Iain Matthew Watson

• PhD
• Lecturer at University of Bristol

This paper discusses a method of determining the minimum safe altitude of an uncrewed aerial vehicle (UAV) at any point within a designated airspace by conducting a glide reachability analysis. Recently, fixed‐wing UAVs are more regularly deployed near population centers and in extreme environments, requiring increasingly robust emergency systems a...

This paper presents a method for coordinating volcanic plume interception using a fixed wing Unmanned Aerial Vehicle (UAV), developed for practical use over Volcan de Feugo, Guatemala. A series of techniques have previously been developed for operating in this area, spanning 60 flights since February 2017, targeting the collection of ash from withi...

Volcanic emissions are a critical pathway in Earth's carbon cycle. Here, we show that aerial measurements of volcanic gases using unoccupied aerial systems (UAS) transform our ability to measure and monitor plumes remotely and to constrain global volatile fluxes from volcanoes. Combining multi-scale measurements from ground-based remote sensing, lo...

Uncertainty estimates are important when retrieving properties of clouds and aerosols from satellites measurements. These measurements must be interpreted using a form of inverse theory, such as optimal estimation. In atmospheric remote sensing these inverse methods often assume that the forward model is linear in the region of uncertainty. This as...

In recent years, the London Volcanic Ash Advisory Center (VAAC) conducted a study for monitoring volcanic ash clouds using the Lagrangian atmospheric dispersion model called NAME (Numerical Atmospheric Dispersion Modeling Environment). The objective of this chapter is to investigate and enhance the predictive ability of the NAME‐III dispersion mode...

This study presents a photogrammetric method for 3D reconstruction of a volcanic plume outline to retrieve its spatial properties. A dataset of sequential multi-view images was collected, using a drone-mounted camera, for a small-scale volcanic plume emitted from Volcán Pacaya, Guatemala. A ‘Space Carving’ algorithm has been applied to estimate the...

Actividad histórica Volcán de Fuego es conocido por la constancia de su actividad, que se manifiesta en erupciones estrombolianas frecuentes intercalados con eventos mas fuertes como la del octubre 1974. Desde el principio de 2015 ha empezado un nuevo ciclo de actividad que consiste en paroxismos con efusión de lava 2. La erupción más reciente de e...

A team from the University of Bristol have developed a method of operating fixed wing Unmanned Aerial Vehicles (UAVs) at long-range and high-altitude over Volcán de Fuego in Guatemala for the purposes of volcanic monitoring and ash-sampling. Conventionally, the mission plans must be carefully designed prior to flight, to cope with altitude gains in...

This study presents a method and a proof of principle system for the direct measurement of volcanic plume 3-D spatial properties. The shape of a plume is reconstructed in three dimensions using multi-view imagery collected from static ground-based cameras. The method was developed using data collected during an expedition to Volcán de Fuego in Guat...

This paper describes a series of proof‐of‐concept Beyond Visual Line Of Sight unmanned aerial vehicle flights which reached a range of up to 9 km and an altitude of 4,410 m Above Mean Sea Level over Volcán de Fuego in Guatemala, interacting with the volcanic plume on multiple occasions across a range of different conditions. Volcán de Fuego is an a...

Lahar generation has been linked with excessive rainfall in seasonal-tropic volcanic areas. However, the exact dynamics of how lahars are affected by external factors are often lesser touched upon. In this study, it is proven that voluminous eruptions (VEI > 3) produces lahars almost instantly. After which laharic frequency decreases exponentially...

Volcanic gas emissions are intimately linked to the dynamics of magma ascent and outgassing, and, on geological timescales, constitute an important source of volatiles to the Earth's atmosphere. Measurements of gas composition and flux are therefore critical to both volcano monitoring and to determining the contribution of volcanoes to global geoch...

Volcán de Fuego is a stratovolcano in Guatemala that has produced over 50 VEI ≥ 2 eruptions since 1524. After two decades of quiescence, in 1999 Fuego entered a new period of eruptive activity that continues until the present day, characterized by persistent Strombolian activity interspersed with occasional “paroxysmal” eruptions of greater magnitu...

This paper discusses how epistemic uncertainties are considered in a number of different natural hazard areas including floods, landslides and debris flows, dam safety, droughts, earthquakes, tsunamis, volcanic ash clouds and pyroclastic flows, and wind storms. In each case it is common practice to treat most uncertainties in the form of aleatory p...

