M.S. - Earth and Planetary Sciences

Permanent URI for this collectionhttps://hdl.handle.net/10125/66122

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Analyzing noise properties of cabled broadband ocean-bottom seismometers for the application of smart sea cable in the Vanuatu - New Caledonia subduction zone
(University of Hawai'i at Manoa, 2025) Maso, Elliona; Janiszewski, Helen HAJ; Earth and Planetary Sciences
The Vanuatu subduction zone (VSZ), also known as the New Hebrides Trench, is a tectonically active zone characterized by a high frequency of earthquakes with magnitudes greater than 5.5 and volcanic activity. Earthquakes with epicenters ranging from shallow (~10 km) to deep (~700 km) cluster beneath the VSZ, with limited opportunity for earthquake and tsunami early warnings. Recent initiatives aim to install geophysical and oceanographic monitoring equipment on a seafloor cable extending from New Caledonia to Vanuatu using Science Monitoring and Reliable Telecommunications (SMART) cable technology to mitigate these hazards. These oceanographic sensors would measure temperature, pressure, and seismic acceleration to monitor climate and ocean observations, sea-level changes, and provide reliable geophysical measurements of earthquakes and fault properties. However, seismic waves recorded by seafloor instruments may have tilt and compliance noise. Using the Automated Tilt and Compliance Removal (ATaCR) method, these noise properties are analyzed from broadband ocean bottom seismometers (BBOBS) from a similar cabled system, the Ocean Observatory Initiative offshore the Cascadia subduction zone, to establish a baseline for comparison with future SMART cable installations in subduction zones. Understanding these noise parameters, we can estimate the likely output signals from different instrument types at various water depths, for future designs such as those employed by the Vanuatu-New Caledonia’s TAMTAM SMART system.
Mantle, crust, and sediment structure near the Hawaiian ridge using seismic shear waves
(University of Hawai'i at Manoa, 2025) Cryder, Morgan Elizabeth; Dunn, Robert A.; Earth and Planetary Sciences
The Hawaiian Ridge represents a complex intra-plate volcanic system formed by plume or hotspot-related mantle melts rising through the oceanic lithosphere, constructing volcanic edifices on the Pacific Plate. At Ka‘ena Ridge, a submarine volcanic edifice west of O‘ahu, the seafloor rises from ~5 km to less than 2 km below sea level, while surrounding flexural moats extend to depths of ~6 km due to lithospheric loading. We use active-source seismic data to construct 2-D S-wave (Vs) velocity-depth and Vp⁄Vs models along a wide-angle seismic profile crossing Ka‘ena Ridge. The velocity models reveal a typical Pacific oceanic crustal structure, with a thin sub-seafloor low-velocity layer (< 2.3 km/s; seismic Layer 1) characteristic of volcaniclastic and oceanic sediments, a thicker low-velocity layer (2.5–3.4 km/s; seismic Layer 2) thought to be the upper oceanic crust composed of dikes and lava flows, and a deeper high-velocity layer (3.5–4.0 km/s; seismic Layer 3), associated with intrusive gabbroic rocks. Relatively high Vp⁄Vs values (1.85–1.91) are recorded in some areas of the upper crust, indicative of increased porosity and fluid-filled cracks. Below the Moho, Vs values range from 4.5 to 4.8 km/s, while Vp⁄Vs decreases to 1.69–1.72 along most of the seismic line, likely reflecting an increase in dry olivine content in the uppermost mantle with no strong indication of an abundance of serpentinite or underplating occurring. Thus, we find no far-reaching effects on oceanic lithosphere other than the flexure from the seamount itself.
Investigating groundwater flow and quality in lahaina beaches affected by the 2023 Maui wildfire
(University of Hawai'i at Manoa, 2025) Lopez, Edward Peter; Geng, Xiaolong; Dulai, Henrietta; Earth and Planetary Sciences
On August 8, 2023, a devastating wildfire burned through Lāhainā, Maui. This major wildfire’s destruction introduced the risk of groundwater contamination from structure fires and boat storage damage in the nearby vicinity, leading to the potential for large amounts of chemicals (i.e. solvents, paint and oils) to seep into the ground. These contaminants may be detrimental to the long-term health of Lāhainā’s environment and community, and this study addresses their potential transport pathways with groundwater flow. In this study we developed a high-resolution, physics-based groundwater model to quantify coastal groundwater dynamics (flow, salinity, and water levels) in a Lāhainā beach affected by the wildfire, and to investigate the pathways and persistence of contaminants in Lāhainā beach environments. The model is further calibrated and validated based on field measurements of water levels and salinity. The study site is focused on a southern Lāhainā beach, where two transects were installed on the beach, perpendicular to the shoreline, one consisting of four piezometer wells, and the other of six multiport wells. The measurements from these wells, along with the analysis of seawater samples, are used as inputs for the groundwater model. The combined field measurements and groundwater modeling provide an understanding of potential pathways and the persistence of contaminants from the wildfires in Lāhainā’s coastal beach environments. These findings can provide insights into assessing the vulnerability and resilience of coastal aquifer systems to wildfire induced contamination, better preparing the development of effective mitigation strategies for affected communities.
