Monitoring Of Active Volcanoes Research Articles

First Implementation of a Normalized Hotspot Index on Himawari-8 and GOES-R Data for the Active Volcanoes Monitoring: Results and Future Developments

The Advanced Himawari Imager (AHI) and Advanced Baseline Imager (ABI), respectively aboard Himawari-8 and GOES-R geostationary satellites, are two important instruments for the near-real time monitoring of active volcanoes in the Eastern Asia/Western Pacific region and the Pacific Ring of Fire. In this work, we use for the first time AHI and ABI data, at 10 min temporal resolution, to assess the behavior of a Normalized Hotspot Index (NHI) in presence of active lava flows/lakes, at Krakatau (Indonesia), Ambrym (Vanuatu) and Kilauea (HI, USA) volcanoes. Results show that the index, which is used operationally to map hot targets through the Multispectral Instrument (MSI) and the Operational Land Imager (OLI), is sensitive to high-temperature features even when short-wave infrared (SWIR) data at 2 km spatial resolution are analyzed. On the other hand, thresholds should be tailored to those data to better discriminate thermal anomalies from the background in daylight conditions. In this context, the multi-temporal analysis of NHI may enable an efficient identification of high-temperature targets without using fixed thresholds. This approach could be exported to SWIR data from the Flexible Combined Imager (FCI) instrument aboard the next Meteosat Third Generation (MTG) satellites.

Exploring the Kinematic Structure of Mount Etna Volcano (Sicily, Italy) by Deformation Analysis and Gravity Gradient Tensors

Ground deformation monitoring of active volcanoes is used routinely to determine phases of vol‐ cano unrest and can provide insights in the evolving plumbing system of a volcano and the influence local tectonics structures have on the volcano tectonic evolution of the volcanic edifice. Volcanic deformation analysis can be performed using velocity and direction measurements of the ground surface using Global Navigation Satellite System (GNSS). In this study, we perform two‐dimen‐ sional deformation analyses of pre‐ and post‐eruptive phases with the scope of determining the strain before and after an eruptive phase at Mt. Etna Volcano (southern Italy) during 2004‐2006. In order to do so, we analyse the GNSS displacement data from Mt. Etna between 2004‐2005 and 2005‐2006 using the dedicated SSPX software. The extention, dilation and rotation maps of the study area were determined. The contraction and volumetric decrease concomitant the 2004‐2005 effusive eruptive period and extension and volumetric increase for the 2005‐2006 data series were observed. The deformation on the northeast part of Mt. Etna Volcano, which showed different characteristics with respect to its surroundings, was thought to be conditioned by the dynamic of the Pernicana fault system. Additionally, Complete Spherical Bouguer (CSB) gravity anomaly and the gravity gradient tensors were calculated giving insight on the subsurface structures of Mt. Etna Volcano and its surroundings.

Real-time analysis of the fine particles in volcanic plumes: A pilot study of Laser Induced Breakdown Spectroscopy with Calibration-Free approach (CF-LIBS)

Volcanic plumes are rich in fine juvenile ash, representing magma fragments expelled from the crater during explosive eruptions. The composition of fine ash is of primary importance for volcano monitoring and hazard assessment, but not much effort has been put until now to build portable instrumentation allowing real-time measurements. In this paper, a laboratory experiment is carried out to build and test an apparatus based on Calibration-Free Laser Induced Breakdown Spectroscopy (CF-LIBS). This methodology is extremely promising because it does not require any standard calibration strategies and the elemental composition is directly obtained by the laser-induced breakdown optical emission. In the experiment, volcanic ash samples are suspended in the air by a laser-induced shockwave in a dedicated chamber, as to mimic the conditions of a volcanic plume, and contemporaneously the laser-induced plasma (LIP) spectrum is analyzed. After spectrum acquisition, the quantitative analysis is performed using the so-called Calibration-Free (CF) analytical method, which is based on the assumption of plasma local thermodynamic equilibrium (LTE). Results show that by such methodology it is possible to measure ash composition in real-time, during its dispersion, with good precision. Based on the result of this experiment, the construction of a portable instrument to be used in the field for the monitoring of active volcanoes could be possible in the future.

