index
properties in parts of Eastern Washington and confirm the results from previous work.
The Port Gamble SíKlallam Tribe (PGST) relies on coastal resources for recreation, cultural enrichment, spiritual enhancement, and food. Shoreline change and extreme water levels associated with climate change will impact the future of the PGST. As part of their effort to create a coastal management plan, PGST contracted with our project team to assess geologic aspects of coastal risk and provide recommendations for future monitoring.
There is limited information on coastal geomorphology, sediment transportation, and accurate water levels for the PGST coast (Ladd et al., 2016; McCollum et al., 2016). This report addresses shoreline changes, extreme water levels, and coastal hazards associated with climate change along the PGST coastline. I designed a sediment transport monitoring system and conducted water level measurement and analyses.
For the first Phase of this project, I assessed historical coastal bluff and shoreline changes using aerial photographs, historical maps and photographs, shoreline topographic surveys, LiDAR analysis, and time-lapse photography. I established shoreline transects for future monitoring of the PGST shoreline and collected baseline data. Using historical T-sheet survey data with modern LiDAR, I found the PGST bluff erosion rates to be less than 3.7 ± 2.8 in/yr over a 162-yr period from 1856 to 2018, with the highest rate along the Tribal Center bluff. Overall, the beach face appears to be relatively stable with little evidence of change from our GNSS beach transect surveys.
To evaluate extreme water levels, I collected water level data along the PGST coast and compared our local water level measurements to long-term water level records at Port Townsend and Seattle. Water level data at PGST suggest that using longer water level records from Seattle and Port Townsend would reliably predict flood magnitude and frequency at PGST. Our data show bluffs currently undergo frequent interaction with sea water. During our study, time-lapse photography showed small (< 1 ft) waves with limited wave run-up. However, while not entirely common along the PGST coastline, the combination of larger storm events with high tides may cause flooding of Point Julia and increase bluff erosion rates.
Lastly, I assessed the response of coastal flooding to climate change along the PGST coastline. Extreme water levels will flood most of Point Julia under different climate change scenarios. We created a series of inundation maps at Point Julia based on recent sea level rise projections for the area (Miller et al., 2018). Climate change and sea level rise will impact the coastline and how the tribe interacts with it.
The development of detailed sediment budgets and shoreline change models requires long-term, high-resolution datasets. While our data provide a baseline, continued study and additional data are recommended to make informed coastal management decisions. I recommend performing frequent (2-3 years, seasonally, or event-aligned) repeat surveys of the established shoreline transects. I recommend yearly surveying for transects in areas of highest erosion (i.e. near the Tribal Center). Flooding and bluff erosion may be mitigated by projects which support large woody debris and increased sediment on beaches. Coastal inundation maps may be helpful for planning and management strategies, considering the time frame and likelihood of each scenario.
I address the large-scale stability and potential past and future triggers of the Lost Lake
Landslide on Vashon Island, one of the largest mapped landslides in the Puget Lowland. I focus
on three landslide triggers; groundwater fluctuation, the Seattle Fault Zone and the Tacoma Fault
Zone and identify the most likely trigger. No previous work has analyzed the trigger, age, or
stability of the slope. Using an end member approach, I calculate the factor of safety and seismic
critical acceleration using a two-dimensional limit equilibrium model for three different Lost
Lake Landslide scenarios. Two scenarios are a reconstruction of potential past failure and one
scenario is a future failure of the modern slope. Using USGS ShakeMaps I compare modeled
Seattle Fault Zone and Tacoma Fault Zone peak ground accelerations with calculated critical
accelerations from this study. I find that significant groundwater fluctuations have a surprisingly
low influence on large-scale slope stability. Additionally, shaking from either a Seattle Fault
Zone or Tacoma Fault Zone earthquake could have triggered the Lost Lake landslide. A Tacoma
Fault Zone earthquake is a more likely trigger due to its greater exceedance of the required
critical acceleration to cause a slope failure. My results indicate that large magnitude crustal
earthquakes can potentially trigger extremely large landslides in the Puget Lowland. As a first
order assessment, factor of safety and critical acceleration analysis can potentially identify other
large co-seismic landslides in the Puget Lowland.
The physical mechanisms that cause slope failure involving the Lawton Clay in the Puget Lowland have been well studied; however, the physio-chemical mechanisms, specifically acidic pore fluid are poorly understood. This study attempts to quantify the effect of pore fluid acidity on the Lawton Clay’s plasticity through Atterberg Limit tests. I conducted multiple runs of the liquid limit and plastic limit tests on rehydrated, homogenized samples of Lawton Clay with acidic solutions mimicking the composition of acid rain in the Seattle area at a pH range of 3.5 to 7. My results show a trend of increasing and then decreasing liquid limit with increasing acidity. This trend is best explained by changes in the thickness of the double diffuse layer and clay minerals’ ability to attract water to its surface. The changes in Atterberg Limits can be used as a proxy for changes in strength. The liquid limit results suggest that variations in pore fluid pH could affect the strength of the Lawton Clay and hence be an important variable in slope stability.