Olivine trace elements as evidence for recycled oceanic crust and possible pyroxenite destruction beneath the Southern East Pacific Rise (SEPR)
(University of Hawai'i at Manoa, 2024) Chien, Annie; Jiang, Peng; Earth and Planetary Sciences
Lavas from the 13°S to 23°S Southern East Pacific Rise (SEPR) exhibit significant compositional heterogeneity both near and on the ridge axis, as well as at the off-axis Rano Rahi Seamounts and the west-northwest trending Pukapuka Ridge. These variations have been linked to ‘plume-like’ materials or ‘entrained mantle heterogeneity.’ However, it remains unclear whether this heterogeneity was caused by recycled oceanic crust (ROC) or the presence of pyroxenite lithology beneath the SEPR. In this study, we examine textures and geochemical (major, minor, and trace element) compositions of olivine phenocrysts from lavas from representative SEPR regions, via integrated EPMA and LA-ICP-MS techniques. Our analyses reveal high and low-Ni (nickel) abundances versus forsterite contents (Fo (mol.%)) trends that correspond to end-member melts fractional crystallization (FC) under low pressures (~0.1 GPa and lower) and high pressures (up to 1.5 GPa) based on Petrolog3 FC modeling. Additionally, low Ca concentrations (~1500 down to ~500 ppm), found exclusively in reversely zoned olivine cores are proposed to reflect deep-sourced, Ca-depleted melts derived from ROC-metasomatized mantle. These melts experienced high-pressure FC (up to 1.5 GPa), with high initial volatile content (up to ~1 wt.% H2O) under oxidized conditions (QFM+2). Multiple first row transition element ratios such as 100*Mn/Fe (~1.4 to ~1.8), 10000*Zn/Fe (~5 to ~15) and Mn/Zn (>14) show restricted variations that preclude a Cpx-Garnet dominant pyroxenite lithology and supports a peridotite lithology. However, the apparent absence of pyroxenite despite evidence of ROC involvement poses a paradox. This inconsistency can be explained by a possible "pyroxenite destruction" process, wherein ROC and its derived pyroxenite lithology have been fully consumed (remelted), leaving behind elemental and isotopic signatures of ROC (or ‘plume-like’ materials) without retaining pyroxenite lithology. These results shed light on the complex dynamics of mantle-crust interactions beneath the SEPR and suggest that ROC can impact mantle composition without the permanent retention of pyroxenite. Further investigation is needed to explore scale and magnitude of ROC components and pyroxenite preservation or destruction beneath the SEPR (and other mid-ocean ridge settings as well as mantle plume regions) as attempts to understand deep ROC role in affecting global-scale mantle chemical and lithologic heterogeneity.
CHARACTERIZING THE TEMPERATURE AND HYDROLOGICAL DYNAMICS OF THE MĀNOA STREAM
(University of Hawai'i at Manoa, 2024) Pantaleo, Hailey Rose; Dulai, Henrietta; Earth and Planetary Sciences
Climate change has far-reaching consequences for hydrogeological dynamics, including shifts in stream temperatures. Urbanization and land use change further alter stream conditions, with stormwater runoff from impervious surfaces contributing to rapid temperature fluctuations and removal of riparian vegetation leading to smaller temperature buffering. Additionally, changing precipitation patterns will affect surface runoff and groundwater contributions changing stream dynamics. The purpose of this study was to investigate which principal hydrological parameters influence the temperature of the Mānoa Stream. Principal variables measured included baseflow (quantified via discharge data, FINIFLUX radon modeling, stable isotopes, groundwater contaminant testing, and nitrogen), hyporheic flow (analyzed via electrical resistivity), precipitation (quantified via stable isotopes and direct collection records), canopy cover (observed as percent of coverage), stream bed/urbanization impact (quantified as natural versus constructed reaches and local population density), and season/date/time. Results indicate that baseflow contributions to the stream vary by season and stream reach but are not strongly linked to temperature changes. Precipitation may influence the isotopic composition of the stream heavily and temporarily and was primarily found to moderate stream temperature toward the stream average temperature. Canopy coverage, urbanization impact, and season/time correlate the most with recorded temperature trends, indicating the combination of these three parameters inflicting the strongest influence on stream temperature. These results suggest that Honolulu urbanization will have a strong control on the health of the stream in the future, likely to be exacerbated by climate change impacts.