A GIS-Based Hydrogeological Approach to the Assessment of the Groundwater Circulation in the Ischia Volcanic Island (Italy)

Assessing the variations in space and time of groundwater circulation in volcanic islands is of paramount importance to the description of the hydro-geo-thermal system and implementation of hydrogeological, geochemical, and volcanic monitoring systems. In fact, the reliable reconstruction of the groundwater potentiometric surface in such composite volcanic aquifer systems can enable the identification of the most advantageous strategies for both the sustainable use of groundwater resources and the management of volcanic risk. Geographical Information System (GIS) platforms can support the integration and analysis of many spatial and temporal variables derived from monitoring of active volcanoes and the elaboration of spatially continuous data. However, open issues still affect the reliability and general applicability of common spatial interpolation methods in the case of groundwater potentiometric surfaces. This is related to the assessment of the main stratigraphic and volcano-tectonic features affecting the hydraulic head changes. With regard to the dynamically very active Ischia Island (Italy), this study illustrates a GIS-based hydrogeological approach to identify the most accurate interpolation method for mapping the potentiometric surface in complex hydrogeological terrains. The proposed approach has been applied to the existing dataset (1977–2003) stored by Istituto Nazionale di Geofisica e Vulcanologia. Based on a careful geological and hydrogeological survey, a total of 267 wells, from 5 to 250 m in depth, were processed. The data pre-processing involved four meteorological time-series data (1922–1997) and six long records of piezometric water levels (1930–1994). As a result, knowledge of the delineation of rather homogeneous stratigraphic and volcano-tectonic structures at the basin-scale has improved. Thus, new, more reliable potentiometric surfaces of the four main geothermal areas closest to the coast were produced during both dry and wet seasons. The reliability of the processed potentiometric surface was then validated by comparing the spatially continuous data with complementary field data. These findings point toward an optimal interpolation approach for representing the seasonal and areal distribution of main hydrogeological parameters in complex aquifer systems. Finally, insights into variations of hydrological behavior at an active volcanic area will foster an understanding of possible involvement of fresh and thermal waters in triggering phreatic explosions.

Volcanic Processes Monitoring and Hazard Assessment Using Integration of Remote Sensing and Ground-Based Techniques

The monitoring of active volcanoes is a complex task based on multidisciplinary and integrated analyses that use ground, drones, and satellite monitoring devices [...]

Detailed Mapping of Lava and Ash Deposits at Indonesian Volcanoes by Means of VHR PlanetScope Change Detection

Mapping of lava flows in unvegetated areas of active volcanoes using optical satellite data is challenging due to spectral similarities of volcanic deposits and the surrounding background. Using very high-resolution PlanetScope data, this study introduces a novel object-oriented classification approach for mapping lava flows in both vegetated and unvegetated areas during several eruptive phases of three Indonesian volcanoes (Karangetang 2018/2019, Agung 2017, Krakatau 2018/2019). For this, change detection analysis based on PlanetScope imagery for mapping loss of vegetation due to volcanic activity (e.g., lava flows) is combined with the analysis of changes in texture and brightness, with hydrological runoff modelling and with analysis of thermal anomalies derived from Sentinel-2 or Landsat-8. Qualitative comparison of the mapped lava flows showed good agreement with multispectral false color time series (Sentinel-2 and Landsat-8). Reports of the Global Volcanism Program support the findings, indicating the developed lava mapping approach produces valuable results for monitoring volcanic hazards. Despite the lack of bands in infrared wavelengths, PlanetScope proves beneficial for the assessment of risk and near-real-time monitoring of active volcanoes due to its high spatial (3 m) and temporal resolution (mapping of all subaerial volcanoes on a daily basis).

