Characterization And Interpretation Of Volcanic Activity At Redoubt, Bezymianny And Karymsky Volcanoes Through Direct And Remote Measurements Of Volcanic Emissions

Thesis (Ph.D.) University of Alaska Fairbanks, 2013Surface measurements of volcanic emissions can provide critical insight into subsurface processes at active volcanoes such as the influx or ascent of magma, changes in conduit permeability, and relative eruption size. In this dissertation I employ direct and remote measurements of volcanic emissions to characterize activity and elucidate subsurface processes at three active volcanoes around the North Pacific. The 2009 eruption of Redoubt Volcano, Alaska, produced elevated SO2 emissions that were detected by the Ozone Monitoring Instrument (OMI) satellite sensor for over three months. This provided a rare opportunity to characterize Redoubt's daily SO2 emissions and to validate the OMI measurements. Order of magnitude variations in daily SO2 mass were observed, with over half of the cumulative SO2 emissions released during the explosive phase of the eruption. Correlations among OMI daily SO2 mass, tephra mass and acoustic energies during the explosive phase suggest that OMI data may be used to infer eruption size and explosivity. From 2007 through 2010 direct and remote measurements of volcanic gas composition and flux were measured at Bezymianny Volcano, Kamchatka, Russia. During this period Bezymianny underwent five explosive eruptions. Estimates of passive and eruptive SO2 emissions suggest that the majority of SO2 is released passively. Order of magnitude variations in total volatile flux observed throughout the study period were attributed to changes in the depth of gas exsolution and separation from the melt at the time of sample collection. These findings suggest that exsolved gas composition may be used to detect magma ascent prior to eruption at Bezymianny Volcano. Karymsky Volcano, Kamchatka, Russia, is a dynamic volcano which exhibited four end-member activity types during field campaigns in 2011 and 2012, including: discrete ash explosions, pulsatory degassing, gas jetting, and explosive eruption. These activity types were characterized quantitatively and uniquely distinguished using a multiparameter dataset based on infrasound, thermal imagery, and volcanic emissions. These observations suggest a decoupling between exsolved volatiles and magma at depth. I propose that variations in magma degassing depth influence the flux and proportions of decompression- and crystallization-induced degassing, as well as conduit permeability, can explain the variations in volcanic activity

Estimates of volcanic mercury emissions from Redoubt Volcano, Augustine Volcano, and Mount Spurr eruption ash

Ash is a potential sink of volcanically sourced atmospheric mercury (Hg), and the concentration of particle-bound Hg may provide constraints on Hg emissions during eruptions. We analyze Hg concentrations in 227 bulk ash samples from the Mount Spurr (1992), Redoubt Volcano (2009), and Augustine Volcano (2006) volcanic eruptions to investigate large-scale spatial, temporal, and volcanic-source trends. We find no significant difference in Hg concentrations in bulk ash by distance or discrete eruptive events at each volcano, suggesting that in-plume reactions converting gaseous Hg0 to adsorbed Hg2+ are happening on shorter timescales than considered in this study (minutes) and any additional in-plume controls are not discernable within intra-volcanic sample variability. However, we do find a significant difference in Hg concentration of ash among volcanic sources, which indicates that volcanoes may emit comparatively high or low quantities of Hg. We combine our Hg findings with total mass estimates of ashfall deposits to calculate minimum, first-order Hg emissions of 8.23 t Hg for Mount Spurr (1992), 1.25 t Hg for Redoubt Volcano (2009), and 0.16 t Hg for Augustine Volcano (2006). In particular, we find that Mount Spurr is a high Hg emitting volcano, and that its 1992 particulate Hg emissions likely contributed substantially to the global eruptive volcanic Hg budget for that year. Based on our findings, previous approaches that use long-term Hg/SO2 mass ratios to estimate eruptive total Hg under-account for Hg emitted in explosive events, and global volcanogenic Total Hg estimates need revisiting

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Multidisciplinary Constraints on Magma Compressibility, the Pre‐Eruptive Exsolved Volatile Fraction, and the H2O/CO2 Molar Ratio for the 2006 Augustine Eruption, Alaska

Abstract Geodetically modeled reservoir volume changes during volcanic eruptions are commonly much smaller than the observed eruptive volumes. This discrepancy is thought to be partially due to the compressibility of magma, which is largely controlled by the presence of exsolved volatiles. The 2006 eruption of Augustine Volcano, Alaska, produced an eruptive volume that was ∼3 times larger than the geodetically estimated syn‐eruptive subsurface volume change. In this study, we use a multistep methodology that combines constraints from geodetic, volcanic gas, geologic, and petrologic data together with equations relating physical processes to observable parameters. We apply a Monte Carlo approach to quantify uncertainties. Ultimately, we solve for the exsolved volatile volume fraction and the magma compressibility. We estimate Augustine's 2006 pre‐eruptive exsolved volatile phase to be ∼5.5 vol% of the magma at storage depths, yielding a bulk magma compressibility of ∼3.8 × 10−10 Pa−1. We develop a novel approach to estimate the H2O/CO2 ratio of the syn‐eruptive gas emissions in the absence of direct H2O emission measurements which are hard to obtain due to the high background levels in ambient air. We find a best‐fit H2O/CO2 molar ratio of 29. We also investigate the effects of applying different equations of state to our model. We find that the Ideal Gas Law might be used as a first approximation due to its simplicity; however, it overestimates volatile density and compressibility significantly at storage depths. This project capitalizes on the insights that can be gained by integrating multidisciplinary data with models of physical processes

Combining Local and Remote Infrasound Recordings from the 2009 Redoubt Volcano Eruption

