Behavior Of Volcanoes Research Articles

Time-Series InSAR Analysis of the Small Baseline Subset to Estimate Surface Deformation at Mt. Bromo Indonesia

Penginderaan jauh kini memainkan peranan penting dalam pengamatan perilaku gunung api. Penelitian ini bertujuan untuk mengamati deformasi permukaan Gunung Bromo, yang terletak di Jawa bagian Timur, Indonesia, yang masuk dalam rangkaian sistem volkanik di Taman Nasional Bukit Tengger Semeru (TNBTS). Penggunaan algoritma SAR Interferometry (InSAR) yang disebut sebagai pendekatan Small Baseline Subset (SBAS) memungkinkan perancangan peta kecepatan deformasi rata-rata dan and peta time series displacement di wilayah kajian. Teknik SBAS yang biasa menghasilkan rangkaian observasi tahap interferometrik. Ini tercatat sebagai kombinasi linear dari nilai fase SAR scene untuk setiap pixel secara tersendiri. Analisis yang dilakukan terutama berdasarkan 22 data SAR data yang diperoleh melalui sensor ALOS/PALSAR selama kurun waktu 2007–2011. Beberapa penelitian menunjukkan bahwa kemampuan analisis InSAR dalam menyelidiki siklus gunung api, terutama Gunung Bromo yang memiliki karakteristik erupsi stratovolcano dalam satu hingga lima tahun. Analisis hasil memperlihatkan adanya kemajuan dari kajian sebelumnya akan InSAR wilayah tersebut, yang lebih fokus kepada deformasi yang berpengaruh kepada kaldera. Hal ini menunjukkan bahwa penelitian ini bisa diimplementasikan pada manajemen risiko atau manajemen infrastruktur

TIME-SERIES SAR INTERFEROMETRY ANALYSIS OF SURFACE DEFORMATION AT MT. BROMO INDONESIA

One of the most active volcanoes in Indonesia is Mt. Bromo, volcanic activities at Mt. Bromo has been recorded in 1775. We observe the surface deformation of the Mt. Bromo which located at eastern Java Indonesia area that includes neighborhood volcanic system on TNBTS (Taman Nasional Bukit Tengger Semeru). Recently, remote sensing has played as an important role to observe volcano behavior. We apply the SAR Interferometry (InSAR) algorithm referred to as Small Baseline Subset (SBAS) approach that allows us to generate mean deformation velocity maps and displacement time series for the studied area. The common SBAS technique, the set of interferometric phase observations writes as a linear combination of individual SAR scene phase values for each pixel independently. Particularly, the proposed analysis is based on 22 SAR data acquired by the ALOS/PALSAR sensors during the 2007–2017 time interval. A fewer studies have been able to show capability of InSAR analysis for investigating cycle of volcano especially of Mt. Bromo which characterized eruption stratovolcano in ranging one to five years. The results expected in this work represent an advancement of previous InSAR studies of the area that are mostly focused on the deformation affecting the caldera. According to the result, we expected this study could implement on risk management or infrastructure management.

Eruption frequency patterns through time for the current (1999–2018) activity cycle at Volcán de Fuego derived from remote sensing data: Evidence for an accelerating cycle of explosive paroxysms and potential implications of eruptive activity

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 magnitude, the most recent of which occurred in 2018. The land surrounding Fuego accommodates tens of thousands of people, so greater understanding of its eruptive behaviour has important implications for hazard assessment. Nevertheless, there is relatively little literature that studies recent (since 1999) activity of Fuego in detail.Using time-series analysis of remote sensing thermal data during the period 2000–2018 combined with recent bulletin reports, we present evidence for a new eruptive regime beginning in 2015. We find that this regime is defined by a greater frequency of paroxysmal eruptions than in previous years and is characterized by the following sequence of events: (i) effusion of lava flows and increase in summit explosive activity, followed by (ii) an intense eruptive phase lasting 24–48 h, producing a sustained eruptive column, continuous explosions, and occasional pyroclastic flows, followed by (iii) decrease in explosive activity. We discuss various models that explain this increase in paroxysmal frequency, and consider its implications for hazard assessment at Fuego. We advocate the pairing of remote sensing data with monitoring reports for understanding long-term changes in behaviour of poorly-instrumented volcanoes. The results that we present here provide a standard for informed assessment of future episodes of unrest and paroxysmal eruptions of Fuego.