Increment in the volcanic unrest and number of eruptions after the 2012 large earthquakes sequence in Central America

Understanding the relationship cause/effect between tectonic earthquakes and volcanic eruptions is a striking topic in Earth Sciences. Volcanoes erupt with variable reaction times as a consequence of the impact of seismic waves (i.e. dynamic stress) and changes in the stress field (i.e. static stress). In 2012, three large (Mw ≥ 7.3) subduction earthquakes struck Central America within a period of 10 weeks; subsequently, some volcanoes in the region erupted a few days after, while others took months or even years to erupt. Here, we show that these three earthquakes contributed to the increase in the number of volcanic eruptions during the 7 years that followed these seismic events. We found that only those volcanoes that were already in a critical state of unrest eventually erupted, which indicates that the earthquakes only prompted the eruptions. Therefore, we recommend the permanent monitoring of active volcanoes to reveal which are more susceptible to culminate into eruption in the aftermath of the next large-magnitude earthquake hits a region.

Monitoring of active volcanoes in Peru by the Instituto Geofísico del Perú

Volcano monitoring in Peru is carried out by the Instituto Geofísico del Perú (IGP), through its Centro Vulcanológico Nacional (CENVUL). CENVUL monitors 12 out of 16 volcanoes considered as historically active and potentially active in southern Peru and issues periodic bulletins about the volcanic activity and, depending on the alert-level of each volcano, also issues alerts and warnings of volcanic unrest, ash dispersion, and the occurrence of lahars. The information generated by CENVUL is disseminated to the civil authorities and the public through different information media (newsletters, e-mail, website, social media, mobile app, etc.). The IGP volcanology team was formed after the eruption of Sabancaya volcano in 1988. Since then, geophysical and geological studies, volcanic hazards assessments, and multidisciplinary monitoring realized by the IGP, have provided a comprehensive understanding of volcanic activity in Peru and forecast future eruptive scenarios. Currently, 80% of the historically active and potentially active volcanoes in Peru are equipped with networks of multiparameter instruments, with the seismic monitoring being the most widely implemented. In this report, we present the situation of volcanic monitoring in Peru, the monitoring networks, the techniques employed, as well as efforts to educate and inform the public and officials responsible for disaster risk management.

Petrological monitoring of active volcanoes: A review of existing procedures to achieve best practices and operative protocols during eruptions

A questionnaire to survey the common petrological monitoring procedures adopted by volcano monitoring institutions has been developed, aimed at identifying prevailing techniques and rating their suitability in terms of costs versus benefits. The collected information resulted from a sample of eighteen participating institutions, which include countries with some of the most important active volcanic provinces worldwide. The participating institutions also offer insights into volcanoes with a variety of volcanic activity, providing a comprehensive picture of the state of art of petrological monitoring. The final purposes are (i) to promote the advancement that petrologic monitoring brings in the comprehension of the eruptive processes, providing the only “signals” (i.e., rock samples) concerning the physico-chemical properties of the magma feeding the eruption; (ii) to design best practices, and (iii) to define the minimum requirements needed to perform an efficient petrological monitoring during ongoing eruptions. The survey also highlighted the main problems to overcome to have a profitable petrological monitoring infrastructure, including (i) the time required to accomplish both field survey and laboratory works (sampling, sample preparation, and analyses), (ii) the lack of onsite analytical facilities, (iii) the shortage of qualified staff.Starting from the state of the art of petrological monitoring, how it is performed by the different institutions worldwide, and what participants considered as the major problems, we identified the Best Practices in Petrological Monitoring as the best compromise between fast and easy analyses and the relevance of the acquired results.

Crustal folds alter local stress fields as demonstrated by magma sheet — Fold interactions in the Central Andes