Building an Understanding of Human-Water Resource Relationships through Community Engagement in Haʻikū and Huelo, HI
(University of Hawai'i at Manoa, 2024) Bees, Brandon Thomas; Shuler, Christopher; Earth and Planetary Sciences
This community-funded project is in support of the Haʻikū and Huelo residents that are impacted by limitations in, and decreasing quality of their drinking water sources. In the study area, many homes are not served by the County water system, and thus rely on private wells, springs, or rain catchment. The potential for future water development in northeast Maui, Hawaiʻi, causes concern for residents reliant on private ground or surface water sources. The vulnerability of water resources to overexploitation may cause negative impacts on both the water availability and cultural practices in this region. By supporting local residents in developing a better understanding of aquifer characteristics and response to stresses, such as decreased rainfall, or increased withdrawal rate, this work aims to increase community capacity and boost future water resilience. Increased knowledge of the hydrological connections that exist throughout the aquifer will yield insights into how future water withdrawals may impact current water levels and uses. Here, we use analysis of water isotopes (²H and ¹⁸O) in groundwater, surface water and precipitation, as well as major ion composition to elucidate connectivity between surface water and groundwater in the study region. We also applied an existing MODFLOW model to examine the impacts of a set of hypothetical production wells at different pumping rates to simulate how current wells may be affected under hypothetical scenarios of future water development. We conducted an analysis of historical rainfall data and future projections to consolidate data and discuss trends and the effects of ENSO on precipitation. Overall, results suggest that groundwater and surface water in Haʻikū are unlikely to be hydrologically connected due to statistically different geochemistry, which suggests that they originate from different source areas and elevations. However, in Huelo the opposite is found suggesting there may be different hydrogeologic or climatic factors that control groundwater-surface water interactions in different places. Groundwater model results indicate that the impact of future withdrawals can vary dramatically based on the geographic location of pumping wells and residential wells. These challenges all fall under the backdrop of decreasing rainfall trends between 1920 and present.
Drainage Failure and Associated Urban Impacts Under Combined Sea-Level Rise and Precipitation Scenarios
(University of Hawai'i at Manoa, 2024) Obara, Chloe; Fletcher, Charles H.; Earth and Planetary Sciences
Existing sea-level rise tools for coastal urban areas may overlook precipitation impacts on municipal infrastructure. In tidally-influenced coastal zones, high water levels can hinder stormwater systems, leading to drainage failure, corrosion, and backflow of contaminated water. Waikīkī, the tourism hub of Honolulu, faces growing risks of flooding and infrastructure damage due to rising sea levels. Using the PCSWMM modeling software, this study simulates drainage failure under present and projected sea levels combined with precipitation. Findings reveal that a 5-year precipitation event at present sea level floods more inlets than three feet of sea-level rise while a 10-year event floods three times more inlets than four feet of sea-level rise. By 2050, a 5-year event could cause flooding severe enough to disrupt transportation and contaminate stormwater inlets across 70% of Waikīkī. When accounting for precipitation, 100% of outfalls will fail and 85% of the drainage system will be full by 2040. Results indicate 22–50% more flooded inlets during precipitation events than passive models at present sea level. Salinity and water level data from storm drains show that coastal infrastructure faces severe corrosion risks, potentially worsening drainage failure. Findings support the need for adaptive stormwater management to address compounding flood risks.
The rapid emplacement of the 1823 CE Keaīwa lava flow from the Great Crack in the Southwest Rift Zone of Kīlauea volcano
(University of Hawai'i at Manoa, 2024) Tonato, Andrea; Shea, Thomas; Earth and Planetary Sciences
The 1823 CE Keaīwa lava flow in the Southwest Rift Zone (SWRZ) of Kīlauea volcano is uniquefor its expansive pāhoehoe sheet flow morphology and lack of constructive vent topography, despite having a similar tholeiitic basalt composition to other lavas erupted from Kīlauea. This lava flow issued from a ~10 km-long continuous fissure known as the Great Crack, and has an unusually thin sheet flow-like morphology with margin thicknesses of ~15–110 cm (average of 42 cm). Based on field observations of the lava flow at its fissure vent (e.g., drain-back features), we propose that the Great Crack formed, or at least significantly widened, syn-eruptively during the 1823 CE eruption. The absence of pyroclastic or scoria cones indicates that the eruption consisted of a rapid outpouring of relatively degassed lava as the fissure unzipped. This rapidly moving lava flow overtopped pre-existing tumuli and scoria cones (e.g., Lava Plastered Cones) up to ~10 m tall. Glass and whole-rock chemistry yield homogeneous compositions for the lavas erupted from the Great Crack, with glass compositions of 6.40 ± 0.10 wt. % and whole-rock compositions of 7.39 ± 0.07 wt. % MgO. A shorter western fissure system is richer in mafic minerals (e.g., olivine and clinopyroxene), and therefore the lavas from this fissure are slightly more MgO-rich (7.79 ± 0.05 wt. %). MgO-in-glass thermometry was used to calculate eruption temperatures of 1153± 13°C from spatter from the Great Crack fissure. These temperatures are typical of Kīlauea lavas, thus the extensive sheet-like lava flow morphology is not a direct consequence of unusual magmatic or rheological conditions (i.e. low viscosity). Instead the flow morphology is associated with high effusion rates caused by sudden drainage of uprift magma through the Great Crack. Lava flow modeling using VolcFlow on a 2 m DEM indicates that a minimum bulk effusion rate of ~11,200 m3/s (~6,700 m3/s dense rock equivalent, assuming ~40 % vesicularity) and a minimum flow velocity of ~11 m/s are required for the lava to overcome the Lava Plastered Cones. These effusion rates are amongst the highest inferred for eruptions in Hawai’i. This study sheds light on an anomalous eruption style that occurred from the unique fissure that is the Great Crack and the dynamics involved in its lava flow emplacement; providing new insights into potential risks and hazards during basaltic eruptions from Kīlauea and possibly Mauna Loa. An eruption similar to 1823 CE with a time frame shorter than an hour, high effusion rates, and rapid flow front velocities would not easily allow for evacuation.