Part 1 of this paper has discussed the uncertainties arising from gaps in knowledge or limited understanding of the processes involved in different natural hazard areas. Such deficits may include uncertainties about frequencies, process representations, parameters, present and future boundary conditions, consequences and impacts, and the meaning of...

Part 1 of this paper has discussed the uncertainties arising from gaps in knowledge or limited understanding of the processes involved in different natural hazard areas. Such deficits may include uncertainties about frequencies, process representations, parameters, present and future boundary conditions, consequences and impacts, and the meaning of...

This paper discusses how epistemic uncertainties are currently considered in the most widely occurring natural hazard areas, including floods, landslides and debris flows, dam safety, droughts, earthquakes, tsunamis, volcanic ash clouds and pyroclastic flows, and wind storms. Our aim is to provide an overview of the types of epistemic uncertainty i...

Volcán de Fuego (Guatemala) erupted explosively with unusual intensity, producing widespread ash dispersal and pyroclastic flows of N11 km length, which destroyed a community on Fuego's flanks, causing hundreds of fatalities. Here, we analyze satellite measurements of the SO 2 plume emitted during the most intense eruptive phase. Key eruption param...

Pacaya volcano in Guatemala is one of the most active volcanoes of the Central American Volcanic Arc (CAVA). However, its magmatic gas signature and volatile output have received little attention to date. Here, we present novel volcanic gas information from in-situ (Multi-GAS) and remote (UV camera) plume observations in January 2016. We find in-pl...

Atmospheric natural hazards pose a risk to people, aircraft and infrastructure. Automated algorithms can detect these hazards from satellite imagery so that the relevant advice can be issued. The transparency and adaptability of these automated algorithms is important to cater to the needs of the end user, who should be able to readily interpret th...

This poster describes a preliminary study of eruptive activity at Volcán de Fuego in southern Guatemala during the period 2015 - 2017. The poster identifies and describes recurrent above-background explosive eruptions ("paroxysms") through seismic and thermal satellite datasets.

Active volcanoes can be incredibly dangerous, especially to those who live nearby, but how do you get close enough to observe one in action? Matthew Watson explains how artificial drones are providing volcanologists with insights that could one day save human lives

Remote sensing data and the application of geo-spatial technologies have progressively been built into real-time volcanic hazard assessment. Remote sensing of volcanic processes provides a unique synoptic view of the developing hazard, and provides insights into the ongoing activity without the need for direct, on-the-ground observations. Analysis...

Fumaroles are the surface manifestation of hydrothermal circulation and can be influenced by magmatic, hydrothermal, hydrological and tectonic processes. This study investigates the temporal changes in fumarole temperatures and spatial extent on Aluto, a restless volcano in the Main Ethiopian Rift (MER), in order to better understand the controls o...

In this chapter, in situ measurements of airborne ash from manned aircraft are presented, and best practice for aircraft choice and sampling strategy, particularly around the use of optical particle counters (OPCs), is discussed. Results are described from in situ measurement campaigns from Eyjafjallajökull, Grímsvötn, Holuhraun, and Sakurajima. Th...

Deliberate injection of aerosol particles into the stratosphere is a potential climate engineering scheme. Particles injected into the stratosphere would scatter solar radiation back to space, thereby reducing the temperature at the Earth's surface and hence the impacts of global warming. Minerals such as TiO2 or SiO2 are among the potentially suit...

Deliberate injection of aerosol particles into the stratosphere is a potential climate engineering scheme. Particles injected into the stratosphere would scatter solar radiation back to space, thereby reducing the temperature at the Earth's surface and hence the impacts of global warming. Minerals such as TiO$_{2}$ or SiO$_{2}$ are among the potent...

Deliberate injection of aerosol particles into the stratosphere is a potential climate engineering scheme. Particles injected into the stratosphere would scatter solar radiation back to space, thereby reducing the temperature at the Earth's surface and hence the impacts of global warming. Minerals such as TiO2 or SiO2 are among the potentially suit...

Effective modelling of atmospheric volcanic ash dispersion is important to ensure aircraft safety, and has been the subject of much study since the Eyjafjallajökull ash crisis in Europe in 2010. In this paper, a novel modelling method is presented, where the atmospheric transport of the 2011 Grímsvötn ash cloud is simulated using a data insertion u...

Deliberate injection of aerosol particles into the stratosphere is a potential climate engineering scheme. Introduction of particles into the stratosphere would scatter solar radiation back to space, thereby reducing the temperature at the Earth’s surface and hence the impacts of global warming. Minerals such as TiO2 or SiO2 are among the potential...