Lava Clues Chronicled Kīlauea’s Unusual 2018 Eruption

Samples from Kīlauea volcano’s extraordinary eruption that began last May could offer important insights into the behavior of volcanoes and the underlying mantle.

Understanding Fast and Slow Unrest at Volcanoes and Implications for Eruption Forecasting

This paper examines the behaviour of fast volcanoes that erupt quickly with paroxysmal explosive eruptions, and slow volcanoes that erupt over extended periods without such paroxysmal activity. I review activity at four fast and four slow volcanoes, highlighting the main events and commonalities in behaviour among the different systems. In terms of forecasting, fast volcanoes typically have short 1-3 month precursory periods prior to the climactic eruption, while slow volcanoes commonly have an extended period of considerable uncertainty regarding the presence or absence of new magma, as well as unanticipated accelerations in activity. Fast volcanoes are associated with magmas having elevated volatile contents (up to ~7 wt. % H2O), rapid magma ascent rates, and rapid declines in activity after the climactic eruption. Fast volcanoes also exhibit well defined magma plumbing systems with mobile volatile-rich magma, with the plumbing system sealed between the top of the shallow magma reservoir and the surface prior to the climactic eruption. Slow volcanoes have complex plumbing systems comprising cracks, fractures, dykes, and sills and magmas that are crystal-rich, partly degassed, and rheologically sluggish. Slow volcanoes experience a progressive opening of their systems as magma intrudes and fractures country rock, allowing degassing to occur. The degree to which a system is opened is determined by the rate at which new magma is emplaced at shallow levels. Slower rates of emplacement enhance the opening process due to a cumulatively high number of fractures and increased fracture density which develop during the extended period of unrest. Many systems both fast and slow receive inputs of mafic magma which can drive activity seen at the surface. A series of recently developed tools is examined and discussed in order to provide an improved means of forecasting activity at both types of volcanoes. These include assessment of early phreatic activity and associated gases, Vp /Vs ratios of magma by seismic tomography, and estimates of magma volume from precursory seismicity. What is required now are protocols which integrate these approaches in a manner which is useful for accurate forecasting.

Understanding volcanic hazard at the most populated caldera in the world: Campi Flegrei, Southern Italy

AbstractNaples and its hinterland in Southern Italy are one of the most urbanized areas in the world under threat from volcanic activity. The region lies within range of three active volcanic centers: Vesuvius, Campi Flegrei, and Ischia. The Campi Flegrei caldera, in particular, has been in unrest for six decades. The unrest followed four centuries of quiescence and has heightened concern about an increased potential for eruption. Innovative modeling and scientific drilling are being used to investigate Campi Flegrei, and the results highlight key directions for better understanding the mechanisms of caldera formation and the roles of magma intrusion and geothermal activity in determining the volcano's behavior. They also provide a framework for evaluating and mitigating the risk from this caldera and other large ones worldwide.

Monitoreo volcánico usando plataformas Arduino y Simulink

El monitoreo de la actividad volcánica es una preocupación importante en aquellos países con alto grado de sismicidad. El principal inconveniente es el alto costo de la instrumentación requerida para vigilar el comportamiento de los volcanes, lo cual limita el acceso a información actualizada que permita realizar actividades de prevención. En este trabajo se presenta la implementación de la adquisición de dos variables asociadas al monitoreo volcánico, usando un Arduino y la herramienta Simulink de Matlab. Se implementó un medidor de inclinación o movimiento, que permite medir las deformaciones del edificio volcánico y las posibles sacudidas que pudieran existir de su cono, entre otras aplicaciones. Igualmente se implementó un medidor de temperatura con una termoresistencia PT100. La experimentación permitió comprobar la funcionalidad de los medidores de inclinación y temperatura, arrojando resultados satisfactorios y con errores relativos adecuados. Lo anterior permite concluir que el empleo de Simulink para la programación del Arduino posibilita la simulación y evaluación de los modelos, directamente sobre la placa de Arduino durante el proceso de diseño, con las ventajas que brinda esta alternativa en el ahorro de tiempo y simplicidad en la programación del dispositivo.