Rate of Beach Loss Greatest with Near-term Sea Level Rise
(University of Hawai'i at Manoa, 2020) Tavares, Kammie; Fletcher, Chip; Earth and Planetary Sciences
Shoreline hardening threatens beaches globally and is a problem that is expected to accelerate with sea level rise (SLR). Modeling risk of hardening for future beaches provides important data for resource managers, communities, and other stakeholders. However, few comprehensive studies of this issue exist. For all sandy beaches on Oʻahu, Hawaiʻi, we model modern (2015) and future (0.25, 0.46, 0.74 m of SLR) erosion hazard zones. We identify the relationships between coastal land use patterns and erosion hazard zones to define areas at risk of hardening. Our results show half of the beachfront shoreline will be at risk of hardening at 0.74 m of SLR. Shorelines become increasingly at risk of hardening throughout all SLR scenarios, with the largest increase (+7.4% island-wide) occurring between modern-day and 0.25 m of SLR. Modern-day and near-term hardening under 0.25 m of SLR pose maximum risk of beach loss because of heavy development on some shoreline segments. Coastal communities in other settings may be facing significant modern-day and near-term threats to beach resources that have not been identified. Adaptation to SLR should be considered an immediate need and not solely a future issue.
Receiver Function Imaging of Kīlauea Using Broadband and Nodal Seismometers
(University of Hawai'i at Manoa, 2023) Wight, Jade Carrillo; Janiszewski, Helen; Earth and Planetary Sciences
Constraining the locations of magma storage at volcanoes helps improve our understanding of eruption processes and interpretations of volcano seismicity. A recent surge in deep seismicity beneath the Pāhala region on the Island of Hawai‘i prompted the 2022 deployment of nodal seismometers to seismically image the Southwest Rift Zone of Kīlauea. Using data recorded during 2022 and 2018 nodal deployments on Kīlauea, as well as data recorded from 2010 - 2022 by the nearby permanent broadband network maintained by the Hawaiian Volcano Observatory, we calculate teleseismic receiver functions, a traditional seismic imaging technique sensitive to abrupt changes in velocity, to image the crustal structure of Kīlauea. The use of nodal seismometers for passive seismic imaging targets has significantly expanded over the past decade, even though they are primarily sensitive to a higher frequency range than broadband seismometers. We utilize the broadband data to ensure reliability of the nodal data and expand our imaging scope across the Island of Hawai‘i. Using forward modeling techniques to analyze the receiver functions, we identify the potential presence of magma sills at the Southwest Rift Zone. Future work should include analysis of complementary datasets, and more sophisticated modeling techniques to rule out other potential structures.