Volcanic Ash: Hazard Observation presents an introduction followed by four sections, each on a separate topic and each containing chapters from an internationally renowned pool of authors. The introduction provides a volcanological context for ash generation that sets the stage for the development and interpretation of techniques presented in subse...

This study demonstrates a method of retrieving the mass column loading and cloud-top pressure of a volcanic ash cloud, together with the effective radius and spread of the ash particle size distribution, as well as the cloud top pressure of any underlying water cloud, using an optimal estimation technique applied to Infrared Atmospheric Sounding In...

This paper discusses how epistemic uncertainties are considered in a number of different natural hazard areas including floods, landslides and debris flows, dam safety, droughts, earthquakes, tsunamis, ash clouds, pyroclastic flows and wind storms. In each case it is common practice to treat most uncertainties in the form of aleatory probability di...

There are many good reasons to study and observe gaseous emissions from volcanoes. Quantitative measurements provide insights into volcanic processes occurring deep within a volcano, at more shallow levels where gases exsolve from magma and escape via fissures and cracks, into eruption processes at the surface and within the atmosphere. Emission ra...

Volcanism has been an unrivaled contributor of material to the atmosphere over the course of Earth history. Emissions from volcanoes can include gases, liquid droplets, and solid particles across a wide range of chemical variation. The primary products from active volcanism are water (in three phases), carbon dioxide, and lithic fragments derived f...

Remote sensing can be defined as ‘‘study of a target (object or phenomenon) where no physical contact with that target is made.’’ Instead of deriving information from direct contact, the effects of the target on the sensor, typically through some change in the information perceived, are used to derive information about the object or phenomenon. Tou...

Ambitious response needed on climate front Letter to the Times – 16 th Dec 2015 Sir, The agreement reached in Paris shows there is now impressive global ambition to tackle climate change – with tough challenges ahead (Britain facing steeper emissions cuts; Dec 14). Further policy action is urgently required to transform ambition into reality. Unfor...

Uncertainties in natural hazard risk assessment are generally dominated by the sources arising from lack of knowledge or understanding of the processes involved. There is a lack of knowledge about frequencies, process representations, parameters, present and future boundary conditions, consequences and impacts, and the meaning of observations in ev...

Despite the similar spectral signatures of ash and desert dust, relatively little has been done to explore the application of dust detection techniques to the problem of volcanic ash detection. The Saharan dust index (SDI) is routinely implemented for dust monitoring at some centres and could be utilised for volcanic ash detection with little compu...

This work provides a sensitivity study of a two-channel passive infrared remote sensing retrieval of effective radius and optical depth using the Spinning Enhanced Visible and Infrared Imager with channels centred at 10.8 and 12.0 μm and a look-up table approach to calculate mass column loading. The retrieval is applied to images of two ash clouds...

Volcanic ash can travel great distances and sometimes persist for several weeks, necessitating the monitoring of large areas for potential aviation hazards. Ash can affect aircraft in several ways, from engine failure to manageable impacts if the ash concentration is low. The location and properties of even low levels of ash are, therefore, require...

To judge the safety of flying during an eruption, the airline industry cannot just rely on advances in volcanic monitoring and prediction, says Matthew Watson.

The session ‘Atmospheric Emissions from Volcanoes’ formed part of the 2014 General Assembly of the Europe-an Geosciences Union (EGU), held in Vienna from 27 April to 2 May. This special issue presents some of the work that was discussed during the session. [...]

div class="page" title="Page 1"> During the eruption of Eyjafjallajökull in April and May 2010, the London Volcanic Ash Advisory Centre demonstrated the importance of infrared (IR) satellite imagery for monitoring volcanic ash and validating the Met Office operational model, NAME. This model is used to forecast ash dispersion and forms much of the...

A data insertion method, where a dispersion model is initialized from ash properties derived from a series of satellite observations, is used to model the 8 May 2010 Eyjafjallajökull volcanic ash cloud which extended from Iceland to northern Spain. We also briefly discuss the application of this method to the April 2010 phase of the Eyjafjallajökul...

Silica (SiO2) is an important mineral present in atmospheric mineral dust particles, and the heterogeneous reaction of N2O5 on atmospheric aerosol is one of the major pathways to remove nitrogen oxides from the atmosphere. The heterogeneous reaction of N2O5 with SiO2 has only been investigated by two studies previously, and the reported uptake coef...

