12. Unnsteinsson, T; Flowers, G; Williams-Jones, G.Formation and persistence of glaciovolcanic voids explored with analytical and numerical models.Journal of Glaciology, 2024, Formation and persistence of glaciovolcanic voids explored with analytical and numerical models
glacier, volcano, numerical model, Mt. Meager
One fifth of Earth’s volcanoes are covered by snow or ice and many have active geothermal systems that interact with the overlying ice. These glaciovolcanic interactions can melt voids into glaciers, and are subject to controls exerted by ice dynamics and geothermal heat output. Glaciovol11 canic voids have been observed to form prior to volcanic eruptions, which raised concerns when such features were discovered within Job Glacier on Qwelqwelústen (Mount Meager Volcanic Complex), British Columbia, Canada. In this study we model the formation, evolution, and steady-state morphol15 ogy of glaciovolcanic voids using analytical and numerical models. Analytical steady-state void geometries show cave height limited to one quarter of the ice thickness, while numerical model results suggest the void height h scales with ice thickness H and geothermal heat flux Q as h/H = aHbQc, with exponents b =-n/2 and c = 1/2 where n is the creep exponent. Applying this scaling to the glaciovolcanic voids within Job Glacier suggests the potential for total geothermal heat flux in excess of 10 MW. Our results show that relative changes in ice thickness are more influential in glaciovolcanic void formation and evolution than relative changes in geothermal heat flux. DOI
11. Anzieta, J, Pacheco, D, Williams-Jones, G, Ruiz, M.Cleaning volcano‑seismic event catalogues: a machine learning
application for robust systems and potential crises in volcano
observatories.Bulletin of Volcanology, 2023, 85: 59 Cleaning volcano‑seismic event catalogues: a machine learning
application for robust systems and potential crises in volcano
observatories
Volcano-seismic events, Volcano catalogues, Machine learning, Volcano observatories, Volcanic crises
Complete and precise volcano-seismic event catalogues are important not only for the statistical value that they possess for
describing past volcanic activity, but also because they constitute the input for automated systems that help monitor volcanic
activity in real time. Computer systems are valuable assets in the task of volcano-seismic event classification because in
theory they can have improved performance compared to humans due to speed, consistency, and unbiasedness. However, such
systems are trained with data from previously created catalogues of events, and as such, if catalogues have noise, the systems
will learn incorrectly. In this work, we propose the implementation of a methodology that is relatively easy and fast to apply
for the identification of potentially mislabeled events in a seismic event catalogue. We compare the results of applying the
procedure to two open catalogues from Cotopaxi and Llaima volcanoes. The first catalogue is believed to have an unknown
but potentially significant level of noise, while the other is assumed to be clean. We further validate our results for one of
the datasets with volcano observatory scientists in a blind-review fashion to demonstrate some of the hypotheses that can
arise in a catalogue with a presumably important level of noise. We conclude that the methodology is valid for identifying
potentially mislabeled seismic events and can help in assessing the quality of a given catalogue.PDF DOI
10. Le Moigne, Y; Vigouroux, N; Russell, JK; Williams-Jones, G.Magmatic origin and storage conditions for the eruption of Tseax volcano, Northern Cordillera Volcanic Province, Canada.Chemical Geology, 2022, 588: 120648 Magmatic origin and storage conditions for the eruption of Tseax volcano, Northern Cordillera Volcanic Province, Canada.