Evaluation of microcontaminants as tracers for groundwater nutrient sources within mixed-use watersheds along the South Kohala coast of the Island of Hawaii
(University of Hawaii at Manoa, 2022) McKenzie, Casey D.; Dulai, Henrietta; Earth and Planetary Sciences
Anthropogenic nutrient loading of coastal environments is a known contributor to marine ecosystem health decline in Hawai‘i, and submarine groundwater discharge (SGD) has been shown to serve as a pathway to fuel nutrient delivery to coastal zones. Anthropogenic sources that may supply nitrogen (N) to groundwater include agricultural practices, resorts and golf courses that utilize fertilizers in landscaping applications, an abundance of homes outfitted with cesspools, and input from wastewater infrastructure. SGD provides a means of conveying land-derived nutrients to the coastal ocean and hence facilitates N-transport to coastal zones. Analysis of SGD enabled the exploration of the spatial distribution of groundwater composition and its relation to land-use. Previous research identified the presence of SGD in the study area, and we targeted and sampled 45 coastal springs and 20 upland wells along a 14 km long coastline in South Kohala, Hawai‘i. A wide range in nutrient concentrations was observed in SGD and well samples, with N loads well above 100 μM (1000-fold above marine levels). Some, but not all, δ15N-NO3- signatures suggest that N observed in SGD is of wastewater origin. We utilized known microcontaminants as novel tracers for identifying which land-use categories are hydrologically and chemically connected to SGD and, therefore, may be nutrient sources to the coastline. Microcontaminants of interest included pharmaceuticals commonly present in cesspool waste, restricted use pesticides and herbicides utilized in landscaping practices, and common detergents used in commercial industry that utilize public sewage infrastructure. To determine groundwater flow paths, δ18O-H2O allowed calculation of estimated recharge elevations to estimate upstream end members of flow lines. Spatial analysis of land uses and practices (LUP) along flow lines was utilized to quantify LUP overlying groundwater flow. δ18O-H2O of groundwater also contributed evidence of where groundwater flow paths from Kohala, Mauna Kea and Mauna Loa volcanoes may potentially converge along the South Kohala coastline. When comparing flow path analysis to developed scoring methods, upstream contribution of microcontaminants to groundwater pathways confirmed that microcontaminants could serve as land-use tracers throughout the length of the flow path. Microcontaminant scoring geochemically connected up-stream land uses to coastal SGD seeps along hydrological flow paths. Spatial analysis of microcontaminant distribution in SGD and LUP scoring revealed that caffeine, carbamazepine, sulfamethoxazole has strong correlation with presence of OSDS, confirming their suitability as wastewater specific tracers.
Revisiting the Census and Age of the Beta Pictoris Moving Group in the Gaia Era
(University of Hawaii at Manoa, 2022) Lee, Rena Aerey; Gaidos, Eric; Earth and Planetary Sciences
Determining the precise ages of young (~10 to few hundred Myr) kinematic ("moving") groups is important for placing star, protoplanetary disk, and planet observations on an evolutionary timeline. The nearby ~25 Myr-old Beta Pictoris Moving Group (BPMG) is an important benchmark for studying stars and planetary systems at the end of the primordial disk phase. Gaia DR3 astrometry combined with ground-based observations and more sophisticated stellar models permit a systematic re-evaluation of its membership and age. We combined Gaia astrometry with previous and new radial velocities to evaluate moving-group membership in a Bayesian framework. To minimize the effect of unresolved stellar multiplicity on age estimates, we identified and excluded multi-star systems using Gaia astrometry, ground-based adaptive optics imaging, and multi-epoch radial velocities, as well as the literature identifications. We estimated age using isochrone and lithium-depletion-boundary fitting with models that account for the effect of magnetic activity and spots on young, rapidly rotating stars. We report an age of 33(+9/-11) Myr to the BPMG based on isochrone fitting to the single-star and resolved-binary sample, which is older than, but within the uncertainties of, literature values.
Mantle vs. Crust: Untangling influences on ocean island basalt stable O and H isotopic composition via tandem olivine-glass analyses at Kamaʻehuakanaloa Volcano, Hawaiʻi
(University of Hawaii at Manoa, 2022) Cunningham, Molly Jean; Pietruszka, Aaron J.; Earth and Planetary Sciences
The stable O and H isotopic composition of ocean island basalts reflect the interplay of deep and shallow magmatic processes such as melting of a heterogeneous mantle source and crustal contamination. For Hawaiian volcanoes, it has been debated whether lavas retain their source-derived isotopic compositions, or if these signatures are overprinted by assimilation of hydrothermally altered materials. New δD and δ18O analyses of glass and olivine from the youngest Hawaiian volcano, Kamaʻehuakanaloa (Kamaʻehu; formerly Lōʻihi), clarify the extent to which magmatic contamination influences O and H isotope ratios of erupted lavas. We find that in most samples, assimilation of seawater-derived fluids is minor: this process has elevated δD, Cl/K2O, and H2O in some glasses, but most samples retain mantle-like δD (-60 to -90‰) until eruption. In contrast, Kamaʻehu lavas demonstrate variation in olivine δ18O (δ18Ool = ~4.5 to 5.4‰) and glass δ18O (δ18Ogl = ~5.0 to 6.2‰) that is greater than that expected from melting of simple peridotitic mantle. We find that different regions of the volcanic edifice erupt lavas that are compositionally distinct in their δ18O: North Rift Zone lavas are relatively 18O-enriched (δ18Ogl = ~5.6‰); South Rift Zone lavas are relatively 18O-depleted (δ18Ogl = ~5.3‰); and lavas from the summit region have intermediate δ18O values (δ18Ogl = ~5.4‰). We resolve these observations into an isotopically consistent model of the Kamaʻehu magmatic plumbing system. Over time, differences in the temperature of circulating hydrothermal fluids may have altered basalt in the volcanic edifice to high δ18O in the NRZ and low δ18O in the SRZ. Magmas with initial mantle-derived δ18O (δ18Oliq = ~5.4‰) ascend into the shallow volcanic plumbing system and assimilate this hydrothermally altered rock, causing individual magmas to shift toward the δ18O value of local assimilants. The degree of this contamination may be greatest in the rift zones and least in the summit due to a higher rate of magma supply to the summit reservoir system. δ18Ool tracks with regional differences in δ18Ogl, indicating that the assimilation process begins before or during olivine fractionation. Finally, olivine entrainment and lack of homogenization prior to eruption preserve isotopic heterogeneity on small spatial scales in erupted lavas. Variations in δ18O for Hawaiian lavas thus may be controlled by processes operating within the shallow volcanic plumbing system, overprinting variation derived from melting of a heterogeneous mantle source. To determine the true, mantle-derived O isotopic signature of a volcano, systematic analyses of many samples are required.