Tsunami deposits from an earthquake on the Seattle fault have been found around
the Puget Sound area. Tsunami modeling has been conducted in Puget Sound with the
Seattle fault as the initiating event, however published modeling efforts have not
investigated the effects of an event from the Seattle fault on the Lake Washington
area. The Seattle fault crosses Lake Washington extending east towards Lake Sammamish,
and a tsunami generated from this fault could create hazardous conditions along the
lake’s shorelines. The parameters of the Lake Washington section of the Seattle fault
are applied to create deformation files modeling potential tsunami waves generated from
a fault rupture. Four simulations are run with the modern-day lake level and again with
the pre-ship canal lake level using the open source software GeoClaw. These eight
simulations are analyzed to determine which fault parameters produce a wave that inundates
the shoreline. A scenario modeling a 10-meter slip at a depth of 1-km that uses the
pre-ship canal lake level and a four-hour runtime determines the extent of inundation
and locates potential areas for tsunami deposits. These results show that the shoreline
is inundated four times over the first four hours after the earthquake, with maximum
tsunami wave heights of 2 m to nearly 4 m arriving within minutes to tens of minutes of
the fault rupture. I identify seven low-lying areas susceptible to inundation and suggest
three sites for paleotsunami investigation as a test for these models. More extensive
modeling of different scenarios and fault parameters is needed to understand the range of
possible or likely inundation from a tsunami wave in Lake Washington triggered from the
The goal of this research is to investigate geochemical factors on arsenic removal from groundwater in a groundwater treatment cell. The treatment cell is near Metaline Falls, WA, and is operated by Geosyntec Consultants. Using PHREEQ-C, a program developed by the USGS for chemical modeling, I determined which adsorptive media will remove the most arsenic under site conditions, which ions inhibit or encourage arsenic adsorption, and which ions have the potential to remove arsenic through co-precipitation.
The groundwater samples collected from the site were taken to the UW SEFS Analytical Lab for inductively coupled plasma mass spectrometry (ICP-MS) to determine the concentrations of each ion present in the groundwater. These lab results were used for the model validation initial conditions. Historical data collected at the site by Geosyntec was compiled into a database for statistical analysis, which identified conductivity, a proxy for ionic strength, and manganese in solution as two main factors influencing arsenic removal. These factors were further studied using PHREEQ-C.
From the modeling results I found that titanium oxide media, particularly MetasorbG manufactured by Graver Technologies, to be the most efficient media at removing arsenic via adsorption. I found that phosphate in the groundwater plays the largest role in inhibiting arsenic adsorption by directly competing with arsenate for surface sites. Conductivity, or ionic strength, will reduce adsorption rates upgradient of the treatment cell and lead to higher arsenic concentrations being delivered to the cell. And, finally, I determined that arsenic is oxidized by manganese oxides and will readily precipitate with manganese ions in high pH conditions, which are typically found upgradient of the treatment cell.
For further study, I recommend monitoring phosphate levels in the treatment cell, determining residence time of the water in the treatment cell, performing XRD or FTIR analysis on gravel inside the treatment cell to determine what minerals are precipitating, and starting two batch-scale trials with titanium oxide and manganese oxide media.
Geomorphic evaluation of the northeastern Kittitas Valley and Hog Ranch-Naneum Anticline (HRNA) region provides new insight into the recent deformation and uplift by Quaternary faults along the northern range front of Kittitas Valley. I conducted LiDAR and landform mapping as well as a suite of geomorphic analyses to assess recent faulting in northeastern Kittitas Valley potentially linked to Quaternary deformation of the HRNA area. Upon generation of normalized channel steepness (Ksn) maps, the northeastern basin front was identified as a starting point for additional geomorphic analyses, LiDAR mapping and focused field truthing/mapping. I identified a flight of six strath river terraces near the entrance of Coleman Creek into Kittitas Valley. I also identified knickpoints and knickzones along the southern basin front which I was able to correlate to the knickpoint groupings along Coleman Creek. Based on geomorphic evidence and LiDAR mapping two fault scarps were identified; the Facet fault located at the base of the range front and the Dead Coyote fault located ~2 km south of the range front. Regional geologic mapping and aeromagnetic data suggests that initial tectonic uplift along the HRNA predates the Yakima folds. Exact ages of newly identified faults are unknown. The presence of uplifted strath surfaces within Kittitas Valley suggests a more recent deformation history based on the premise that the landscape within the fold province and HRNA was reset to relatively level relief ~15.6 Ma following the emplacement of the Grand Ronde Basalt member of the CRBG; deformation seems to have continued into the Quaternary (Kelsey et al., 2017 and Reidel, 1989).