Tracking large volcanic eruptions and their regional variability

In order to understand the hazards and risks posed by active volcanoes to modern societies, it is imperative to reconstruct their geologic, historic, and modern records. This information is crucial to decipher volcano behavior over time and the way volcanic unrest may occur. The analysis of all this

Long-term changes in explosive and effusive behaviour at andesitic arc volcanoes: Chronostratigraphy of the Centre Hills Volcano, Montserrat

Volcanism on Montserrat (Lesser Antilles arc) has migrated southwards since the formation of the Silver Hills ~2.5Ma, and has formed three successively active volcanic centres. The Centre Hills volcano was the focus of volcanism from ~1–0.4Ma, before activity commenced at the currently active Soufrière Hills volcano. The history of activity at these two volcanoes provides an opportunity to investigate the pattern of volcano behaviour on an andesitic arc island over the lifetime of individual volcanoes. Here, we describe the pyroclastic stratigraphy of subaerial exposures around central Montserrat; identifying 11 thick (>1m) pumiceous units derived from sustained explosive eruptions of Centre Hills from ~0.8–0.4Ma. Over 10 other, less well- exposed pumiceous units have also been identified. The pumice-rich units are interbedded with andesite lava breccias derived from effusive, dome-forming eruptions of Centre Hills. The stratigraphy indicates that large (up to magnitude 5) explosive eruptions occurred throughout the history of Centre Hills, alongside effusive activity. This behaviour at Centre Hills contrasts with Soufrière Hills, where deposits from sustained explosive eruptions are much less common and restricted to early stages of activity at the volcano, from ~175–130ka. Subsequent eruptions at Soufriere Hills have been dominated by andesitic effusive eruptions. The bulk composition, petrography and mineral chemistry of volcanic rocks from Centre Hills and Soufrière Hills are similar throughout the history of both volcanoes, except for occasional, transient departures to different magma compositions, which mark shifts in vent location or dominant eruption style. For example, the final recorded eruption of Centre Hills, before the initiation of activity at Soufrière Hills, was more silicic than any other identified eruption on Montserrat; and the basaltic South Soufrière Hills episode marked the transition to the current stage of predominantly effusive Soufrière Hills activity. The compositional stability observed throughout the history of Centre Hills and Soufrière Hills suggests that a predominance towards effusive or explosive eruption styles is not driven by major compositional shifts of magma, but may reflect local changes in long-term magma storage conditions that characterise individual episodes (on 105year timescales) of volcanism on Montserrat.

Automatic Recognition of Long Period Events From Volcano Tectonic Earthquakes at Cotopaxi Volcano