Assembling Primitive Cells Under Martian Geochemical Conditions: Implications for the Origin and Survivability of Life on Early Mars
(University of Hawaii at Manoa, 2022) Cary, Francesca Catherine Amy; Fagents, Sarah; Earth and Planetary Sciences
Mars has been a focus for decades of investigation, as a place in the solar system that could have been habitable for life as we know it. Despite being habitable early in its history, it is important to consider whether Mars could have originated life; a necessary foundation for understanding whether life could have inhabited Mars. Little work has been done to directly apply current knowledge about the origin of life to the unique conditions and planetary history of Mars. This research aims to take into account broad geochemical differences between Mars and Earth, such as Mars’ iron-rich surface, and assess how conducive early Mars was to originating life. Iron, calcium, and magnesium cations are abundant in hydrothermal settings on both Earth and Mars, which constitute promising environments for life’s origin. The impacts of different ionic compositions on the assembly, stability, and destruction of primitive cells have been investigated for this thesis. Additionally, we investigate other components in ancient hydrothermal settings that could have increased the stability and survivability of primitive cells. We find that iron destabilizes primitive cell membrane formation less than does calcium. The concentrations of cations required to completely destabilize primitive membranes are higher than those found in natural settings on Earth, but could potentially have reached these high concentrations on Mars as a consequence of the loss of surface water. In addition, dehydration-rehydration cycles of primitive membranes in the presence of RNA stabilize them against cations in solution. High concentrations of cations in solution thus could have functioned as a significant selective barrier on Mars. Interaction of membrane vesicles and functional polymers, which stabilize primitive cells against changes in the environment, could have been a mitigating factor. This work initiates an avenue of Mars astrobiology research that considers how cellular life may have evolved under the distinct planetary conditions and selective factors on Mars.
Groundwater Pollution From Onsite Disposal Systems And Other Land Uses On The ‘Ewa Plain, O‘ahu
(University of Hawaii at Manoa, 2022) Cameron, Jonathan; Glenn, Craig R.; Earth and Planetary Sciences
Due to historical and current agricultural practices, the use of recycled wastewater, and high-density on-site disposal systems (OSDS), the ‘Ewa Plain is at risk for harmful impacts related to excess nutrients entering its groundwater and coastal environments. Groundwater pollution on the flat, low gradient ‘Ewa Plain can transport nutrient pollution from source to ocean on short timescales. Identifying the type and concentrations of nutrients present in groundwater is important in understanding the overall impact that these nutrient fluxes have on groundwaters and coastal ecosystem health. Being comprised of thick layers of limestone covering most of the region’s surficial and subsurface geology, the ‘Ewa Plain is a unique geologic setting in Hawaii, and shallow groundwater flow within its flat, low gradient limestone wedge can transport nutrient pollution from source to the ocean on short timescales. This study combines several different approaches to locate and identify relative contributions of groundwater pollution within these sedimentary rocks, including electrical resistivity tomography (ERT), coastal salinity surveys, and geochemical tracers to identify sources of excess nutrients. A numerical groundwater model was created within the MT3DMS modeling environment to incorporate these results and simulates the relative impacts of total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN) pollution within this region. Results from near shore in situ ERT transects and lab tests of sediments indicate a layer of unconsolidated and consolidated beach sediments sitting atop a deeper limestone unit completely saturated with water, but failed to locate karstic conduits at either of the locations. Two along shore salinity surveys conducted located several zones of salinity below 35, and all but 19 measured salinity points were below 31. Submarine groundwater discharge along the shore appears to be mainly saline and diffuse, and may be emanating further offshore. Measured beachface pore water samples and groundwater well samples showed elevated nutrient values compared to standard ocean water. The numerical groundwater model environment MT3DMS was used to simulate the relative impact of total dissolved nitrogen and dissolved inorganic nitrogen from five different sources: background soil processes, OSDS, agriculture, golf courses, and recycled wastewater irrigation (R-1 water). The estimated impact from the MT3DMS model of total dissolved nitrogen and dissolved inorganic nitrogen into the ‘Ewa Plain indicate that the sources of highest relative anthropogenic nitrogen loading to groundwaters are widespread R-1 irrigation and more localized high-density OSDS related effluent.
