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Understanding maar-forming eruptions: An integrative approach to link surface deposits and eruption dynamics to shallow volcanic processes

Applicant Lefebvre Nathalie
Number 158302
Funding scheme Marie Heim-Voegtlin grants
Research institution Institut für Geochemie und Petrologie ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geology
Start/End 01.10.2015 - 30.09.2017
Approved amount 222'372.00
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All Disciplines (3)

Discipline
Geology
Other disciplines of Earth Sciences
Geochemistry

Keywords (10)

phreatomagmatic; melt inclusions; textural analysis; basaltic; maar-diatreme volcano; volcanism; fragmentation; juvenile pyroclast; scoria; morphological studies

Lay Summary (German)

Lead
Maar-Diatrem-Vulkane sind die zweithäufigsten Vulkantypen auf Kontinenten und die explosivste Art von kleinvolumigen Vulkanen. Solche Eruptionen dauern typischerweise mehrere Tage bis einige wenige Jahre, wobei erneute Eruptionen in der Regel nicht an den gleichen Orten ausbrechen. Verglichen mit bekannteren Vulkantypen mit positivem topographischem Relief sind sie einzigartig, da sich der grösste Teil ihrer Struktur annäherungsweise trichterförmig unter der Erdoberfläche befindet. Mehrere dicht besiedelte Städte wie z.B. Auckland, Mexico City oder Managua wurden auf aktiven vulkanischen Feldern mit Maar-Vulkanen gebaut. Diese hochexplosiven Eruptionen haben ein hohes Schadenspotential, welches mit der Zerstörung von Leben, Vegetation und Infrastruktur ein riesiges sozioökonomisches Ausmass annehmen kann. Jedoch sind die Faktoren, welche Maar bildende Eruptionen auslösen und welche für die Gefahrenabschätzung von zentraler Wichtigkeit sind noch immer weitgehend unbekannt.
Lay summary

 Inhalt und Ziel des Forschungsprojekts 

Das Hauptziel dieses Projektes ist es, die Schlüsselfaktoren für Maar-Eruptionen besser verstehen und abschätzen zu können. Dazu werden wir vulkanische Ablagerungen der Ukenrik Eruption von 1977 in Alaska - der jüngsten und bestdokumentierten Maar-Eruption - im Lichte neuster geochemischer und texturanalytischer Methoden untersuchen. Unser Augenmerk liegt dabei bei der Bestimmung: 1. des Ablaufs des Magmaaufstiegs; 2. des Gasbudgets und den Typen von involvierten Gasen; und 3. den physischen Charakteristiken des Magmas bei der Eruption nahe der Oberfläche.

Wissenschaftlicher und gesellschaftlicher Kontext des Forschungspro-jekts 

Im Zusammenhang mit früheren Beobachtungen der Eruption selbst sowie mit detaillierten Feldstudien wird die mit diesem Projekt zusammengetragene Datensammlung den zurzeit umfassendsten Datensatz für Maar bildende Eruptionen bilden. Dieser einmalige Datensatz, welcher eine erste Schätzung eines Gasbudgets einer Maar-Eruption ermöglicht, wird als Basis für die Interpretation von Schlüsselfaktoren für Maar-bildungen dienen. Dieses Projekt wird somit zu einer exzellenten Fallstudie für die Prognose von Eruptionsverhalten and Gefahrenanalyse für zukünftige Eruptionen von kleinvolumigen vulkanischen Feldern.

 

Direct link to Lay Summary Last update: 19.01.2015

Responsible applicant and co-applicants

Employees

Publications

Publication
Arrested diatreme development: Standing Rocks East, Hopi Buttes, Navajo Nation, USA
Lefebvre Nathalie (2015), Arrested diatreme development: Standing Rocks East, Hopi Buttes, Navajo Nation, USA, in Journal of Volcanology and Geothermal Research, 310, 186-208.

