Ocean conveyor belt circulation is conceptually foundational in oceanographic education. It is the idea that oceans slowly overturn through the movement of deep water toward the equator and surface water toward the poles. Introductory courses often spend the majority of a semester building the skills required to understand the basics of this theory. Ocean circulation is also typically covered through multiple courses to build upon its complexity through different study lenses. The multi-dimensional concept of ocean circulation is commonly conveyed through 2D diagrams and animations rather than presenting ideas in a 3D space that allows students to form connections between theory and physical space. Students were asked to interact with a 3D printed model that recreates circulation diagrams by connecting cross-sections of oceanographic data to specific locations on the model. Furthermore, students were asked to describe how perturbations to surface conditions could change ocean stratification and how water circulates based on its temperature and salinity. Previous 3D printing experience allowed us to expand students’ experiences while struggling to parse these interdisciplinary oceanographic topics. Here we show that using a physical model in teaching thermohaline circulation enhances the speed and depth at which students understand ocean circulation compared to the traditional 2D approach. Surveys were given to assess students’ understanding of the driving factors behind thermohaline circulation prior to and after interacting with the model. Preliminary results show that students can better connect oceanographic concepts taught in lectures to data and locations essential to ocean circulation after completing exercises that ask them to interact with the model. We anticipate students to exhibit further proficiency in concepts related to ocean circulation after interacting with this model. We also expect to find that students will express a desire to see the utilization of similar models in more of their core oceanography courses.

The deformation processes in the brittle-ductile transition region are poorly constrained and critical to understanding both the magnitude of earthquakes within the subduction seismogenic zone, and slow slip and tremor downdip of this region. Here we present field observations and microstructural data in the form of photomicrographs, thin-section scale x-ray maps and electron backscatter diffraction (EBSD) to constrain the rheology of a paleosubduction interface in the Central Alps during deformation and fluid-rock interaction. We studied three samples across a 10 meter transect within the lowest 10 meters of the overring Austroalpine plate at the contact with the Penninic subduction plate shear zone. Our granodiorite samples are exhumed from paleodepths of 30-35 km. Cataclasites, microfractures, and crack-seal quartz ± calcite veins are evidence of brittle deformation while a ductile foliation fabric indicates viscous deformation at conditions of 400-430ºC & 0.80-0.95 GPa. EBSD data shows progressive increase in viscous deformation and mineralogic changes closer to the contact. As the samples progress towards the shear zone the crystallographic preferred orientation and grain misorientation of quartz and albite decreases suggesting the controlling deformation process changes from dislocation creep to diffusion creep due to pinning of the albite and quartz by phengite. This coincides with progressive fluid-rock modification observed in photomicrographs and chemical x-ray maps. We observe a decrease in albite replaced by an increase in quartz and phengite across the three samples. The breakdown of albite, and its replacement with more water rich minerals like phengite, the quartz +/- calcite veins, and the progressive shift from dislocation to fluid-aided diffusive mechanisms demonstrates increased fluid-rich interactions nearer to the plate interface contact. Increased fluid-rock interaction impacts the viscous deformation mechanisms and strength of these rocks. Diffusion creep occurs in low stress environments, suggesting that fluid- rock interactions lead to a low stress environment below the locked seismogenic zone.

A novel freshwater methane seep with unique physics and chemistry was discovered off the Oregon coast in 2014. This seep, called Pythia’s Oasis, is located ~20 km east from where the Juan de Fuca plate subducts beneath the North American plate along the Cascadia Margin. Studying microorganisms from deep within subduction zones is difficult and requires deep-sea drilling expeditions that can disrupt the ecosystem. Recent analyses of Pythia’s Oasis fluids suggests that they likely originate from high temperatures deep within the Cascadia Margin, providing a window into the region where deep subduction-zone fluids are formed. The Pythias’s plume has a vent-orifice temperature of 12.08ËšC, ~3 times warmer than background seawater and is characterized by low-salinity and methane-saturated fluids. Nothing is currently known about the microorganisms that inhabit this type of system. In August of 2021, the deep-sea remotely operated vehicle Jason collected 5 L of fluid emanating from the Pythia’s Oasis’s orifice. The goal of this project is to extract and sequence community-genomic DNA to identify the dominant taxa present in this system and to elucidate the diversity of functions present. The resulting metagenomic data will be analyzed using established bioinformatic tools that can assess diversity and genetic potential. Results of this research will provide new insights into the chemical and biological conditions within the subsurface of the Cascadia Margin and similar systems in the deep subsurface.