Temporal Refinement of Water Budgets in Small Pacific Island Drainage Basins from Daily Rainfall and Temperature Maps
(University of Hawaii at Manoa, 2021) Brennis, Theodore; Lautze, Nicole C.; Earth and Planetary Sciences
Understanding the movement, distribution, and replenishment of groundwater is critical to sustainably managing this vital resource in Hawai‘i, USA, where groundwater meets more than 90% of freshwater needs statewide. Geochemical methods have been used increasingly to understand and model groundwater flow, but these methods are limited by the resolution of recharge measurements and the availability of precipitation chemistry data. Recent increases in climate data availability in Hawaiʻi allow water budgets to be examined with greater spatio-temporal resolution than ever before. While the current estimates of groundwater recharge are limited to annual long-term averages provided by the USGS, this paper provides a method for producing island-wide, monthly estimates of groundwater recharge using daily precipitation and temperature raster data. Recharge is calculated using a simple water budget: recharge ≈ precipitation – evapotranspiration – quickflow. Monthly precipitation, quickflow, evapotranspiration, and recharge are estimated for the island of Oʻahu between 1990 and 2014. Precipitation data are aggregated from recently published daily rainfall maps. Quickflow is calculated using simple regional regressions created by the USGS and compared with estimates from two different stream hydrograph baseflow separations. Evapotranspiration is calculated using a modification of the Thornthwaite equation, which was validated with local weather station data. The resulting estimates are compared with standards to quantitatively assess uncertainty and agreement. Our results show strong agreement with long-term average recharge estimates given by the USGS, and interannual climate trends further corroborate this agreement. These findings indicate that monthly estimates of groundwater recharge may be produced on Oʻahu via a low data intensity method with sufficient accuracy to better constrain recharge patterns for the island, and potentially improve groundwater management. These findings further suggest that the model presented here can be applied in any area where data on monthly precipitation, monthly temperature, and general quickflow trends are available.
Probabilistic Sea Level Rise Flood Projections Using a Localized Ocean Reference Surface
(University of Hawaii at Manoa, 2021) Paoa Kannegiesser, Noah Atariki; Fletcher, Charles H; Earth and Planetary Sciences
Projecting sea level rise (SLR) impacts requires defining ocean surface variability as asource of uncertainty. But tidal gauge data for this purpose are sparse. We analyze data from a Regional Ocean Modelling System (ROMS) reanalysis for the region surrounding the main Hawaiian Islands to incorporate the uncertainty of the ocean surface in mapping SLR flood probabilities. To validate the use of the ROMS reanalysis data we scanned it for daily highest high water using a 24-hour window and scanned the Honolulu tidal station data over the same time period (2007-2017) and at the same sampling interval (3hr). The mean higher high water (MHHW) value calculated with ROMS (0.296 ± 0.115 m) closely matches the MHHW calculated from the Honolulu tidal station data (0.304 ± 0.108 m above MSL). By analyzing the ocean surface height component of the ROMS reanalysis, we create an ocean surface reference (ORS) as a proxy for MHHW. We model the NOAA Intermediate, Intermediate-high and High regional SLR scenarios provided by Sweet et al. (2017) for the years 2050 and 2100 at three field sites around Oꞌahu; Waikīkī, Hauꞌula, Haleꞌiwa. We calculate a probability density function (PDF) by convolving the PDF of water level derived from the ROMS reanalysis data with the PDF of error associated with a digital elevation model of the study sites. The resulting joint-PDF of flood depth allows us to create two types of probability-based flood projections: (1) Maps illustrating varying flood depths for a given probability threshold and, (2) maps illustrating varying probability for a specific flood depth. We compare 80% probability flood projections using our ORS approach to projections using the TCARI grid, the standard NOAA method. We highlight the importance of uncertainty and user-defined probability in identifying pixels that function as tipping points distinguishing flooding styles.