For magma chambers to form or volcanic eruptions to occur magma must propagate through the crust as dikes, inclined sheets and sills. Most models that investigate magma paths assume the crust to be either homogeneous or horizontally layered, often composed of rocks of contrasting mechanical properties. In regions that have experienced orogenesis, like the Andes, the crust has been deformed over several million years, resulting in rock layers that are commonly folded and steeply dipping. The assumption of homogeneous properties or horizontal layering then does not capture all of the potential magma path-crustal interactions. Here we tackle this problem by determining the effect of a crust made of steeply inclined layers in which sills and inclined sheets are emplaced. We combine field observations from a sill emplaced in the core of an anticlinal fold at El Juncal in the Chilean Central Andes, including lithologies, sill and fold limbs attitude, length and thickness with a suite of finite element method models to explore the mechanical interactions between inclined layers and magma paths. Our results demonstrate that the properties of the host rock layers as well as the contacts between the layers and the geometry of crustal structures all play an important role in magma propagation and emplacement at shallow levels. Sill propagation and emplacement in heterogeneous and anisotropic crustal segments change the crustal stress field promoting sill arrest, deflection or further propagation. Specifically, sills are more likely to be deflected when encountering shallow dipping layers rather than steeply dipping layers of a fold. Mechanically weak contacts encourage sill deflection due to the related rotation of the stress field and this effect is attenuated when the folded layers are steeper. These processes may change the amount and style of recorded surface deformation, with implications for monitoring of active volcanoes.

Onset and evolution of Kīlauea's 2018 flank eruption and summit collapse from continuous gravity

Prior to the 2018 lower East Rift Zone (ERZ) eruption and summit collapse of Kīlauea Volcano, Hawai‘i, continuous gravimeters operated on the vent rims of ongoing eruptions at both the summit and Pu‘u ‘Ō‘ō. These instruments captured the onset of the 2018 lower ERZ eruption and the effects of lava withdrawal from both locales, providing constraints on the timing and style of activity and the physical properties of the lava lakes at both locations. At the summit, combining gravity, lava level, and a three-dimensional model of the vent indicates that the upper ∼200 m of the lava lake had a density of about 1700 kgm−3, slightly greater than estimates from 2011–2015 and possibly indicating a gradual densification over time. At Pu‘u ‘Ō‘ō, gravity and vent geometry were used to model both the density and the rate of crater collapse, which was unknown owing to a lack of visual observations. Results suggest the withdrawal of at least 11×106 m3 of lava over the course of two hours, and a material density of 1800–1900 kgm−3. In addition, gravity data at Pu‘u ‘Ō‘ō captured a transient decrease and increase about an hour prior to crater collapse and that was probably related to a small, short-lived fissure eruption on the west flank of the cone and possibly to dike intrusion beneath Pu‘u ‘Ō‘ō. The fissure was the first event in the subsequent cascade that ultimately led to the extrusion of over 1 km3 of lava from lower ERZ vents, collapse of the summit caldera floor by more than 500 m, and the destruction of over 700 homes and other structures. These results emphasize the importance of continuous gravity in operational monitoring of active volcanoes.

Application of Subspace-Based Detection Algorithm to Infrasound Signals in Volcanic Areas

Infrasonic signals investigation plays a fundamental role for both volcano monitoring purpose and the study of the explosion dynamics. Proper and reliable detection of weak signals is a critical issue in active volcano monitoring. In particular, in volcanic acoustics, it has direct consequences in pinpointing the real number of generated events (amplitude transients), especially when they exhibit low amplitude, are close in time to each other, and/or multiple sources exist. To accomplish this task, several algorithms have been proposed in literature; in particular, to overcome limitations of classical approaches such as short-time average/long-time average and cross-correlation detector, in this paper a subspace-based detection technique has been implemented. Results obtained by applying subspace detector on real infrasound data highlight that this method allows sensitive detection of lower energy events. This method is based on a projection of a sliding window of signal buffer onto a signal subspace that spans a collection of reference signals, representing similar waveforms from a particular infrasound source. A critical point is related to subspace design. Here, an empirical procedure has been applied to build the signal subspace from a set of reference waveforms (templates). In addition, in order to determine detectors parameters, such as subspace dimension and detection threshold, even in presence of overlapped noise such as infrasonic tremor, a statistical analysis of noise has been carried out. Finally, the subspace detector reliability and performance, have been assessed by performing a comparison among subspace approach, cross-correlation detector and short-time average/long-time average detector. The obtained confusion matrix and extrapolated performance indices have demonstrated the potentiality, the advantages and drawbacks of the subspace method in tracking volcanic activity producing infrasound events. This method revealed to be a good compromise in detecting low-energy and very close in time events recorded during Strombolian activity.