The heterogeneous interactions of gas molecules on solid particles are crucial in many areas of science, engineering and technology. Such interactions play a critical role in atmospheric chemistry and in heterogeneous catalysis, a key technology in the energy and chemical industries. Investigating heterogeneous interactions upon single levitated pa...

Airborne volcanic ash can pose a hazard to aviation, agriculture, and both human and animal health. It is therefore important that ash clouds are monitored both day and night, even when they travel far from their source. Infrared satellite data provide perhaps the only means of doing this, and since the hugely expensive ash crisis that followed the...

Injection of aerosol particles (or their precursors) into the stratosphere to scatter solar radiation back into space, has been suggested as a solar-radiation management scheme for the mitigation of global warming. TiO2 has recently been highlighted as a possible candidate particle because of its high refractive index, but its impact on stratospher...

Injection of aerosol particles (or their precursors) into the stratosphere to scatter solar radiation back into space, has been suggested as a solar-radiation management scheme for the mitigation of global warming. TiO2 has recently been highlighted as a possible candidate particle because of its high refractive index, but its impact on stratospher...

The thermal infrared (TIR) wavelength region has proved highly useful for remotely extracting important parameters of volcanic activity, such as the composition, texture, and temperature of either the surface or gas/aerosol emissions. However, each of these characteristics can vary within the area of one pixel of a remote sensing dataset. which ult...

The monitoring of volcanic ash in the atmosphere by satellite-borne instruments is highly important for generation of warnings of potential ash hazards to aviation, and to constraining model predictions of an ash cloud’s anticipated evolution. The high economic cost of flight restrictions creates a demand for precise monitoring and forecasting; howe...

The stratospheric injection of aerosols is a geoengineering scheme designed to reduce the impacts of climate change. The injected particles scatter solar radiation back to space and hence reduce the radiative forcing of the Earth. The scattering ability of a particle depends on both its size and composition. Particles composed of titania (TiO2) hav...

Dynamic global vegetation models (DGVMs) offer explicit representations of the land surface through time and have been used to research large-scale hydrological responses to climate change. These applications are discussed and comparisons of model inputs and formulations are made among and between DGVMs and global hydrological models. It is shown t...

The deliberate injection of particles into the stratosphere has been suggested as a possible geoengineering scheme to mitigate the global warming aspect of climate change. Injected particles scatter solar radiation back to space and thus reduce the radiative balance of Earth. Previous studies investigating this scheme have focused primarily on sulp...

The advection–diffusion model TEPHRA2 has been used in conjunction with the downhill simplex method (DSM) and one-at-a-time (OAT) inversion methods to reconstruct the eruption conditions and seasonality consistent with the deposit patterns from the Bronze Age (‘Minoan’) eruption of Santorini. We investigated three datasets representing different de...

Volcanic degassing is a major contributor to the global sulphur dioxide (SO2) budget, characterized by quiescent emissions in the lower troposphere with sporadic, spatially variable explosive eruptions into the upper troposphere and lower stratosphere (UTLS). The volcanic input of SO2 to the atmosphere can be quantified using a suite of satellite-b...

Eruptions of intermediate magma may be explosive or effusive. The development of open system degassing has been proposed as a pre-requisite for effusion of intermediate magma, however processes leading to open system degassing are poorly understood. To better understand degassing processes during lava dome extrusion we report high temporal-resoluti...

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a useful tool for detecting low quantities of sulfur dioxide at passively degassing volcanoes such as Lascar volcano, Chile. Two mini-UV spectrometers (MUSes) were used to make transects of Lascar volcano’s sulfur dioxide plume on December 7, 2004, during a coordinated ov...

The eruption of Sarychev Peak Volcano (48°N,153°E), Kuril Islands, occurred between June 12 and 18 2009 emplacing large volumes of sulphur dioxide and volcanic ash into the atmosphere and severely disrupting air traffic in the region. The eruption was observed by several satellite-borne sensors, including the Ozone Monitoring Instrument (OMI), the...

The ash cloud produced by the eruption of Eyjafjallajökull, Iceland during April and May 2010 caused major disruption to European airspace. One of the most significant consequences of the eruption was the introduction of an ash threshold limit, below which ash concentrations are deemed safe for aircraft. If ash dissipates rapidly, and therefore can...

Activity at Santiaguito lava dome is characterised by extrusion of block lava flows, accompanied by regular (0.5-2 h-1) pyroclastic explosions which send gas and ash plumes to heights of 0.5-1.5 km above the dome surface. The trigger mechanism of these events is currently the subject of much debate. Different lines of geophysical evidence have been...