Geophysics experts are interested in understanding the behavior of volcanoes and forecasting possible eruptions by monitoring and detecting the increment on volcano-seismic activity, with the aim of safeguarding human lives and material losses. This paper presents an automatic volcanic event detection and classification system, which considers feature extraction and feature selection stages, to reduce the processing time toward a reliable real-time volcano early warning system (RT-VEWS). We built the proposed approach in terms of the seismicity presented in 2009 and 2010 at the Cotopaxi Volcano located in Ecuador. In the detection stage, the recordings were time segmented by using a nonoverlapping 15-s window, and in the classification stage, the detected seismic signals were 1-min long. For each detected signal conveying seismic events, a comprehensive set of statistical, temporal, spectral, and scale-domain features were compiled and extracted, aiming to separate long-period (LP) events from volcano-tectonic (VT) earthquakes. We benchmarked two commonly used types of feature selection techniques, namely, wrapper (recursive feature extraction) and embedded (cross-validation and pruning). Each technique was used within a suitable and appropriate classification algorithm, either the support vector machine (SVM) or the decision trees. The best result was obtained by using the SVM classifier, yielding up to 99% accuracy in the detection stage and 97% accuracy and sensitivity in the event classification stage. Selected features and their interpretation were consistent among different input spaces in simple terms of the spectral content of the frequency bands at 3.1 and 6.8 Hz. A comparative analysis showed that the most relevant features for automatic discrimination between LP and VT events were one in the time domain, five in the frequency domain, and nine in the scale domain. Our study provides the framework for an event classification system with high accuracy and reduced computational requirements, according to the orientation toward a future RT-VEWS.

Linking distal volcaniclastic sedimentation and stratigraphy with the development of Ruapehu volcano, New Zealand

Long-lived stratovolcanoes are often characterized by cycles that include pulses of explosive and effusive eruptive activity, periodic flank collapses, and long periods of eruptive quiescence. Reconstructing these solely from exposures on volcanic edifices is difficult because deposits are dominantly from comparatively recent reconstruction episodes, while older sequences are buried or have long been eroded. Long-runout mass-flow deposits, on the other hand, offer insights into the older eruptive history and long-term eruptive behavior of composite volcanoes. At Mt. Ruapehu, New Zealand, 40Ar/39Ar dating of lava clasts within distal mass-flow sequences, combined with new mapping and sedimentological descriptions, reveal three hitherto unknown eruptive episodes of the volcano and extend its minimum age to at least 340 ka. Plinian to subplinian eruptions were followed by periods of subdued volcanic activity. Voluminous (>1 km3) inter-eruptive flank failures were precursors to major reconstruction episodes, associated with numerous syn-eruptive mass flows emplaced up to 90 km from the volcano. Syn-eruptive collapse triggered large plinian eruptions associated with pyroclastic density currents. Rapid ring-plain aggradation dominated during periods of subdued volcanic activity when intensive edifice erosion induced frequent inter-eruptive lahars.

Isotopic microanalysis sheds light on the magmatic endmembers feeding volcanic eruptions: The Astroni 6 case study (Campi Flegrei, Italy)

Sr-isotopic microanalysis has been performed on selected minerals from the Campi Flegrei caldera, together with Sr and Nd isotopic ratio determinations on bulk mineral and glass fractions. The aim was a better characterization of the chemically homogeneous, but isotopically distinct magmatic components which fed volcanic eruptions of the caldera over the past 5ka, in order to enhance our knowledge about one of the most dangerous volcanoes on Earth.Information on the involved magmatic endmembers, unobtainable by analyzing the isotopic composition of whole rock samples and bulk mineral fractions, has been acquired through high-precision determination of 87Sr/86Sr on single crystals and microdrilled mineral powders. We focused our investigations on the products emplaced during the Astroni 6 eruption (4.23calka BP), assumed representative of the expected event in case of renewed volcanic activity in the Campi Flegrei caldera. Data on single crystals and microdrilled mineral powders have been compared with Sr and Nd isotopic compositions of bulk mineral fractions from products emplaced during the whole Astroni activity, which included seven distinct eruptions. The 87Sr/86Sr ratios of single crystals and microdrilled mineral powders are in the 0.7060 to 0.7076 range, much wider than that of bulk mineral fractions, which range from 0.7066 to 0.7076. Moreover, the Sr isotopic ratios are inversely correlated to 143Nd/144Nd. The new data allow us to better define the magmatic endmembers involved in mingling/mixing processes that occurred prior to/during the Astroni activity. One magmatic endmember, characterized by average 87Sr/86Sr ratio of ~0.70750, was quite common in the past 15ka activity of the Campi Flegrei caldera; the other, as evidenced by the isotopic composition of single feldspar and clinopyroxene crystals, is less enriched in radiogenic Sr (87Sr/86Sr ~0.70724). The latter is interpreted to represent a new magmatic component that entered the Campi Flegrei caldera feeding system in the past 5ka, the previously recognized Astroni 6 component. However, diopside crystals in Astroni 6 are characterized by even lower 87Sr/86Sr, in the range of 0.7060–0.7068 and by the highest 143Nd/144Nd ratios measured in the products of Astroni activity. These diopsides may represent another common magmatic component, as they have been found in most of the Phlegrean Volcanic District products emplaced over the past 75ka. These diopsides, crystallized in a mantle-derived mafic magma, were entrapped by the Astroni 6 magma during ascent, before it mingled/mixed with the more differentiated and enriched in radiogenic Sr resident magma, thus attaining an intermediate Sr-Nd isotopic fingerprint.These results have an important outcome on the understanding of the volcano behavior, as renewed activity can be triggered by the arrival of fresh magma in the feeding system that would mingle/mix with the resident magma. Such an event may be able to start an unrest phase at the volcano that could last for years or decades, perhaps culminating in a new eruption.

