Tag: Thomas Giachetti

Investigating Greywater Filtration Capabilities of Pumice and Scoria from the Pacific Northwest

Presenter: Margery Price – Earth Sciences

Faculty Mentor(s): Thomas Giachetti

Session: (In-Person) Poster Presentation

Graywater (wastewater produced by bathing, washing, and other domestic water uses) contains particles that can be removed by filtration. With treatment, it can be reused for tasks such as irrigation or street cleaning. Pumice and scoria, highly porous volcanic rocks, are optimal filtration media; they have both high external and internal surface area due to their tortuous networks of connected pores. This project investigates the physical characteristics of pumices and scoriae that most impact their efficacy as filter materials by testing interactions between the rocks and graywater. Samples of pumice and scoria from Oregon volcanoes are measured using a Particle Analyzer, a high precision scale, and a helium pycnometer to find mass, volume, packing fraction, and total and connected porosity. Graywater is created using conventional household cleaning and personal care products, then characterized for pH, turbidity, TDS, and conductivity. Lastly, static absorption experiments examine the interactions between pumice and scoria with both tap water and graywater when submerged. Preliminary results show that pumice and scoria systems of the same sizes absorb similar volumes of water, despite having different porosities. Scoria offers more area of interaction with water on its external surfaces, but pumice contains more available surface area within the particles. More work needs to be done investigating which of these parameters results in better filtration of graywater.

Decompression Experiments of the Mono Craters Eruptions of 1340 C.E.

Presenter(s): Eamonn Needham − Earth Sciences

Faculty Mentor(s): Jim Watkins, Thomas Giachetti

Poster 4

Research Area: Earth Sciences (Geology)

Funding: UROP mini grant

The Mono Craters, California eruptions of 1340 C.E. were a series of eruptions that produced relatively texturally homogeneous deposits, with the exception of the first bed. The initial eruptive deposits differ from later deposits in
the relative abundance of obsidian pyroclasts (quenched magma), volatiles (H2O and CO2), and microlites (minerals <100μm). These textural differences between Bed 1 and the other beds remain unexplained, but may be due to changes in decompression rates. To test the decompression rate hypothesis, a sample of synthetic Mono obsidian was run in a cold seal pressure vessel at eruptive conditions. The sample was kept at 850°C and 60 MPa for 2.5 days, and then was decompressed isothermally at a rate of 0.001 MPa/s until it reached 5 MPa. Following rapid quench, bubble number density and microlite number density were determined from scanning electron microscope images. In the future, more of these experiments will be run at different decompression rates, to see which decompression rate best match the textures of the Bed 1 samples. The calculated decompression rate will be compared to decompression rates of later deposits which were calculated in other studies using volatile concentrations. If Bed 1 has a different decompression rate than the later beds, this could explain the textural differences, and can be used to look at how the eruption initiated and progressed. This research could have implications for the ongoing debate of eruptive style transitions from explosive to effusive, which in turn will inform hazard mitigation for volcanoes exhibiting this behavior.

Examining patterns in volume and spatial occurrence of cinder cones at Newberry Volcano, Oregon

Presenter(s): Hannah Kruse

Faculty Mentor(s): Thomas Giachetti

Poster 40

Session: Sciences

Newberry Volcano is a large quaternary shield-shape volcano that sits 60 km to the east of the Cascade Volcanic Arc. It is the second most voluminous volcano in the Cascades (~500 km3) and has more than 400 satellite vents dotting its flanks, some over 20 km away from the central caldera. Many of these vents sport cinder cones that postdate the last caldera-forming eruption and are most common to the north and south of the caldera, less so to the east and rare to the west, drawing a crescent across the landscape. This is an unusually high number of satellite vents for any volcano to exhibit, and in an unusual geographic pattern. These vents may tell us something unique about the internal structure of Newberry’s magma chamber and plumbing system.

Using geological maps and Digital Elevation Models, my research focuses on gathering and analyzing data that describe the spatial and temporal occurrence, size, volume, and chemical composition of Newberry’s cinder cones to find any relationships that exist between them and the central caldera, other local geologic features, and each other. Newberry provides a unique opportunity in its abundance and preservation of somewhat recent vents to explore these. Newberry is currently designated as a “Very High Threat” by the U.S. Geological Survey. Understanding its architecture and eruptive patterns is therefore essential to hazard assessment, preparedness, and mitigation.

Relating Pumice Permeability to Vesicle Attributes using 3D Printed Models

Presenter(s): Frederick Ede

Faculty Mentor(s): Thomas Giachetti

Poster 46

Session: Sciences

Pumice is a highly porous rock composed of volcanic glass bearing dense and complex networks of vesicles—bubbles preserved in solid rock resulting from the exsolution of volatiles such as water and carbon dioxide from the magmatic melt during its ascent to the surface. These vesicles often become interconnected, rendering the magma permeable to buoyant gas which escapes into the host rock or the atmosphere. This process, which is known as outgassing, reduces the overpressure in the magma and may prevent fragmentation and explosive eruption. How permeability varies depends on the size, shape, and abundance of vesicles and fractures. The goal of my project is to analyze the physical properties of 3D printed pumice models. While some data can be obtained from virtual pumice models, having physical representations of the tortuous, constricting passages that render pumice permeable will lead to a better understanding of real-world pumice permeability. Studying the properties of volcanic products grants insight into the eruption process. Understanding how vesicle networks develop and how they impact eruption style will lead to enhanced volcanic hazard prediction and mitigation. To aid in the effort of better understanding the effects that developing vesicle networks have on the eruption process of a volcano, I will establish functional relationships between pumice permeability and vesicle and fracture characteristics such as number density, size, and shape.