Induced polarization of volcanic rocks. 4. Large-scale induced polarization imaging

SUMMARY Thanks to the emergence of new technologies developed with the goal of performing large-scale galvanometric induced polarization surveys and thanks a better understanding of the underlying physics of induced polarization, this geophysical method can now be applied in the field of volcanology and geothermal resources assessment. A new approach is developed here for directly inverting the primary and secondary electric fields recorded at a set of independent stations when injecting a primary current. The use of independent stations to measure the primary and secondary electrical fields improves the quality of the data by reducing the capacitive coupling effects inherent to systems based on long cables. It avoids issues associated with using the same electrodes for both current injection and voltage measurements and negative apparent resistivity and chargeability values. With such acquisitions, we can perform true 3-D surveys in areas characterized by complex topography such as volcanoes. The numerical scheme we developed returns as output the electrical conductivity and chargeability fields. The implemented methodology presents several advantages. The first is the use of data types at the stations, for example the electric field intensity, that are independent from the local geometrical station parameters such as electrode spacing and dipole orientation. The second advantage lies in the suitability of the proposed approach to perform large-scale applications since we use a matrix-free approach that does not require the assembly of the Jacobian matrices. The third concerns the possibility of performing the inversion on complex geometries through a consistent use of the finite element method on unstructured meshes in combination with algebraic multigrid preconditioning for the regularization and the solution of the forward and adjoint problems. The computation of 3-D sensitivity maps can also be a real asset in survey design. After validating our approach with a benchmark synthetic case study, we test it on a large-scale induced polarization survey that mimic true field conditions on a volcanic environment with rough topography. Our tests demonstrate the high potential of this electric field approach in volcanology especially for deep (3 km) imagining of the internal structure of volcanoes, which in turn could improve our understanding of hydrothermal systems and allow the monitoring of active volcanoes and the potential risk of collapse.

Development and status of active volcano monitoring in China

Abstract Following decades of geological surveys and studies, 14 active volcanic fields have been identified in China. Evidence for Holocene volcanism in several of these areas highlights the need to understand and monitor volcanic hazards in those regions. Six volcano observatories have thus been established in the past 40 years. This work reviews China's national capability and history of volcano monitoring, with emphasis on the Changbaishan–Tianchi Volcano Observatory and the Tengchong Volcano Observatory. The Changbaishan–Tianchi Volcano Observatory (CTVO) was constructed in 1996 and began monitoring in 1999, with limited recorded observations dating back to 1973. Currently, CTVO is the largest and most advanced observatories in China. The monitoring network of the CTVO incorporates 11 seismic and 15 GPS stations, two levelling routes and three gas geochemistry sampling points. The Changbaishan–Tianchi Volcano experienced unrest during 2002–05, evidenced in elevated levels of seismicity and ground deformation, as well as shifts in gas geochemistry. After 2006, the volcano returned to quiescence, with activities at background levels as recorded in 1973–2001. The monitoring network of Tengchong Volcano Observatory incorporates eight seismic stations, 20 GPS points, 95 levelling points and three gas geochemistry sampling points. The observations made since 1965 indicate significant seismicity, with more than 3000 events recorded in 2011, mostly related to regional tectonics. Tengchong is known for its widespread hot springs, with temperatures up to 105°C recorded at Dagunguo spring. The four other observatories are Longgang Volcano Observatory, Jingbohu Volcano Observatory, Wudalianchi Volcano Observatory and Qiongbei Volcano Observatory. They are equipped with seismic, geodetic and geochemical monitoring equipment. These areas saw only low levels of activity over the past several decades, but related fault systems are relatively active. In a relatively short time, China has gained considerable experience in observatory design and volcano monitoring and has trained up a sizeable task force, laying the foundation for sustained volcano monitoring at the national level. Future efforts must focus on maintaining and expanding observational capacity, as well as gaining better dynamic understanding to inform volcano hazard assessment.