The explosive phase of the 2009 Redoubt Volcano eruption produced predominantly short duration, high-amplitude infrasound signals recorded up to 4500 km away. All 19 numbered explosive events were recorded at a local microphone (DFR, 12 km), as well as at an infrasound array in Fairbanks, Alaska (I53US, 547 km), most with high signal to noise ratios. The local microphone provides an estimate of the source parameters, and comparison between the two datasets allows the unique opportunity to evaluate acoustic source term estimation at a remote array. High waveform similarity between DFR and I53US occurs during much of the explosive phase due to strong stratospheric ducting, permitting accurate source constraints inferred from I53US data. Cross-correlation analysis after applying a Hilbert transform to the I53US data shows how the acoustic energy has passed through a single caustic, as predicted by ray theory. Similar to previous studies, significant low-frequency infrasound from Redoubt recorded at I53US is coincident with high-altitude ash emissions. The largest events also produced considerable energy at greater than 50 s periods, likely related to the initial oscillations of the volcanic plume or jet. Many of the explosive events have emergent onsets, somewhat unusual for explosive, short-duration eruptions. Comparison of the satellite-derived SO2 emissions with the relative amount of acoustic energy at I53US shows a very high, statistically significant correlation. This study reiterates the utility of using remote infrasound arrays for detection of hazardous emissions and characterization of large volcanic eruptions, and demonstrates how, under typical meteorological conditions, remote infrasound arrays can provide an accurate representation of the acoustic sourc

Gas Emissions From the Western Aleutians Volcanic Arc

The Aleutian Arc is remote and highly active volcanically. Its 4,000 km extent from mainland Alaska to Russia’s Kamchatka peninsula hosts over 140 volcanic centers of which about 50 have erupted in historic times. We present data of volcanic gas samples and gas emission measurements obtained during an expedition to the western-most segment of the arc in September 2015 in order to extend the sparse knowledge on volatile emissions from this remote but volcanically active region. Some of the volcanoes investigated here have not been sampled for gases before this writing. Our data show that all volcanoes host high-temperature magmatic-hydrothermal systems and have gas discharges typical of volcanoes in oceanic arcs. Based on helium isotopes, the western Aleutian Arc segment has minimal volatile contributions from the overriding crust. Volcanic CO2 fluxes from this arc segment are small, compared to the emissions from volcanoes on the Alaska Peninsula and mainland Alaska. The comparatively low CO2 emissions may be related to the lower sediment flux delivered to the trench in this part of the arc

Economic burden and secondary complications of influenza-related hospitalization among adults in the US: a retrospective cohort study

This study aims to describe the healthcare resource utilization (HCRU) and direct medical cost of influenza-related hospitalizations to illustrate the persistent economic burden of influenza among adults in the US. A retrospective cohort study was conducted using the PINC AI Healthcare Database. Adults hospitalized with a diagnosis of influenza between August 1–May 31 from 2016–2023 were identified and stratified by age (18–49, 50–64 and ≥65 years). The index hospitalization was defined as the individual’s first influenza-related hospitalization during each season. Patient demographics, comorbidities, and hospitalization characteristics were assessed during the index hospitalization. Index hospitalization length of stay (LOS), in-hospital mortality, intensive care unit (ICU) admissions, mechanical ventilation (MV) usage, and costs were evaluated overall and by MV usage, ICU admission, and secondary complication status. Pre-index influenza-related outpatient and emergency department (ED) visits (7 days prior) were also evaluated. Primarily initiated in the ED, the median LOS for influenza-related hospitalizations was 3–4 days. Inpatient mortality increased with age (2.2–4.4%). Combined mean hospitalization and initial ED visit costs were $12,556–$14,494 (2017/18; high severity season) and $11,384–$12,896 (2022/23; most recent season). Compared to other age groups, adults ≥65 years had higher proportions of hospitalization with no MV or ICU usage. Adults 18–49 years had the highest proportion of ICU admission only, whereas adults 50–64 years had the highest MV usage only and both MV and ICU admission. MV and/or ICU usage was associated with higher hospitalization costs. Increasing proportionally with age, the majority of influenza-related hospitalizations had a secondary complication diagnosis, which were associated with elevated costs. Analysis of this hospital-based administrative database relied on coding accuracy. Only hospital system-associated outpatient/ED visits were captured; the full scope of HCRU was under-ascertained. The economic burden of influenza-related hospitalizations remains substantial, driven by underlying conditions, MV/ICU usage and secondary complications. This study described the healthcare resource utilization (HCRU) and costs for US adults ≥18 years old hospitalized with influenza and associated secondary complications such as pneumonia, asthma exacerbation and malignant hypertension between 2016–2023. The researchers analyzed a hospital admission database and found that, for the healthcare system, average cost per influenza-related hospitalization ranged from $11,384 to$14,494, depending on the influenza season and age of the patient. Over 96% of patients admitted to a hospital initially presented at the emergency department, 20–30% of patients required mechanical ventilation (MV) or intensive care unit (ICU) admission, and the median hospital length of stay was 3–4 days. This study adds to the existing evidence by providing economic burden estimates for the 2022/23 influenza season, the most recent influenza season after the COVID-19 pandemic, and found slightly lower HCRU and cost for influenza hospitalizations relative to prior seasons. Also, the study comprehensively analyzed economic burden by patient age groups and found lower HCRU and costs among patients ≥65 years compared to adults 18–49 years and 50–64 years consistently for all seasons. Additionally, the study found that the proportion of patients with MV usage alone, with MV usage and an ICU admission, and average hospitalization costs were greatest among patients 50–64 years, highlighting the potential benefit of increasing rates of seasonal influenza vaccination among this age group. Finally, the study found higher costs among patients with complications related to their influenza infection compared to patients without complications. Overall, the study found that influenza-related hospitalization can contribute to substantial economic burden in the US in the most recent time period.</p