Ten years of satellite observations reveal highly variable sulphur dioxide emissions at Anatahan Volcano, Mariana Islands

AbstractSatellite remote sensing enables continuous multiyear observations of volcanic activity in remote settings. Anatahan (Mariana Islands) is a remote volcano in the western North Pacific. Available ground‐based measurements of sulphur dioxide (SO2) gas emissions at Anatahan place it among thelargest volcanic SO2 sources worldwide. These ground‐based measurements, however, are restricted to eruptive intervals. Anatahan's activity since 2003 has been dominated temporally by prolonged periods of quiescence. Using 10 years of satellite observations from OMI, AIRS, SCIAMACHY, and GOME‐2, we report highly variable SO2 emissions within and between eruptive and quiescent intervals at Anatahan. We find close correspondence between levels of activity reported at the volcano and levels of SO2 emissions detected from space. Eruptive SO2 emission rates have a mean value of ∼6400 t d−1, but frequently are in excess of 20,000 t d−1. Conversely, SO2 emissions during quiescent intervals are below the detection limit of space‐based sensors and therefore are not likely to exceed ∼300 t d−1. We show that while Anatahan occupies a quiescent state for 85% of the past 10 years, only ∼15% of total SO2 emissions over this interval occur during quiescence, with the remaining ∼85% released in short duration but intense syn‐eruptive degassing. We propose that the integration of multiyear satellite data sets and activity histories are a powerful complement to targeted ground‐based campaign measurements in better describing the long‐term degassing behavior of remote volcanoes.

Introduction à l'hydrovolcanologie

Our knowledge of the physics of how volcanoes work has expended enormously over the past 20 years, as have our methods of studying volcanic processes. In seeking to understand volcanic behavior, volcanologists call on a diversity of physics subdisciplines, including fluid dynamics, thermodynamics, solid mechanics, hydrovolcanology, bal‑ listics and acoustics, to name a few. Deep hydrovolcanology describes the water involvement in magma generation and segregation through partial melting into the Earth's crust and/or mantle, magma upward migration in the volcanic plumb‑ ing system and exsolution‑fragmentation in the subsurface. As the magma rises towards the surface the confining pres‑ sure decreases, the volatiles gradually exsolve from the magma forming the gas bubbles which are distributed throughout the liquid. It is the connecting together of a network of these bubbles that ultimately causes the continuous body of liquid to break apart or fragment into a spray of droplets or clots suspended in the gas. In magmas, typically 95‑99% of the 'mass' of material erupted is liquid rock - at most the gas accounts for only a few percent of the weight; but that small amount of gas represents a very large 'volume' as it expands to atmospheric pressure, and is fundamentally impor‑ tant in producing explosive eruptions. Continued rise of the magma leads to further exsolution of gas and growth of gas bubbles through diffusion, decompression and bubble coalescence. The relative importance of each process depends on the amount of volatiles (gas ‑ mostly water) present in the magma, the magma composition and the magma rise speed. Surface hydrovolcanology is involved in pre and post‑eruptive paravolcanic activity such as solfataras, fumaroles, hydro‑ thermal heat and water fluxes. It also focuses on limnic eruptions, otherwise referred to as a lake overturns, a type of natural disaster in which dissolved carbon dioxide (CO 2 ) suddenly erupts from deep volcanic lakes, suffocating wildlife, livestock and humans. Hydrovolcanology presents a new perspective within hydrotechnical sciences where water is a trigger in magma generation and segregation, magma rising and eruption style. Water appears to be a most valuable indicator for volcanic hazard assessment and mitigation, short‑term eruption prediction, and volcanic risk management. Understanding the physical behavior of volcanoes is critical for assessing the hazards posed to the ever‑increasing popu‑ lations living in close proximity to active volcanoes, and thus for mitigating the risk posed by those hazards. Mots‑cles : hydrovolcanology, deep hydrogeology, volcanology, hydrology