Operational Response to Volcanic Ash Risks Using HOTVOLC Satellite-Based System and MOCAGE-Accident Model at the Toulouse VAAC

In 2010, the Eyjafjallajökull volcano erupted, generating an ash cloud causing unprecedented disruption of European airspace. Despite an exceptional situation, both the London and Toulouse Volcanic Ash Advisory Centres (VAAC) provided critical information on the location of the cloud and on the concentration of ash, thus contributing to the crisis management. Since then, substantial efforts have been carried out by the scientific community in order to improve remote sensing techniques and numerical modeling. Satellite instruments have proven to be particularly relevant for the characterization of ash cloud properties and a great help in the operational management of volcanic risk. In this study, we present the satellite-based system HOTVOLC developed at the Observatoire de Physique du Globe de Clermont-Ferrand (OPGC) using Meteosat geostationary satellite and designed for real-time monitoring of active volcanoes. After a brief presentation of the system we provide details on newly developed satellite products dedicated to the ash cloud characterization. This includes, in particular, ash cloud altitude and vertical column densities (VCD). Then, from the Stromboli 2018 paroxysm, we show how HOTVOLC can be used in a timely manner to assist the Toulouse VAAC in the operational management of the eruptive crisis. In the second part of the study, we provide parametric tests of the MOCAGE-Accident model run by the Toulouse VAAC from the April 17 Eyjafjallajökull eruption. For this purpose, we tested a range of eruption source parameters including the Total Grain Size Distribution (TGSD), the eruptive column profile, the top plume height and mass eruption rate (MER), as well as the fine ash partitioning. Finally, we make a comparison on this case study between HOTVOLC and MOCAGE-Accident VCD.

From Sensor to Cloud: An IoT Network of Radon Outdoor Probes to Monitor Active Volcanoes.

While radon in soil gases has been identified for decades as a potential precursor of volcanic eruptions, there has been a recent interest for monitoring radon in air on active volcanoes. We present here the first network of outdoor air radon sensors that was installed successfully on Mt. Etna volcano, Sicily, Italy in September 2019. Small radon sensors designed for workers and home dosimetry were tropicalized in order to be operated continuously in harsh volcanic conditions with an autonomy of several months. Two stations have been installed on the south flank of the volcano at ~3000 m of elevation. A private network has been deployed in order to transfer the measurements from the stations directly to a server located in France, using a low-power wide-area transmission technology from Internet of Things (IoT) called LoRaWAN. Data finally feed a data lake, allowing flexibility in data management and sharing. A first analysis of the radon datasets confirms previous observations, while adding temporal information never accessed before. The observed performances confirm IoT solutions are very adapted to active volcano monitoring in terms of range, autonomy, and data loss.

The Contribution of Multi-Sensor Infrared Satellite Observations to Monitor Mt. Etna (Italy) Activity during May to August 2016

In May 2016, three powerful paroxysmal events, mild Strombolian activity, and lava emissions took place at the summit crater area of Mt. Etna (Sicily, Italy). During, and immediately after the eruption, part of the North-East crater (NEC) collapsed, while extensive subsidence affected the Voragine crater (VOR). Since the end of the May eruptions, a diffuse fumarolic activity occurred from a fracture system that cuts the entire summit area. Starting from 7 August, a small vent (of ~20–30 m in diameter) opened up within the VOR crater, emitting high-temperature gases and producing volcanic glow which was visible at night. We investigated those volcanic phenomena from space, exploiting the information provided by the satellite-based system developed at the Institute of Methodologies for Environmental Analysis (IMAA), which monitors Italian volcanoes in near-real time by means of the RSTVOLC (Robust Satellite Techniques–volcanoes) algorithm. Results, achieved integrating Advanced Very High Resolution Radiometer (AVHRR) and Moderate Resolution Imaging Spectroradiometer (MODIS) observations, showed that, despite some issues (e.g., in some cases, clouds masking the underlying hot surfaces), RSTVOLC provided additional information regarding Mt. Etna activity. In particular, results indicated that the Strombolian eruption of 21 May lasted longer than reported by field observations or that a short-lived event occurred in the late afternoon of the same day. Moreover, the outcomes of this study showed that the intensity of fumarolic emissions changed before 7 August, as a possible preparatory phase of the hot degassing activity occurring at VOR. In particular, the radiant flux retrieved from MODIS data decreased from 30 MW on 4 July to an average value of about 7.5 MW in the following weeks, increasing up to 18 MW a few days before the opening of a new degassing vent. These outcomes, in accordance with information provided by Sentinel-2 MSI (Multispectral Instrument) and Landsat 8-OLI (Operational Land Imager) data, confirm that satellite observations may also contribute greatly to the monitoring of active volcanoes in areas where efficient traditional surveillance systems exist.