The North Arch Volcanic Field lies north of O’ahu, covering 24,000 km² of seafloor. It is a part of the greater Hawai’ian Arch, a region of uplifted seafloor surrounding the Hawai'ian hotspot. The North Arch is a fairly recent discovery, with little known about it. It is a product of recent basaltic volcanism, the mechanism of which is not understood. The magnetic minerals found in basalts retain the signature of the Earth’s magnetic field at the time they cooled. Thus, basaltic lava flows generally have high remnant magnetization, distinguishing them from the surrounding, weakly-magnetized sediments. My objective was to use a magnetometer to assess the feasibility of using magnetic anomalies to determine the thickness of lava flows in the southern North Arch. On board the R/V Thomas G. Thompson, a sub-bottom profiler and multibeam sonar system were used to resolve lava flow boundaries while I collected data with a towed magnetometer. The ship followed 5 east-west track lines before heading north-west along an inferred rift on the seafloor, then west to exit the field. I obtained magnetic anomalies by correcting the raw magnetic data with the International Geomagnetic Reference Field and a time series from Honolulu’s magnetic observatory. I then used a modeling program to compare observed anomalies with those predicted for lava flows of varying thicknesses. A modeled flow along the northmost track line yielded a flow maximum thickness of 50 m, thinning to 5 km towards the east edge of the field. The results show that the magnetic anomaly produced by these flows was strong enough to be detected and yielded flow thicknesses of tens of meters that are consistent with other observations. This research demonstrates that magnetometry is an effective tool for studying the North Arch Volcanic Field and could be used on other submarine volcanic fields as well.

Freshwater wetlands are the largest natural source of methane, a powerful greenhouse gas (GHG), to the atmosphere. However, the mechanisms and magnitude of wetland methane (CH₄) emissions are not well understood. There is significant variability of flux estimates between field sites and a lack of agreement between top-down and bottom-up estimations of methane flux, indicating a high level of uncertainty. This study provides the first estimation of aquatic methane flux in the Union Bay Natural Area (UBNA). This site can be categorized as a freshwater wetland and is an urban site that is adjacent to a former landfill. We hypothesize that the flux will be dominated by ebullition (bubble released) emissions and that the total emissions will decrease as depth increases. To measure the total CH₄ flux, we measured diffusive emissions using a flux chamber and LGR portable greenhouse gas analyzer and ebullition emissions with bubble traps that were left in the field site for 48 hours. In addition to these measurements we collected water parameter measurements using an Exo sonde and dissolved gas samples at each diffusive sampling location. With this data, we were able to calculate the measured CH₄ flux and model the flux so that the two values could be compared. This study indicates the spatial variability and depth-dependent patterns of methane flux in the UBNA. There are multiple possible extensions of the research. If more sampling campaigns were conducted throughout the year, the data could be used to describe temporal variability in flux. Additionally, if gas samples are collected from the ventilation systems on the landfill, an isotopic analysis could reveal the percentage of methane emissions that can be attributed to decomposition in the landfill.

Although the dominant forcing for earthquakes is plate tectonics, a wide variety of other processes have also been shown to modulate the tectonic release of elastic strain such as glacial mass changes, reservoir impoundment, and monsoonal loading. Here, we examine the relationship between surface mass loading and seismicity. We examine data from the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On (GRACE-FO) that have been monitoring global gravity changes from 2002 to 2022 and compare this record to the USGS earthquake catalog with magnitudes greater than 5.4 during the same time period. We compare the distribution of the surface mass loading during all time periods to the distribution of the surface mass loading during time periods with an earthquake occurrence. We use Bayes’ theorem to calculate the relative conditional probability of an earthquake occurrence given the surface loading. We use the Kolmogorov-Smirnov and Cramér-von Mises statistical tests to confirm that the surface mass load during periods with an earthquake are significantly different than the background. We conclude that there is a higher relative probability for earthquakes to occur during periods of large surface mass loading and unloading. The existence of surface load induced events suggest novel interactions between cascading hazards, such as earthquakes and landslides. Our analysis provides evidence for the hypothesis suggesting that cascading solid Earth and Earth-surficial hazards exhibit two-way coupling.

Community composition and structure of modern benthic foraminiferal assemblages are commonly used as indicators of integrative water quality. The San Juan Archipelago is a tidally mixed estuarine environment located in the Salish Sea. This is an oceanographically complex area due to ocean input from the Strait of Juan de Fuca and estuarine input from the Fraser River. To assess the feasibility of using foraminifera as water quality indicators, foraminiferal assemblages from four oceanographically distinct locations in the San Juan Archipelago were collected and subsequently identified to pair water conditions with associated differences in assemblage. I carried out a survey of foraminiferal tests from Rosario Strait, Strait of Juan de Fuca, and San Juan Channel. Density of the number of tests decreased in high current environments and water-column stratification had no impact on assemblage. Abundance of Lobatula lobatula and Rotalinoides gaimardii were significantly correlated with oxygen, temperature, salinity, and nitrate. Depth and individual water conditions were observed to impact diversity of foraminiferal assemblage more than stratification. Foraminifera are incredibly resilient and present in most sediments of the San Juan Archipelago allowing foraminiferal assemblage to be used as a tool for water quality assessment in the San Juan Archipelago based on the abundance of species like L. lobatula and R. gaimardii.