Liquid-Phase Catalytic Transfer Hydrogenation of Furfural over Homogeneous Lewis Acid-Ru/C Catalysts.

The catalytic performance of homogeneous Lewis acid catalysts and their interaction with Ru/C catalyst are studied in the catalytic transfer hydrogenation of furfural by using 2-propanol as a solvent and hydrogen donor. We find that Lewis acid catalysts hydrogenate the furfural to furfuryl alcohol, which is then etherified with 2-propanol. The catalytic activity is correlated with an empirical scale of Lewis acid strength and exhibits a volcano behavior. Lanthanides are the most active, with DyCl3 giving complete furfural conversion and a 97 % yield of furfuryl alcohol at 180 °C after 3 h. The combination of Lewis acid and Ru/C catalysts results in synergy for the stronger Lewis acid catalysts, with a significant increase in the furfural conversion and methyl furan yield. Optimum results are obtained by using Ru/C combined with VCl3 , AlCl3 , SnCl4 , YbCl3 , and RuCl3 . Our results indicate that the combination of Lewis acid/metal catalysts is a general strategy for performing tandem reactions in the upgrade of furans.

Great challenges in volcanology: how does the volcano factory work?

INTRODUCTION Scientists are asked to describe and understand the complex behavior of natural processes. This is often done in difficult conditions, with instruments detecting specific indicators and providing limited datasets to satisfy knowledge and imagination. Despite these limitations, many studies have been able to provide unprecedented understanding of different processes in nature, albeit often under specific (i.e., simplified) conditions. A progressively more quantitative approach has been often obtained exploiting the latest technological improvements available. The study of volcanic, or more generally, magmatic processes well exemplifies these conditions and progression (Figure 1). Qualitative reports of how volcanoes erupt date back to thousands of years, as the description of the 79 AD Vesuvio eruption from Pliny the Younger; however, most of our qualitative and quantitative understanding of the volcano factory and its various indicators has been definitely achieved in the frame of the technological boost of the last decades. Certainly, the tremendous improvement of the monitoring system of active and erupting volcanoes has allowed detecting many changes in the geophysical, geodetic and geochemical behavior before, during and after eruptions (e.g., Lowenstern et al., 2006; Sigmundsson et al., 2010; Chiodini et al., 2012). As a result, a significant amount of data has been collected on a reasonable amount of active volcanoes worldwide, and it is in general possible to assign some physical or chemical meaning to many detected changes. This knowledge is also crucial to define when a volcano enters a phase of deviation from its baseline, or unrest, which may culminate in an eruption and to forecast any impending eruption. The understanding of the processes occurring within volcanoes, ultimately leading to the geophysical, geodetic and geochemical changes detected at the surface, is supported by analytical, numerical, and experimental models (e.g., Cayol et al., 2000; Gudmundsson, 2006; Caricchi et al., 2007; Ruch et al., 2012). Modeling has reached a relatively sophisticated stage, allowing understanding otherwise inaccessible and/or long-lasting 2D and, to a lesser extent, 3D processes. Similarly crucial to understand the mean to longerterm behavior of volcanoes are many field and petrological-geochemical studies, supported by dating techniques (e.g., Gravley et al., 2007; Thordarson and Larsen, 2007; Collins et al., 2009; Wilson and Charlier, 2009; Corsaro et al., 2013). In particular, field studies prove fundamental in reconstructing the eruptive history of a volcano, including the eruption location, type, size and frequency; petrological and geochemical studies provide an invaluable amount of information on the processes and times characterizing the formation of the magma, its rise and emplacement within the crust, including