Collaboration

Group / person Country
Types of collaboration
Eau Terre Environnement Research Centre / INRS Canada (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Department of Earth Sciences / University of Otago New Zealand (Oceania)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Geological Survey of Canada Canada (North America)
- Publication
School of Earth Sciences, Northern Arizona University United States of America (North America)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Department of Geosciences, University of Fribourg Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
- Research Infrastructure
Department of Earth and geo-environmental sciences /Università degli Studi di Bari Aldo Moro Bari Italy (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
International Association of Volcanology and Chemistry of the Earth's Interior Conference Poster Textural and morphological studies of juvenile pyroclasts from the Ukinrek maars, Alaska: Insights into variation in eruption style of mafic monogenetic volcanoes 14.08.2017 Portland, Oregon, United States of America Lefebvre Nathalie;
Argentine Geological Congress Talk given at a conference Overview of the Cerro Chivo Volcanic Field (CCVF), Chubut Province, Argentina: basalt sheets, root zones, diatremes and ‘plugs’ 07.08.2017 San Miguel de Tucumán, Argentina Lefebvre Nathalie;
Geosciences New Zealand annual conference Poster Repeatedly Monogenetic Maars and a River: Cerro Carran and its Neighbors, Chile 28.11.2016 Wanaka, New Zealand Lefebvre Nathalie;


Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
Retirement Ceremony for Professor Georg Buechel, Jena University Talk 14.10.2016 Jena, Germany Lefebvre Nathalie;


Abstract

Maar-diatreme volcanoes, the second most common volcano type on continents, produce the most violent eruptions of small-volume basaltic systems. Several populated cities are built within active volcanic fields that contain maar volcanoes, thus such eruptions can cause destruction of life and infrastructure resulting in serious socio-economic implications. However, the factors that govern these eruptions are still poorly constrained. Furthermore, maar eruptions and monogenetic volcanoes in general, can display variations in eruption intensity at the onset and during an eruption making eruption behavior predictions for hazard assessment challenging. The aim of this study is to link surface deposits and eruption dynamics to shallow volcanic processes to better constrain potential factors responsible for maar-eruptions and variations in eruption intensity. Specifically, it focuses on determining volatile budget estimates, and degassing, crystallization and fragmentation histories of the most recent and best-monitored maar-eruption in the world, the Ukinrek 1977 eruption. This is an ideal study area as eruption durations, eruption column behavior and hydrogeology, that must usually be inferred, are reasonably well constrained and there is a sound geological framework from extensive field studies of the tephra deposits to build upon. In addition, Ukinrek demonstrated complexity in eruption intensity shown by simultaneous phreatomagmatic and scoria cone-forming eruptions from two vents within the same maar. Thus, it is also an optimal locality to compare in detail deposits of different eruption intensity originating from the magma source. Volatile types (CO2, H2O, S, F, Cl), and concentrations will be measured from melt inclusions and matrix glass analyses using Fourier Transform Infra-Red Spectrometry, Karl Fischer Titration, carbon analyzer, Electron Microprobe and Secondary Ion Mass Spectrometry. Juvenile pyroclast morphological parameters, which provide information on the nature of the magma during fragmentation, will be determined from image analysis of Scanning Electron Microscope images and Scanning Electron Microscope micro-Computed tomography using the fractal-dilation method. Textural studies of juvenile pyroclasts to determine the degassing and crystallization histories from vesicle and crystal populations will be quantified using FE-Scanning Electron Microscopy, X-ray Computer Tomography, Scanning Electron Microscope micro-Computer Tomography, and statistical stereology. Whole rock, melt inclusion and matrix glass major and trace element compositions, which are essential for understanding how a magma evolves during an eruption, will be analyzed using an Electron Microprobe, X-ray Fluorescence and Laser Ablation Induced Couple Plasma Mass Spectroscopy. This research, together with previous field studies and documentation of the eruption, will build the most comprehensive and integrative data set for a maar-forming eruption to date. It will be the basis for interpretation of the key drivers for maar formation and how shallow subvolcanic processes can lead to eruptive complexity at the surface. Furthermore, this research will provide an excellent case study for eruption behavior predictions and hazard assessment of future maar-forming eruptions.
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