Preprints
Filtering by Subject: Volcanology
The architecture of an intrusion in magmatic mush
Published: 2020-01-17
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
Magmatic reservoirs located in the upper crust have been shown to result from the repeated intrusions of new magmas, and spend much of the time as a crystal-rich mush. The geometry of the intrusion of new magmas may greatly affect the thermal and compositional evolution of the reservoir. Despite advances in our understanding of the physical processes that may occur in a magmatic reservoir, the [...]
Logarithmic growth of dikes from a depressurizing magma chamber
Published: 2019-11-13
Subjects: Earth Sciences, Geology, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
Dike propagation is an intrinsically multiphase problem, where deformation and fluid flow are intricately coupled in a fracture process. Here we perform the first fully-coupled simulations of dike propagation in two dimensions, accounting for depressurization of a circular magma chamber, dynamic fluid flow, fracture formation, and elastic deformation. Despite the complexity of the governing [...]
Investigating potential icequakes at Llaima volcano, Chile
Published: 2019-10-24
Subjects: Earth Sciences, Glaciology, Physical Sciences and Mathematics, Volcanology
Glacially- and magmatically-derived seismic events have been noted to heavily overlap in characteristics, thus there exists the potential for false-alarms or missed warnings at ice-covered volcanoes. Here we present the first study to specifically target icequakes at an ice-covered volcano in Southern Chile. Two months of broadband seismic data collected at Llaima volcano in 2015 were analyzed in [...]
Deep and rapid thermo-mechanical erosion by a small-volume lava flow
Published: 2019-10-08
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
We document remarkably efficient thermo-mechanical erosion by a small-volume lava flow. Downcutting by a basaltic-andesite lava flow on the steep-sided Momotombo volcano, Nicaragua, occurred at 100 times the rate commonly reported for thermal erosion in lava flow fields, even though this flow was small-volume (0.02 km^3) and effused at a low rate for <1 week. The erosion depth, up to 30 m [...]
Deep Low-Frequency Earthquakes Associated with the Eruptions of Shinmoe-dake in Kirishima Volcanoes
Published: 2019-10-06
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
Deep low-frequency (DLF) earthquakes occur beneath the Kirishima volcanoes in southwest Japan at depths of 10–30 km. In this study, we aim to reveal the relationship between DLF earthquakes and volcanic activity including eruptions by relocating the hypocenters of the earthquakes using the network correlation coefficient method and detecting the earthquakes comprehensively using the matched [...]
Machine Learning Reveals the Seismic Signature of Eruptive Behavior at Piton de la Fournaise Volcano
Published: 2019-09-30
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
Volcanic tremor is key to our understanding of active magmatic systems but, due to its complexity, there is still a debate concerning its origins and how it can be used to characterize eruptive dynamics. In this study we leverage machine learning (ML) techniques using 6 years of continuous seismic data from the Piton de la Fournaise volcano (La Réunion island) to describe specific patterns of [...]
How do deep-water volcanoes grow?
Published: 2019-09-23
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
Deep-water volcanoes are emplaced in water depths >1.0 km and are widespread along continental margins and in ocean basins. Whilst the external morphology of deep-water volcanoes can be mapped using bathymetric surveys, their internal structure and true volume remain enigmatic. It is thus difficult to determine how deep-water volcanoes grow. We investigate 13 Late Miocene-to-Quaternary, [...]
The near-tip region of a hydraulic fracture with pressure-dependent leak-off and leak-in
Published: 2019-09-03
Subjects: Earth Sciences, Engineering, Environmental Sciences, Hydrology, Oil, Gas, and Energy, Physical Sciences and Mathematics, Volcanology
This paper is concerned with an analysis of the near tip region of a propagating fluid-driven fracture in a saturated permeable rock. The study attempts to accurately resolve the coupling between the physical processes - rock breakage, fluid pressure drop in the viscous fluid flow in the fracture, and fluid exchange between fracture and the rock - that exert influence on the hydraulic fracture [...]
Control of heterogeneous, layered successions on shallow-level magma emplacement and host rock deformation
Published: 2019-08-07
Subjects: Earth Sciences, Physical Sciences and Mathematics, Volcanology
Host rock deformation in active volcanic settings can signal and be used to constrain magma emplacement. Yet it is difficult to evaluate the accuracy of intrusion parameters derived from inversion of deformation signals because we cannot test estimates by directly accessing the magma body. Physical modelling is thus critical to understanding how intrusion translates into host rock deformation, [...]
Seismological evidence for subcrustal magmatic injection beneath Fogo volcano, Cape Verde hotspot
Published: 2019-07-09
Subjects: Earth Sciences, Geophysics and Seismology, Physical Sciences and Mathematics, Volcanology
Fogo volcano belongs to the Cape Verde hotspot and its most recent eruption occurred from November 2014 to February 2015. From January to December 2016 we operated a temporary seismic network on Fogo and were able to locate 289 earthquakes in total. While most of the events occur at distances > 25 km near the neighboring island of Brava. However, on 15th August 2016 we recorded an isolated [...]
The Leaning Puy de Dôme
Published: 2019-07-09
Subjects: Earth Sciences, Geomorphology, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
Acidic lava domes are a special monogenetic volcano type with explosive eruption hazards. Such domes raise questions about the nature of monogenetic volcanism. We study the iconic Puy de Dôme (Chaîne des Puys, Auvergne) that gave its name to dome landforms. It is asymmetric with one side more rugged and steeper than the other. Using mapping and paleomagnetism we find that it was tilted by ~20° [...]
Tectonic stress controls saucer-shaped sill geometry
Published: 2019-07-05
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
Saucer-shaped sills are common in sedimentary basins worldwide. The saucer shape relates to asymmetric stress distributions at the sill-tip during intrusion caused by bending of the overburden. Most saucer-shaped sill models are conducted without tectonic stress. Model results are poorly correlated with natural sills in that: (1) modelled saucers are much steeper than natural sills; and (2) [...]
Finite element simulations of sill intrusion during tectonic loading
Published: 2019-07-05
Subjects: Earth Sciences, Geology, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
Igneous sills are common features in tectonically active regions, acting as nascent magma storage systems, or feeding eruptions at large lateral distances from the magma source. Sills reaching a critical radius, rc, relative to their initial depth, H, interact with Earth’s surface, leading to mild discordant growth at angle [theta] typically <10[deg] forming saucer-shaped sills; commonly [...]
A bedform phase diagram for dense granular currents
Published: 2019-07-04
Subjects: Earth Sciences, Fluid Dynamics, Geology, Physical Sciences and Mathematics, Physics, Sedimentology, Volcanology
Pyroclastic density currents are a life-threatening volcanic hazard. Our understanding and hazard assessments of these flows primarily rely on interpretations of their deposits. The occurrence of stratified layers, cross-stratification, and dune bedforms in these deposits has been assumed as indicative of dilute, turbulent, flows causing traction-dominated deposition. Here we show, through [...]
From prodigious volcanic degassing to caldera subsidence and quiescence at Ambrym (Vanuatu): the influence of regional tectonics
Published: 2019-06-28
Subjects: Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure, Volcanology
Eruptive activity shapes volcanic edifices. The formation of broad caldera depressions is often associated with major collapse events, emplacing conspicuous pyroclastic deposits. However, caldera subsidence may also proceed silently by magma withdrawal at depth, more difficult to detect. Ambrym, a basaltic volcanic island, hosts a 12-km wide caldera and several intensely-degassing lava lakes [...]