mixing, mingling, crustal assimilation, and fractionation. These approaches have allowed reaching a dramatic advancement in our understanding of volcanoes. An overview of the major improvements in volcanology in the last decades is beyond the scope of this contribution. For facts, one can refer to the comprehensive, detailed and essential overview of Cashman and Sparks (2013). This includes many of the important studies on the emplacement (formation of magma chambers), rise (eruption triggers, dike propagation), and eruption of magma (conduit construction and evolution, magma rheology and fragmentation, eruptive styles). The described amount of research underlines the impressive efforts made by the volcanological community in considering and analyzing the several complex evolutionary stages of a magma within the volcano factory, from its generation to its eruption. Even though the reached level of knowledge may not unravel the many questions behind the volcano factory, it certainly provides a robust platform to test hypotheses and plan more advanced and sophisticated studies. Indeed, despite the important achievements, modern volcanology still has to fully define and understand several major processes, involving different topics and approaches, and resulting in likewise challenges for the future. Here the first-order processes, or challenges for volcanology, are summarized in an ideal journey from the deepest to the shallowest portions of the volcano factory (Figure 2). Many of these processes may be unraveled not only by observations on volcanoes on Earth, but also on extraterrestrial volcanoes, including those on Venus, Mars and Io. While studies on terrestrial volcanism provide the key to understand also extraterrestrial volcanism, it is likewise expectable that observations on adequately imaged volcanic edifices from Mars and Venus allow to better define volcanic processes on Earth.

LIPS: Link Prediction as a Service for data aggregation applications

A central component of the design of wireless sensor networks is reliable and efficient transmission of data from source to destination. However, this remains a challenging problem because of the dynamic nature of wireless links, such as interference, diffusion, and path fading. When the link quality gets worse, packets will get lost even with retransmissions and acknowledgments when internal queues become full. For example, in a well-known study to monitor volcano behavior (Werner-Allen et al., 2006), the measured data yield of nodes ranges from 20% to 80%. To address this challenge brought by unreliable links, in this paper, we propose the idea of LIPS, or Link Prediction as a Service. Specifically, we argue that it is beneficial for applications to be aware of link layer variations, so that they can take into account the future link quality estimates based on past measurements. In particular, we present a novel state space based approach for the link quality prediction, and demonstrate that it is possible to integrate this model into operating system interfaces, so that higher layer data aggregation protocols can directly exploit these interfaces to improve their performance. Our intensive evaluation indicates the state space based approach is accurate, stable and lightweight comparing to other strategies such as the autoregressive model (Liu and Cerpa, 2010). We carry out experiments based on the commonly used sensor node hardware including both link layer and operating system measurements.

A sagging-spreading continuum of large volcano structure

Gravitational deformation strongly infl uences the structure and eruptive behavior of large volcanoes. Using scaled analog models, we characterize a range of structural architectures produced by volcano sagging and volcano spreading. These arise from the interplay of variable basement rigidity and volcano-basement (de-)coupling. From comparison to volcanoes on Earth (La Reunion and Hawaii) and Mars (Elysium and Olympus Montes), the models highlight a structural continuum in which large volcanoes throughout the Solar System lie.