MWPC-based Muographic Observation System for remote monitoring of active volcanoes

Abstract Multi-wire proportional chamber (MWPC) based trackers with exceptional operational stability, high efficiency ( > 95 % ) and low power consumption ( 10 W) are applied to the Muographic Observation System (MOS). Since February 2018, the modular MWPC-based MOS (MMOS) is under operation with three trackers with the total sensitive surface of 2 m2 at the Sakurajima volcano in Kyushu, Japan. The structure and operation of MMOS with its performance is reported and its applicability as a remote volcano monitoring system is discussed.

Initial processing of volcanic seismic signals using Hidden Markov Models: Nevado del Huila, Colombia

Volcanic eruptions are commonly preceded by seismic signals that carry important information about the underlying physical processes driving the eruptive activity. The manual classification of this seismicity is often difficult during seismic crises and timely responses in volcanic surveillance depend upon on how fast this work is performed. Automatic classification programs are an excellent alternative because they can classify seismic signals in near real-time. Although these programs have been successfully tested for many volcanoes, they have not yet been applied to the monitoring of volcanic crises. We automated the initial processing of the seismic activity recorded at Nevado del Huila volcano in Colombia, using Hidden Markov Models. The technique consists of classifying seismic signals, extracting the main characteristics of each classified signal, and deriving important physical parameters that are important in volcanic surveillance. Continuous seismic data from 2007 to 2012 were used to develop this project. A total of 2142 events were selected to train the program. The best characteristic model obtained during the training had an accuracy of 91.25%, and a similar pattern in volcanic behavior to that from manual classification was modeled. The encouraging results demonstrate that automatic classification programs are a powerful tool that can be used in surveillance and monitoring of active volcanoes as they provide timely information for the proper management of volcanic crises and subsequent hazards mitigation.

A review of laboratory and numerical modelling in volcanology

Abstract. Modelling has been used in the study of volcanic systems for more than 100 years, building upon the approach first applied by Sir James Hall in 1815. Informed by observations of volcanological phenomena in nature, including eye-witness accounts of eruptions, geophysical or geodetic monitoring of active volcanoes, and geological analysis of ancient deposits, laboratory and numerical models have been used to describe and quantify volcanic and magmatic processes that span orders of magnitudes of time and space. We review the use of laboratory and numerical modelling in volcanological research, focussing on sub-surface and eruptive processes including the accretion and evolution of magma chambers, the propagation of sheet intrusions, the development of volcanic flows (lava flows, pyroclastic density currents, and lahars), volcanic plume formation, and ash dispersal. When first introduced into volcanology, laboratory experiments and numerical simulations marked a transition in approach from broadly qualitative to increasingly quantitative research. These methods are now widely used in volcanology to describe the physical and chemical behaviours that govern volcanic and magmatic systems. Creating simplified models of highly dynamical systems enables volcanologists to simulate and potentially predict the nature and impact of future eruptions. These tools have provided significant insights into many aspects of the volcanic plumbing system and eruptive processes. The largest scientific advances in volcanology have come from a multidisciplinary approach, applying developments in diverse fields such as engineering and computer science to study magmatic and volcanic phenomena. A global effort in the integration of laboratory and numerical volcano modelling is now required to tackle key problems in volcanology and points towards the importance of benchmarking exercises and the need for protocols to be developed so that models are routinely tested against real world data.