Monogenetic volcano, Tseax volcano, Northern Cordilleran Volcanic Province, Basanite, Plumbing system
The Northern Cordilleran Volcanic Province (NCVP) is the most active volcanic belt in Canada, yet there are few detailed petrologic studies of the individual volcanoes. Tseax volcano is the southernmost volcanic centre of the NCVP, the second youngest (~ 1700 CE) eruption in Canada, and is one of Canada’s worst natural disasters killing up to ~ 2,000 Nisga’a First Nation people. We present a conceptual model for the origins, evolution and pre-eruptive storage of the Tseax magma which erupted ~ 0.5 km3 of volcanic material, mainly in the form of valley-filling lava flows. All Tseax products are alkali Fe- Ti- rich basanite-to-tephrite having trace element distributions similar to the other mafic NCVP lavas. Phenocrysts consist of plagioclase, olivine and titanomagnetite, often forming glomerocrysts suggesting co-crystallisation of these 3 mineral phases. Clinopyroxene is never observed as a phenocryst phase. The lavas have low Mg#’s implying they are fractionated relative to a mantle-derived ‘parent’ magma. Trace elements indicate the magma derives from melting of a fertile mantle source (i.e., (Nb/K)n ~1), most likely the upper asthenosphere. There is no evidence in the Tseax volcanic rocks for magma mixing or lithospheric contamination during ascent. The phenocryst assemblage suggests rapid ascent of a low viscosity magma to < 5.5 km where titanomagnetite becomes the first phase on the liquidus (~ 1133 °C). There the magma stalled for a very short period of time under P-T conditions where clinopyroxene did not reach saturation. Based on the size of the plagioclase phenocrysts, the magma stalled for less than a year and cooled down to 1094 - 1087 °C prior to eruption.Website DOI
9. Le Moigne, Y; Williams-Jones, G; Vigouroux, N; Russell, JK.Chronology and eruption dynamics of the historic ~ 1700 CE eruption of Tseax Volcano, British Columbia, Canada.Frontiers in Earth Science, 2022, 10: 910451 Chronology and eruption dynamics of the historic ~ 1700 CE eruption of Tseax Volcano, British Columbia, Canada.
Tseax volcano; Monogenetic volcanism; Lava flow; Eruption dynamics; Indigenous knowledge
The eruption of Tseax volcano in ~1700 CE, in north-western British Columbia, is the second youngest volcanic event in Canada. It is also one of Canada’s worst natural disasters as it killed up to 2,000 people of the Nisga’a First Nation living there at the time. The eruption also significantly impacted the local environment by diverting the Nass River (the 3rd largest river in British Columbia). Within the Nisga’a culture, Adaawak stories preserve an observational account of the Tseax eruption. In this study, we establish the chronology of the eruption by integrating field observations, petrophysical data and Nisga’a oral and written histories. The Nisga’a stories corroborate the short duration and exceptional intensity of the eruption as recorded in the volcanic products. The eruption was divided in two main periods: (1) Period A and (2) Period B. (1) The eruption started in a typical Hawaiian style with low levels of lava fountaining that built up a spatter rampart. This pyroclastic edifice was breached by voluminous pāhoehoe lava flows erupted at high discharge rates. We estimate that almost half of the erupted flow volume (0.20 km3) erupted in Period A was emplaced at 800-1000 m3/s. The lava reached the Nass Valley, 20 km downstream of the volcano, in “swift currents”, diverted the Nass River and engulfed the former Nisga’a villages in only 1 to 3 days, thus likely being responsible for the reported fatalities. The discharge rates progressively diminished to 10-200 m3/s until the end of this first eruptive period, which lasted a few weeks to a few hundred days. (2) During Period B, two ‘a‘ā flows were erupted with discharge rates < 50 m3/s. This period was also characterised by a more explosive eruption style that built a 70 m high tephra cone overlapping with spatter rampart. In total, Period B lasted approximately 20 days. In total, the eruption produced 0.5 km3 of volcanic materials (mostly in the form of lava flows) on the order of weeks to a few months. The short duration of the eruption was probably inherent to the limited amount of melt produced in the mantle. However, the eruption of Tseax was similar in magnitude to the flank eruption on larger shield volcanoes such as Kīlauea’s Fissure 8 in 2018 or Mauna Loa in 1984.PDF DOI
8. Warwick, R; Williams-Jones, G; Kelman, M; Witter, JB.A scenario-based volcanic hazard assessment for the Mount Meager Volcanic Complex, British Columbia.Journal of Applied Volcanology, 2022, 11:1-22 A scenario-based volcanic hazard assessment for the Mount Meager Volcanic Complex, British Columbia.