Determination of the largest clast sizes of tephra deposits for the characterization of explosive eruptions: a study of the IAVCEI commission on tephra hazard modelling

The distribution of clasts deposited around a volcano during an explosive eruption typically contoured by isopleth maps provides important insights into the associated plume height, wind speed and eruptive style. Nonetheless, a wide range of strategies exists to determine the largest clasts, which can lead to very different results with obvious implications for the characterization of eruptive behaviour of active volcanoes. The IAVCEI Commission on Tephra Hazard Modelling has carried out a dedicated exercise to assess the influence of various strategies on the determination of the largest clasts. Suggestions on the selection of sampling area, collection strategy, choice of clast typologies and clast characterization (i.e. axis measurement and averaging technique) are given, mostly based on a thorough investigation of two outcrops of a Plinian tephra deposit from Cotopaxi volcano (Ecuador) located at different distances from the vent. These include: (1) sampling on a flat paleotopography far from significant slopes to minimize remobilization effects; (2) sampling on specified-horizontal-area sections (with the statistically representative sampling area depending on the outcrop grain size and lithic content); (3) clast characterization based on the geometric mean of its three orthogonal axes with the approximation of the minimum ellipsoid (lithic fragments are better than pumice clasts when present); and (4) use of the method of the 50th percentile of a sample of 20 clasts as the best way to assess the largest clasts. It is also suggested that all data collected for the construction of isopleth maps be made available to the community through the use of a standardized data collection template, to assess the applicability of the new proposed strategy on a large number of deposits and to build a large dataset for the future development and refinement of dispersal models.

Remote sensing of volcanoes and volcanic processes: integrating observation and modelling – introduction

Volcanoes are often remote, and have footprints that may extend across many hundreds or thousands of square kilometres. They are generally inaccessible during eruption, and may continue to be inaccessible for extended periods of time after eruption, while their products can be scattered or dispersed over regional or global scales. Consequently, since direct measurement can only provide us with part of the picture of many volcanic processes, remote sensing is now playing an increasingly important role in advancing understanding of the science underlying volcanic behaviour, on this planet and beyond (e.g. Mouginis-Mark et al. 2000; Sparks et al. 2012). Satellite, airborne and ground-based remote sensing are increasingly vital tools for monitoring active or potentially active volcanoes, and assessing their likely, real-time or time-averaged impact (Fig. 1). At the same time, the synoptic-scale surveys that are often well suited to remote-sensing techniques allow us to address questions about the fundamental processes that control volcano behaviour in a way that is not necessarily possible from individual case studies. New research is often driven by technological advancements in the development of novel sensors or launching of new platforms, meaning that the space agencies are increasingly involved in identifying scientific questions and priorities (e.g. Ferruci et al. 2012). Multiple and complementary data streams are increasingly being used both to monitor active volcanoes and advance volcanological science. The key geophysical parameters that comprise monitoring data streams typically include the categories of (i) seismicity, (ii) surface deformation, (iii) thermal measurements and (iv) gas flux and composition data as major components. While measurements of seismicity remain the domain of ground-based seismometers, remote-sensing techniques have made major contributions in each of the others. This Special Publication volume is concerned with the use of remote sensing at volcanoes. It is split into three parts, roughly arranged from the subsurface, to the surface, and then further afield as volcanic products are injected and dispersed into the atmosphere. The papers span a range of applications of remote-sensing techniques to monitor and understand (a) surface deformation, (b) surface thermal anomalies and (c) gas fluxes, as well as tracking ash and gas plumes from eruptions to gain insights into the extent of a volcano’s impacts. Volcanology is driven, in part, by the operational concerns surrounding volcano monitoring and hazard and crisis management but the goal of volcanological science is, at its heart, to understand the processes that underlie volcanic activity. This Special Publication is also concerned with how we go from observations to this deeper understanding, including the progress that can be made by integrating observations and modelling. While this volume focuses mainly on satellite-based remote sensing, integrating datasets from different platforms is also of vital importance, and so papers on airborne remote sensing and measurement from both manned and unmanned aircraft are also included.