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July 2012 - present
Publications
Publications (63)
Viscosity is a fundamental physical property of lava that dictates style and rate of effusive transport. Studies of lava viscosity have predominantly focused on measuring re-melted rocks in the laboratory. While these measurements are well-constrained in temperature, shear rate, and oxygen fugacity, they cannot reproduce the complexities of the nat...
Hawaiian lava fountains produce a wide variety of pyroclasts, including achneliths, i.e., fluidal juvenile fragments. These range from nearly perfect spheres to very elongate Pele’s hairs, but the controls on such variations are not yet entirely clear. We therefore conduct laboratory-scale experiments using magmas of three different compositions (o...
Pre-mixing of magma and external water plays a key role in driving explosive phreatomagmatic and submarine volcanic eruptions. A thin film of water vapor forms at the magma–water interface as soon as hot magma comes in direct contact with the cold water (Leidenfrost effect). The presence of a stable vapor film drives efficient mixing and mingling b...
Blasting experiments were performed that investigate multiple explosions that occur in quick succession in unconsolidated ground and their effects on host material and atmosphere. Such processes are known to occur during phreatomagmatic eruptions at various depths, lateral locations, and energies. The experiments follow a multi‐instrument approach...
Investigating the conditions behind the formation of pyroclast textures and lava flow morphologies is important to understand the dynamics of submarine volcanic eruptions, which are hard to observe. The development of clast textures and lava morphologies depends on the competing effects of their eruption rates and the rates of solidification. While...
Primary magma fragmentation in “fluid-dominated” (as opposed to “ash-dominated”) lava fountains involves the hydrodynamic breakup of a jet of magma. Lava fountains partly resemble industrial liquid jets issued from a nozzle into a quiescent atmosphere, on which there is a vast literature. Depending on the internal liquid properties, nozzle diameter...
Blasting experiments were performed that investigate multiple explosions that occur in quick succession in the ground and their effects on host material and atmosphere. Such processes are known to occur during volcanic eruptions at various depths, lateral locations, and energies. The experiments follow a multi-instrument approach in order to observ...
The cooling rate of magma in the presence of external water during phreatomagmatic and submarine eruptions is one of the key parameters governing non-explosive to explosive magma fragmentation and eruption transitions, but remains poorly constrained. Combining results from laboratory experiments with realistic eruptive temperatures of magma cooling...
Shallow and subaerial volcanic processes radiate infrasound directly into the atmosphere; sampling these infrasound complement seismic data and aids with physical quantification of explosive eruption mechanisms. More advanced quantitative models of the infrasonic source and associated seismo-acoustic wave conversion and coupling have the potential...
Interaction of magma with groundwater or surface water can lead to explosive phreatomagmatic eruptions. Questions of this process center on effects of system geometry and length and time scales, and these necessitate experiments at larger scale than previously conducted in order to investigate the thermohydraulic escalation behavior of rapid heat t...
Multidisciplinary Volcano Hazards Experiments at the Geohazards Field Station; Amherst and Springville, New York, 24–27 July 2018
The knowledge of the cooling time scales of pyroclasts, in conditions of free to forced convection, is of paramount importance in microtextural analysis, development of welded deposits, and in eruption column and pyroclast flow modeling. We performed cooling experiments of heated rock inside a cylindrical wind tunnel under a range of air speeds. In...
One mechanism for generating lahars at volcanoes experiencing unrest is the disruption of internal aquifers. These disruptions can trigger releases of large quantities of groundwater. An example of such aquifer disruption occurred at Nevado del Huila Volcano, Colombia, during February and April 2007 when large fractures formed across the summit are...
Recent work is changing our understanding of phreatomagmatic maar-diatreme eruptions and resulting deposits. In previous models, explosions were often inferred to take place only at the base of a diatreme, with progressive downward migration due to a cone of depression in the host aquifer. However, diatremes themselves contain much water that is he...
Eruptions through debris-filled vents produce deposits containing magmatic juvenile lithic and recycled clasts. Recycled clasts are exposed to multiple transportation and fragmentation events. We used experiments with multiple subsurface explosions to track clasts and highlight dominant recycling processes in eruptions through analog debris-filled...
Experiments simulating processes operating in volcano-ice interactions were carried out to explain and quantify lava thermal properties and processes of heat transfer from pure lava melt to water and ice and from hot crystalline lava to water. The samples used (70-200 g) were obtained from intermediate lava flow (benmoreite-trachyte) that was empla...
While the relationship between the host-substrate properties and the formation of maar-diatreme volcanoes have been investigated in the past, it remains poorly understood. In order to establish the effects of the qualitative host-substrate properties on crater depth, diameter, morphological features, and sub-surface structures, we present a compari...
Circumferential variation in sorting, thickness, granulometry, and componentry of tephra ring deposits can result from instabilities in the eruptive jet and interactions with the confining crater. Jet instabilities result in fingers of high particle concentrations that form deposits radiating away from a crater, referred to as rays. Two major types...