Mount Meager; Hazard scenarios; Pyroclastic density currents; Lahars; Tephra fall
The Mount Meager Volcanic Complex (Mount Meager) is a glacier-clad stratovolcanic system in southwestern British Columbia which last erupted over 2400 years ago (VEI 4). While this is Canada’s most recent major explosive eruption, most past research on Mount Meager has focused on its numerous and large volume landslides and thus the volcanic hazard characteristics remain understudied. Here we present a suite of scenario-based hazard maps and an assessment addressing a range of potential future explosive eruptions and associated hazards. In order to overcome limited knowledge of the eruptive history, numerical models have been used to simulate the primary syneruptive hazards of concern (dome-collapse pyroclastic density currents, lahars and tephra fallout) largely utilizing eruption parameters from analogous volcanoes, i.e., glacier-clad stratovolcanoes in a subduction zone setting. This study provides a framework for similar volcanic hazard studies where geologic data is limited, funds are minimal, and access is difficult. Furthermore, this sets the stage for recognizing volcanic hazards in the Canadian landscape, providing a resource to prepare for and mitigate potential impacts well in advance of a crisis situation. Website DOI
7. Le Moigne, Y, Zurek, JM, Williams-Jones, G, Lev, E; Calahorrano-Di Patre, A; Anzieta, JC.Standing waves in high speed lava channels: A tool for constraining lava flow dynamics and eruptive parameters.Journal of Volcanology and Geothermal Research, 2020, 401, 106944 Standing waves in high speed lava channels: A tool for constraining lava flow dynamics and eruptive parameters
Standing waves; Hydraulic jumps; Supercritical flow; Lava viscosity; Lava flow; Basalt; Real time monitoring
Estimates of the rheological properties of lava flows are essential for understanding their emplacement and for hazard assessment. Despite being a well-known phenomenon in water hydraulics, the formation and presence of standing waves in lava channels is poorly understood. Standing waves, generally located near the vent area, have been frequently described at high speed channelized lava flows. They are interpreted as hydraulic jumps indicating a flow under supercritical conditions. Identifying standing waves therefore offers an opportunity to apply open channel hydraulic theory for supercritical flows in order to determine important eruption parameters such as discharge rate and apparent viscosity. We use the length and amplitude of standing waves to reconstruct flow dynamics from both observational data and video analysis. The geometry of these standing waves allows us to extract the physical properties of the channelized lava (velocity, discharge rate, apparent viscosity), to estimate the channel depth and constrain the flow regime. With the rapid advances in technology, scientists can deploy equipment to enable low-cost real time monitoring of these phenomena and constrain eruption discharge rate and apparent viscosity, key parameters for volcanic hazard assessment and mitigation.PDF DOI
6. Le Moigne, Y; Williams-Jones, G; Russell, JK; Quane, S.Physical volcanology of Tseax volcano, British Columbia, Canada.Journal of Maps, 2020, 16(2), 363-375 Physical volcanology of Tseax volcano, British Columbia, Canada
Tseax volcano; lava flow; mapping; DEM; bathymetry
Tseax volcano erupted ∼ 250 years ago in NW British Columbia, Canada producing tephra deposits and lava flows. Field mapping has defined the stratigraphy of Tseax and the lava flow morphologies. Aerial photogrammetry and bathymetry surveys were used to create a high resolution digital elevation model of the volcano to facilitate mapping and estimates of erupted material volumes. Tseax volcano (∼ 10.4 ± 0.7 × 106 m3) comprises an outer
breached spatter rampart and an inner conical tephra cone. Tseax is associated with a 32 km long and 0.49 ± 0.08 km3 basanite-to-tephrite lava flow field covering ∼ 36 km2 and divided into 4 distinct lava flows with heterogeneous surface morphologies. We present a volcanological map of Tseax volcano at a scale of 1:22,500. This will serve as supporting information for further research on the eruptive history of Tseax volcano and the lava flow field emplacement.PDF DOI
5. Venugopal, S; Schiavi, F; Moune, S; Bolfan-Casanova, N; Druitt, T; Williams-Jones, G.Melt inclusion vapour bubbles: the hidden reservoir for major, trace and volatile elements.Nature Scientific Reports, 2020, 10, 9034 Melt inclusion vapour bubbles: the hidden reservoir for major, trace and volatile elements.