Complex drivers of reef-fronted beach change
(University of Hawaii at Manoa, 2021) Mikkelsen, Anna Baker; Fletcher, Charles H; Earth and Planetary Sciences
Royal Hawaiian Beach in Waikīkī plays an essential role in Hawai‘i’s tourism-based economy. To inform development of management policies, we conduct two years of weekly ground and aerial surveys (April 2018 to February 2020) to track change on this chronically eroding beach. We use multiple linear regressions, Self-Organizing Maps (a form of cluster analysis), remotely sensed nearshore sand fields, hydrodynamic modelling, and monitoring of key physical processes to identify the principal drivers of beach change. Our results show 12 months of accretion (+2400 ± 59 m3) followed by 10 months of erosion (–3090 ± 51 m3) for a net loss of 690 ± 51 m3, and document that interannual variations in beach width and volume overprint seasonal patterns. Notably, a seasonal signal is recorded in the topographic structure of the beach. We test the relationship of beach volume and width to variations in wind, water level, and wave energy flux generated from southern hemisphere swell as well as locally generated trade-wind waves. We identify three beach segments and three nearshore sand fields that form a sand-sharing, source-sink network, yet operate quasi-independently. Our analysis reveals that individual beach segments and their adjacent sand fields experience coherent (simultaneous) gains and losses of sand, suggesting that alongshore sediment exchange is dominant over cross-shore exchange. The main drivers of beach change are variations in water level and wave energy flux. Beach volume and width both vary with nearshore sand cover, indicating that free exchange with nearshore sources is intrinsic to beach variability. Our results suggest that rising sea level and extreme El Niño-Southern Oscillation events will contribute to Royal Hawaiian Beach destabilization, which may amplify erosional events and increase the cost of future beach maintenance.
Analysis of Pacific Hotspot Chains and a Model for Recent Plume Drift
(University of Hawaii at Manoa, 2021) Chase, Andrew Arthur; Wessel, Paul; Earth and Planetary Sciences
Age-progressive seamount trails created by long-lived deep-mantle plumes have been used to establish absolute reference frames for plate motion. However, when plume drift is considered, changes in seamount trail direction and age progression rate cannot be attributed to plate motion change alone. A better understanding of these absolute motions are needed for studying the mantle dynamic processes that drive both plate tectonics and plume drift. For this study, improvements to age-progressive curves of eleven Pacific hotspot chains are made independently of past plate motion models. Our approach involves bathymetry processing to robustly predict a smooth and continuous hotspot path by connecting high points in seamount bathymetry, with uncertainties in the path based on seamount trail width and amplitude. Ages found using radiometric dating techniques from seamount samples are projected onto the inferred hotspot trail. A best-fit model of age as a function of along-track distance is determined, giving continuous age progressions for each seamount chain with uncertainties in both age and path. Three different types of paleolatitudes are also examined by incorporating data from the magnetization of seamount drill core samples, paleo-poles from marine magnetic anomaly skewness, and paleo-spin-axes from shifts in equatorial sediments. Improved paleolatitude curves for the Hawaiian-Emperor and Louisville chains are determined by combining these three different types of data. Paleolatitude curves are also determined for other chains where a sufficient amount of paleo-pole or paleo-spin-axis data are available. The data analysis of these eleven Pacific seamount chains provide prime constraints for future plate and plume motion models. For this study, we examine the data by accessing the change over time in distance between coeval seamounts, which infers relative drifts between the hotspots at different times in the past. We find that the inter-hotspot distance change since 6 Ma have been linear, given the (relatively large) errors, which prompted the development of a novel modeling approach. We end with inverting these linear relative rates via our new modeling scheme and solve for recent plume drifts for the time frame of 6 Ma to the present.
Magma-Assisted Flexure of Hawaiian Lithosphere Inferred From Three-Dimensional Models of Lithospheric Flexure and Active Source Seismic Data
(University of Hawaii at Manoa, 2021) Douglas, Daniel Leonard; Apuzen-Ito, Garrett; Earth and Planetary Sciences
We examine the deformation of the oceanic lithosphere beneath the Hawaiian Islands using 3D numerical models that simulate realistic rheologies including brittle failure, elasticity, low-temperature plasticity and high-temperature creep. Observations of flexure are provided by seismic imagery of the top of the pre-existing oceanic crust from legacy and novel active source seismic studies. When simulating normal lithospheric temperatures along with low-temperature flow laws that are weaker than inferred from rock physics experiments, the models successfully predict flexure near the older (2-4 Myr) volcanoes, confirming the results of prior studies. However, the models fail to predict flexure near the younger (<1 Myr) volcanoes. When simulating elevated temperatures due to hotspot magma that penetrated the lithosphere localized to beneath the island chain, models provide better fits to the observed flexure near both O‘ahu (2-4 Myr) and the Island of Hawai‘i (<1 Myr). These results argue against the need to revise published flow laws for low-temperature creep, supporting recent studies modeling lithospheric flexure at various Pacific subduction zones. Instead, the results indicate thermal and likely mechanical weakening localized beneath the island chain due to magma-assisted flexure.

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