Most volcanic explosions leave a crater in the surface around the center of the explosions. Such craters differ from products of single events like meteorite impacts or those produced by military testing because they typically result from multiple, rather than single, explosions. Here we analyze the evolution of experimental craters that were creat...
The volume, grain size, and depositional facies of
material deposited outside an explosion crater, ejecta, are sensitive
to the depth of the explosion, the explosion energy, and
the presence or absence of a crater before the explosion. We
detonate buried chemical explosives as an analog for discrete
volcanic explosions in experiments to identify un...
We present results of experiments that use small chemical explosive charges buried in layered aggregates to simulate the effects of subsurface hydrothermal and phreatomagmatic explosions at varying depths and lateral locations, extending earlier experimental results that changed explosion locations only along a vertical axis. The focus is on the re...
The source conditions of volcanic plumes and collapsing fountains are investigated by means of large-scale experiments. In the experiments, gas-particle jets issuing from a cylindrical conduit are forced into the atmosphere at different mass flow rates. Dense jets (high particle volumetric concentration, e.g., C 0 > 0.01) generate collapsing founta...
Subsurface phreatomagmatic explosions can result from the interaction of ascending magma with groundwater. Experiments over a wide range of energies show that for a given energy there is a depth below which an explosion will be contained within the subsurface (not erupt), and there is a corresponding shallower depth that will optimize ejecta disper...
Explosive eruptions are characterized by the fast release of energy, with gas expansion playing a lead role. An
excess of pressure may be generated either by the exsolution and accumulation of volatiles (e.g., vulcanian and strombolian explosions) or by in situ vaporization of water (e.g., phreato-magmatic explosions). The release of pressurized ga...
Infrasound and high speed imaging during a series of field-scale buried explosions suggest new details about the generation and radiation patterns of acoustic waves from volcanic eruptions. We recorded infrasound and high speed video from a series of subsurface explosions with differing burial depths and charge sizes. Joint observations and modelin...
Basaltic maar-diatreme volcanoes, which have craters cut into pre-eruption landscapes (maars) underlain by downward-tapering bodies of fragmental material commonly cut by hypabyssal intrusions (diatremes), are produced by multiple subsurface phreatomagmatic explosions. Although many maar-diatremes have been studied, the link between explosion dynam...
Ballistics - bomb-sized pyroclasts that travel from volcanic source to final emplacement position along ballistic trajectories - represent a prime source of volcanic hazard, but their emplacement range, size, and density is useful to inverse model key eruption parameters related to their initial ejection velocity. Models and theory, however, have s...
Detailed analysis of volcanic craters and ballistic deposits can provide insight into eruption dynamics and evolution. As fully exposed craters and associated unmodified deposits are rarely preserved, the dynamics involved can only be inferred. Large-scale blast experiments conducted at the University at Buffalo Geohazards Field Station produced de...
In an ongoing effort to understand the relevant processes behind the formation of volcanic crater-, maar-, and diatreme structures, experiments producing craters with radii exceeding one meter were conducted at University at Buffalos Geohazards Field Station. A chemical explosive was used as energy source for the tests, and detonated in prepared te...
Volcanic craters are often formed by multiple subsurface explosions caused by the interaction of magma and groundwater [Lorenz, 1973; Valentine and White, 2012]. To understand the processes and products of such explosions, scientists spent 2 years conducting experiments that produced craters on the meter scale at the Geohazards Field Station in Ash...
The source conditions and the subsequent dynamics of volcanic
plumes and collapsing fountains are investigated by means of
large-scale experiments. From the experiments, gas-particle jets
issuing from a cylindrical conduit are forced entering the
atmosphere by a variable mass flow rate. Dense jets (high
particle volumetric concentration, e.g. C > 0...
The source conditions of volcanic plumes and collapsing fountains are investigated by means of large-scale
experiments. On experiments, gas-particle jets issuing from a cylindrical conduit are forced into the atmosphere by a variable mass flow rate. Dense jets (high particle volumetric concentration) generate collapsing fountains whose height scale...
Maar–diatreme eruptions are hazardous to people and infrastructure, and are also linked to the formation of the kimberlitic variety of diatremes, which is important economically. Processes occurring in the subsurface diatreme and their relation to surface eruptions are not yet well understood. We conducted field-scale experiments using analog mater...
Most volcanic eruptions occur in craters formed by previous activity. The presence of a crater implies specific confinement geometries, variably filled by loose fragmental deposits, which are expected to exert a strong, yet poorly studied, control on the violent gas expansion that drives the eruption. Here we analyze patterns of ejection from burie...
Recent observations have shattered the long-held theory that deep-sea (>500 m) explosive eruptions are impossible; however, determining the dynamics of unobserved eruptions requires interpretation of the deposits they produce. For accurate interpretation to be possible, the relative abilities of explosive magmatic degassing and non-explosive magma–...