Olivine-hosted melt inclusions (MIs) provide samples of magmatic liquids and their dissolved volatiles from deep within the plumbing system. Inevitable post-entrapment modifcations can lead to signifcant compositional changes in the glass and/or any contained bubbles. Re-heating is a common technique to reverse MI crystallisation; however, its efect on volatile contents has been assumed to be minor. We test this assumption using crystallised and glassy basaltic MIs, combined with Raman spectroscopy and 3D imaging, to investigate the changes in fuid and solid phases in the bubbles before and after re-heating. Before re-heating, the bubble contains CO2 gas and anhydrite (CaSO4) crystallites. The rapid difusion of major and volatile elements from the melt during re-heating creates new phases within the bubble: SO2, gypsum, Fe-sulphides. Vapour bubbles hosted in naturally glassy MIs similarly contain a plethora of solid phases (carbonates, sulphates, and sulphides) that account for up to 84% of the total MI sulphur, 80% of CO2, and 14% of FeO. In both re-heated and naturally glassy MIs, bubbles sequester major and volatile elements that are components of the total magmatic budget and represent a “loss” from the glass. Analyses of the glass alone signifcantly underestimates the original magma composition and storage parameters.PDF DOI
4.Williams-Jones, G; Barendregt, RW; Russell, JK; Le Moigne, Y; Enkin, RJ; Gallo R.The age of the Tseax volcanic eruption, British Columbia, Canada.Canadian Journal of Earth Sciences, 2020, The age of the Tseax volcanic eruption, British Columbia, Canada
Tseax volcano; lava flow; tephra cone; paleomagnetism; radiocarbon dating; geochemistry
A recent volcanic eruption occurred at Tseax volcano that formed a series of tephra cones in northwestern British Columbia, Canada. The explosive to effusive eruption also formed a 32 km sequence of Fe-rich Mg-poor basanite–trachybasalt lavas covering 40 km2. Oral stories of the Nisg_a’a Nation report that the eruption may have caused as many as 2000 fatalities. The actual eruption date and question of whether there was one or multiple eruptive episodes in the 14th and 18th centuries are, as of yet, unresolved. New radiocarbon dating of wood charcoal from immediately beneath vent-proximal tephra deposits and complementary age information suggest an eruption in 1675–1778 CE (95.4% probability) was responsible for the formation of the tephra cone. New paleomagnetic and geochemical data from the tephra cone and lava flows suggest there is, in fact, no statistically significant difference in time between the explosive and effusive deposits and that they formed during a single eruptive episode.PDF DOI
3. Venugopal, S; Moune, S; Williams-Jones, G; Druitt, T; Vigouroux, N; Wilson, A; Russell, JK.Two distinct mantle sources beneath the Garibaldi Volcanic Belt: Insight from olivine-hosted melt inclusions.Chem. Geol., 2019, 532, 119346 Two distinct mantle sources beneath the Garibaldi Volcanic Belt: Insight from olivine-hosted melt inclusions
Melt inclusions; Garibaldi Volcanic Belt; Cascades; Trace elements; Two mantle sources
The nature of the magmatic source beneath the Garibaldi Volcanic Belt (GVB) in NW Washington (USA) and SW British Columbia (Canada) has been debated both due to its classification as the northern equivalent of the High Cascades and the alkaline nature of northern basalts. Whole rock studies have shown that the GVB does not share the same magmatic source as the High Cascades (Mullen and Weis, 2013, 2015). Nonetheless, the presence of alkaline basalts in this arc raises questions about the exact source of mantle enrichment and whether it is related to the young age of the downgoing Juan de Fuca Plate ( < 10 Ma) or the presence of a slab tear at the northern end of the arc. To gain insight into the source that underlies the GVB, we sampled olivine-hosted melt inclusions from each volcanic centre along the arc. Major, volatile and trace element data reveal a northward compositional trend from arc-typical calc-alkaline magma in the south to OIB-like melts in the north near the slab tear. Furthermore, contributions from the subducting slab are relatively high beneath the southern end of the arc (Cl/Nb > 80) but rapidly decreases to the north (Cl/Nb < 50). Finally, the significant differences in Zr/Nb from south to north (80 and 9, respectively) suggest two distinct mantle sources since one source cannot produce melts with such different ratios. As such, we propose the GVB should be segmented into the Northern and Southern groups, each having its own mantle source. Based on the geographic proximity, the enriched nature of the Northern group melt inclusions is likely controlled by the slab tear at the northern termination of the subducting Juan de Fuca Plate. Melt modelling results show that 3-7 % partial melting of the primitive mantle with a garnet lherzolite residue can reproduce the composition of the Northern group. Melt inclusions from the Southern group, on the other hand, imply a depleted MORB mantle that has been modified by fluids derived from the downgoing slab. Variability within the Southern group itself reflects the amount of hydrous fluids supplied beneath each centre and is correlated with slab age and subsequent degree of dehydration. This study addresses the compositional diversity along the arc and provides evidence that the age of the downgoing plate and the presence of a slab tear exert a strong compositional control over eruptive products within one arc.PDF DOI