Volcanic eruptions and pyro-convection entrain and transport tropospheric water vapor to the relatively dry stratopshere. Because of natural high abundance of water vapor in the atmosphere and its complex spectroscopic signature, determining the mass of a specific cloud has proven difficult until now. A retrieval to quantify water vapor in the uppe...

We present results from a campaign in March 2009 to assess the current state of emissions from Masaya Volcano, Nicaragua. These results constitute one of the most comprehensive inventories to date of emissions from an active volcano and update the exceptional record of emissions from Masaya. Results from open‐path Fourier transform infrared spectro...

Volcanoes worldwide pose a major threat to humans at both local and global scales. The effective monitoring of volcanoes is essential to manage and reduce risk associated with the threat that they pose. The measurement of volcanic cloud composition can provide important clues to the underlying volcanic processes and can be indicative of impending e...

Activity at Pacaya volcano, Guatemala is characterized by persistent degassing, coupled at times with lava effusion and/or coincident Strombolian-style explosions. We used 0.25 Hz sample rate sulfur dioxide emission data from a UV camera and coincident infrasound recordings to investigate the link between varied emission rates and infrasound events...

Volcanic degassing is a major contributor to the global sulphur dioxide (SO2) budget, characterised by permanent quiescent emissions in the lower troposphere punctuated with sporadic and spatially variable explosive eruptions into the upper troposphere and lower stratosphere (UTLS). The Moderate Resolution Imaging Spectroradiometer (MODIS), the Atm...

While the climatic effects of volcanogenic sulphate aerosol in the stratosphere are well characterised, the nature and global impact of sustained tropospheric volcanic degassing is less well understood. In situ measurement of volcanic emissions can be used to understand plume processes (e.g., microphysics and chemistry), and used to validate and im...

Digital cameras, sensitive to specific regions of the ultra-violet (UV) spectrum, have been employed for quantifying sulfur dioxide (SO2) emissions in recent years. The instruments make use of the selective absorption of UV light by SO2 molecules to determine pathlength concentration. Many monitoring advantages are gained by using this technique, bu...

Passively degassing volcanoes contribute a climatologically significant quantity of sulfur dioxide (SO2) to the atmosphere. Both the Advanced Thermal Emission and Reflection Radiometer (ASTER) and the Ozone Monitoring Instrument (OMI) are capable of detecting emissions from volcanoes in a non-eruptive state. There are fundamental differences betwee...

The split window algorithm, or more accurately its application to volcanic ash cloud detection, is twenty years old this year. Often applied, and much maligned, the split-window algorithm has changed little since its first application, due primarily to radiometric limits on infrared satellite sensors. However, the advent of hyperspectral imagery, f...

Previous studies have suggested that the presence of silicate ash may cause the 8.6-μm sulfur dioxide (SO2) retrieval to overestimate total column abundances and contribute to variations between ultraviolet and 8.6-μm SO2 estimates. Tested here is a volcanic aerosol forward model which allows the determination of transmission spectra. The forward m...

Sulphur dioxide retrievals of three satellite-based sensors (the Total Ozone Mapping Spectrometer, the Ozone Monitoring Instrument and the Moderate Resolution Imaging Spectroradiometer) were performed on the volcanic cloud from the Sierra Negra, Galápagos Islands eruption of October 22 to October 30, 2005. Near-coincidental plume acquisitions on 23...

The detection of SO2 plumes by space-based sensors has been demonstrated in the UV and TIR. However, the relationship between these retrieval techniques is poorly constrained. In this paper we compare near-coincidental EP TOMS and MODIS data of a near-pure SO2 plume from the Al-Mishraq State sulfur plant fire on 29 June 2003. We resampled the MODIS...

Airborne dust affects the Earth's energy balance - an impact that is measured in terms of the implied change in net radiation (or radiative forcing, in W m-2) at the top of the atmosphere. There remains considerable uncertainty in the magnitude and sign of direct forcing by airborne dust under current climate. Much of this uncertainty stems from si...

A newly developed ultraviolet (UV) imaging camera offers a new approach to the ground-based surveillance of volcanic sulphur dioxide (SO 2). Using highly sensitive 2-dimensional CCD technology and a bandpass filter centred in the UV region where SO 2 selectively absorbs UV light, the camera is able to quantify SO 2 within a gas plume in great detai...

SO2 emission measurements are an important component of monitoring volcanic eruption processes. Owing mainly to limitations in the temporal resolution of measurements, the goal of merging a gas flux record with other geophysical datasets (seismic, acoustic) with the aim of investigating subsurface processes has been elusive. In recent years, ground...