Craters at many volcanoes, including most maars, are formed by multiple
subsurface explosions. Experiments compared the crater formed by a
single large, buried explosion, with craters formed by multiple
explosions with the same cumulative energy. Explosive charges were
detonated in pads composed of layered aggregates, in three
configurations: (1) a...
Experiments in volcano-ice interaction are carried out to explain and quantify processes of heat transfer from magma to water and ice in phreatomagmatic and subglacial eruptions. Special emphasis is placed on laboratory experiments using re-melted rocks and ice as well as heated rocks and water. Settings studied are: (1) lava-ice contact where magm...
The recent eruptions of Eyjafjallajökull and Grimsvötn
volcanoes in Iceland demonstrate the importance of a better
understanding of processes leading to the formation of volcanic ash,
specifically of fine volcanic ash that poses a threat to air traffic.
Continuous deformation and brittle-type experiments were carried out to
better constrain these p...
Surtseyan tephra jets, also called cypressoid or cock's tail plumes,
comprise a characteristic mixture of ash with bombs travelling roughly
ballistic paths that tip the individual fingers of the projecting jet.
Jets of similar form but smaller scale are generated by littoral
magma-water interactions, confirming the general inference that
surtseyan...
Much of the volcanism on Earth takes place in subaqueous settings where magma has direct contact with a water reservoir of restricted or quasi unrestricted volume. In order to assess the intensity and timescale of non-explosive interaction of magmatic melts and water, experiments representing these settings were performed. Natural volcanic samples...
Experiments in volcano-ice interaction were carried out to explain and quantify processes of heat transfer from magma to water and ice in phreatomagmatic and subglacial eruptions. Special emphasis was placed on laboratory experiments using re-melted rocks and ice. Settings studied so far are: (1) lava-ice contact where magma or hot rocks and ice ha...
The presence of water at volcanic vents can have dramatic effects on fragmentation and eruption dynamics, but little is known about how the presence of particulate matter in external water will further alter eruptions. Volcanic edifices are inherently “dirty” places, where particulate matter of multiple origins and grainsizes typically abounds. We...
A basic experimental study of the behavior of magma rheology was carried out on remelted volcanic rocks using wide gap viscometry. The complex composition of magmatic melts leads to complicated rheologic behavior which cannot be described with one simple model. Therefore, measurement procedures which are able to quantify non-Newtonian behavior have...
Compared to “dry” atmospheric eruption of magma or “dry” magma/rock contact, intensity and time scale of heat discharge from magma to the surroundings is strongly modified by an effective coolant: water or water-sediment mixes. In the case of subaqueous or subglacial eruptions magma-water contact must take place and can result in phreatomagmatic ex...
This work presents a new method to measure model independent viscosities of inhomogeneous materials at high temperatures. Many mechanisms driving volcanic eruptions are strongly influenced by the viscous properties of the participating materials. Since an eruption takes place at temperatures at which these materials (predominantly silicate melts) a...
Pyroclastic flows represent the most hazardous events of explosive volcanism, one striking example being the famous historical eruption of Vesuvius that destroyed Pompeii (AD 79). Much of our knowledge of the mechanics of pyroclastic flows comes from theoretical models and numerical simulations. Valuable data are also stored in the geological recor...
Pyroclastic flows are ground hugging, hot, gas-particle flows. They represent the most hazardous events of explosive volcanism, one striking example being the famous historical eruption of Pompeii (AD 79) at Vesuvius. Much of our knowledge on the mechanics of pyroclastic flows comes from theoretical models and numerical simulations. Valuable data a...
Accepted for publication in (Geophysical Research Letters). Copyright (2009) American Geophysical Union. It is currently impractical to measure what happens in a volcano during an explosive eruption, and up to now much of our knowledge depends on theoretical models. Here we show, by means of large-scale experiments, that the regime of explosive eve...
When a magmatic melt encounters water, heat is transferred and in many cases the melt is fragmented to varying degrees by a range of processes. Explosive MFCI interactions result from extremely rapid heat transfer during fine fragmentation. Under other conditions, interactions extend from quiet steaming to non- explosive granulation. Among the many...
The release of kinetic energy during explosive volcanic eruptions is a key parameter for hazard assessment and civil defense. The explosive production of volcanic ash by intensive fragmentation of magma and host rocks represents a substantial part of this energy. For cases of explosive eruption where predominantly host rock was fragmented (phreatom...
Basaltic melt drives most of earth's volcanism. Understanding its rheology is crucial for any model of magma transport and volcanic eruption. Basaltic magma is generally treated as a quasi Newtonian liquid, but there are observations of Non-Newtonian behaviour. With a method, that allows measurement of Non-Newtonian viscosity of a representative me...