2. MacQueen, P; Zurek, J; Williams-Jones, G.Connected magma plumbing system between Cerro Negro and El Hoyo Complex, Nicaragua revealed by gravity survey.Journal of Volcanology and Geothermal Research, 2016, 327: 375-384 Connected magma plumbing system between Cerro Negro and El Hoyo Complex, Nicaragua revealed by gravity survey
Gravity; Nicaragua; Cerro Negro; El Hoyo; Structure; Magmatic plumbing
Cerro Negro, near Leon, Nicaragua is a young, relatively small basaltic cinder cone volcano that has been unusually active during its short lifespan. Multiple explosive eruptions have deposited significant amounts of ash on Leon and the surrounding rural communities. While a number of studies investigate the geo-chemistry and stress regime of the volcano, subsurface structures have only been studied by diffuse soil gas surveys. These studies have raised several questions as to the proper classification of Cerro Negro and its relation to neighboring volcanic features. To address these questions, we collected 119 gravity measurements around Cerro Negro volcano in an attempt to delineate deep structures at the volcano. The resulting complete Bouguer anomaly map revealed local positive gravity anomalies (wavelength 0.5 to 2 km, magnitude +4 mGal) and regional positive (10 km wavelength, magnitudes +10 and +8 mGal) and negative (12 and 6 km wavelength, magnitudes 18 and 13 mGal) Bouguer anomalies. Further analysis of these gravity data through inversion has revealed both local and regional density anomalies that we interpret as intrusive complexes at Cerro Negro and in the Nicaraguan Volcanic Arc. The local density anomalies at Cerro Negro have a density of 2700 kg m(-3) (basalt) and are located between -250 and -2000 m above sea level. The distribution of recovered density anomalies suggests that eruptions at Cerro Negro may be tapping an interconnected magma plumbing system beneath El Hoyo, Cerro La Mula, and Cerro Negro, and more than seven other proximal volcanic features, implying that Cerro Negro should be considered the newest cone of a Cerro Negro-El Hoyo volcanic complex. (C) 2016 Elsevier B.V. All rights reserved.PDF DOI
1. Miller, CA; Williams-Jones, G.Internal structure and volcanic hazard potential of Mt Tongariro, New Zealand, from 3D gravity and magnetic models.Journal of Volcanology and Geothermal Research, 2016, 319: 12-28 Internal structure and volcanic hazard potential of Mt Tongariro, New Zealand, from 3D gravity and magnetic models
Gravity; Magnetic; 3D modelling; Volcanic hazard; Hydrothermal system; Volcanic structure
A new 3D geophysical model of the Mt Tongariro Volcanic Massif (TgVM), New Zealand, provides a high resolution view of the volcano's internal structure and hydrothermal system, from which we derive implications for volcanic hazards. Geologically constrained 3D inversions of potential field data provides a greater level of insight into the volcanic structure than is possible from unconstrained models. A complex region of gravity highs and lows (+/- 6 mGal) is set within a broader, similar to 20 mGal gravity low. A magnetic high (1300 nT) is associated with Mt Ngauruhoe, while a substantial, thick, demagnetised area occurs to the north, coincident with a gravity low and interpreted as representing the hydrothermal system. The hydrothermal system is constrained to the west by major faults, interpreted as an impermeable barrier to fluid migration and extends to basement depth. These faults are considered low probability areas for future eruption sites, as there is little to indicate they have acted as magmatic pathways. Where the hydrothermal system coincides with steep topographic slopes, an increased likelihood of landslides is present and the newly delineated hydrothermal system maps the area most likely to have phreatic eruptions. Such eruptions, while small on a global scale, are important hazards at the TgVM as it is a popular hiking area with hundreds of visitors per day in close proximity to eruption sites. The model shows that the volume of volcanic material erupted over the lifespan of the TgVM is five to six times greater than previous estimates, suggesting a higher rate of magma supply, in line with global rates of andesite production. We suggest that our model of physical property distribution can be used to provide constraints for other models of dynamic geophysical processes occurring at the TgVM. (C) 2016 Elsevier B.V. All rights reserved. DOI