Airborne mineral dust affects climate through direct and indirect radiative effects, and presents hazards to human health and aircraft. The magnitude of the dust cycle is uncertain and estimates of the global dust burden vary over a factor of 4. In addition, estimates of the dust direct radiative effect disagree in both the sign and magnitude of th...

The North Pacific region contains over 150 active volcanoes which may produce large eruption plumes. Volcanic plumes are composed of various amounts of silicate ash, ice, SO42-, SO2 and other gases, all of which vary in abundance due to initial concentrations, fallout and atmospheric interactions. These cloud components all have specific transmissi...

Recently developed ultraviolet cameras present a significant improvement in the field of volcanic SO2 measurements. Older instruments utilized for measurement of SO2 emissions in volcanic plumes (e.g., COSPEC, mini-DOAS, FLYSPEC) are often limited in their accuracy by plume and volcano geometry, uncertainties in plume velocity, plume variability ov...

From soon after its launch in December 1999, the ASTER sensor on the NASA Terra satellite has been acquiring data of volcanic eruptions and other natural disasters around the world. ASTER has the capability to acquire high spatial resolution data from the visible to thermal infrared wavelength region. Those data, in conjunction with its ability to...

Bezymianny volcano, Kamchatka Peninsula, Russia, is one of the most active volcanoes in the North Pacific (NOPAC) region and erupts violently on average every 6 months. We report the SO2 cloud mass, emission and transport rates for the eruption of Bezymianny on 13–14 January 2004, and discuss the issues associated with determining SO2 production an...

Two significant eruptions occurred at Miyakejima volcano on 18 and 28 August 2000 and were detected by multiple satellite sensors. For both eruptions, the cloud can be observed with high confidence for 2 days. Using Total Ozone Mapping Spectrometer (TOMS), MODerate resolution Infrared Spectroradiometer (MODIS), Advanced Very High Resolution Radiome...

To improve interpretation of volcanic SO2 flux data, it is necessary to quantify and understand reactions involving SO2 in volcanic plumes. SO2 is lost in volcanic plumes through a number of mechanisms. Here we report SO2 measurements made with miniature ultraviolet spectrometers at Soufrière Hills volcano, Montserrat; a low altitude volcano (~ 100...

[1] Santiaguito Volcano, Guatemala, regularly produces small vulcanian eruption plumes which rise to heights of up to 2 km. A combined study using a novel UV camera coupled with classical analysis of the fluid dynamics of finite-volume buoyant releases (thermals) has been used to develop a detection algorithm for ground-based volcanic ash monitorin...

During December 2000 and January 2001, an increase in activity at Popocatépetl volcano, Mexico, was observed in both ground-based correlation spectrometer (COSPEC) data and in imagery from various satellite sensors, including the Moderate Resolution Imaging Spectroradiometer (MODIS), Total Ozone Mapping Spectrometer (TOMS), Advanced Very High Resol...

Measurement of ash particle distribution within volcanic eruption plumes is important for volcanic hazard prediction, but is difficult because of the inherent danger and inaccessibility of volcanoes, and the three-dimensional time-dependent dynamics of turbulent eruption plumes. A combined study using a novel UV camera coupled with classical analys...

Cyclic gas production has been observed at Santiaguito volcano, Guatemala, using differential optical absorption spectroscopy (DOAS) and UV imaging systems. Santiaguito explodes regularly, on the order of once an hour, and produces weak ash plumes, that are mostly buoyancy driven, to an altitude of 1-2 km above its dome. Dara from campaigns in 2004...

In order to develop a detailed understanding of the dynamics of gas puffing (gas release as a series of distinct pulses) and more sustained degassing (steady plumes of gas) during persistent volcanic degassing, measurements of gas mass flux are required in the vicinity of the volcanic vent. Masaya volcano (Nicaragua), a persistently degassing syste...

Techniques used to observe and monitor volcanic ash in order to mitigate aviation hazard require testing to determine their reliability and limitations. Currently, the most used techniques rely on satellite remote sensing and trajectory modeling. Infrared data from such sensors as the Moderate Resolution Imaging Spectroradiometer (MODIS), and the A...

Lascar volcano, Chile, is the most active volcano in the Central Andes region. We conducted field campaigns at Lascar during October-November 2002 and December 2004, using a visible to near infrared Microtops II sun- photometer to measure spectral optical depths in order to infer particle size distributions of volcanic aerosols in the volcanic plum...