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The eruption of the unique Taketomi side volcano, located on Atlasov Island in the northern part of the Kuril Island arc, began underwater and ended on land. It happened before people's eyes and was, in essence, the formation of a new side volcano. The volcano that formed was studied in 1933–1936 by renowned Japanese scientists, and from 1946 to the present, by Soviet and Russian researchers. The Taketomi side volcano continues to amaze with its landscapes and is actively visited by numerous tourists. Unfortunately, there is still no single publication about people who, to one degree or another, have made a significant contribution to the study of this side volcano. This study is the first attempt to talk about them in lapidary form. In addition, available photographs show the destruction of the Taketomi structure starting in the 1950s until 2020, and for the first time, the existing inconsistencies cited in various publications that describe the eruption of this side volcano are noted. [ABSTRACT FROM AUTHOR]

Today, volcanic sulfur emissions into the atmosphere are measured spectroscopically from the ground, air and space. For eruptions prior to the satellite era, two main sulfur proxies are used, the rock and ice core records, as illustrated by Peccia et al. (2023, https://doi.org/10.1029/2023gl103334). The first approach is based on calculations of the sulfur content of the magma, while the second uses traces of sulfur deposited in ice. Both approaches have their limitations. For glaciochemistry, the volcano responsible for a sulfur anomaly is often unknown and the atmospheric pathway by which the sulfur reached the ice uncertain. The petrologic method relies, too, on uncertain estimates of eruption size and a number of geochemical assumptions that are hard to verify. A deeper knowledge of processes occurring both within magma bodies prior to eruption, and within volcanic plumes in the atmosphere is needed to further our understanding of the impacts of volcanism on climate. Plain Language Summary: Volcanic emissions of sulfur gases during large eruptions can change the global climate. Today, advanced spectroscopic tools allow us to measure sulfur from the ground, air and space. But to understand the impacts of volcanic activity on climate back through history we need to estimate volcanic sulfur releases in other ways. Clues can be found in the pumice deposits found around a volcano and, perhaps more surprisingly, in the ice caps of the polar regions, which receive the eventual fallout from large eruptions. Both approaches have limitations that are addressed in a recent work by Peccia et al. (2023, https://doi.org/10.1029/2023gl103334) and that are at the focus of our commentary. Key Points: The impact of volcanic activity on climate remains difficult to quantify for eruptions prior to the instrumental eraThe petrological and glaciochemical methods each provide answers, but are still fraught with large uncertaintiesWe need to further our understanding of the physicochemical processes occurring both within magma reservoirs and volcanic plumes [ABSTRACT FROM AUTHOR]

Abstract Today, volcanic sulfur emissions into the atmosphere are measured spectroscopically from the ground, air and space. For eruptions prior to the satellite era, two main sulfur proxies are used, the rock and ice core records, as illustrated by Peccia et al. (2023, https://doi.org/10.1029/2023gl103334). The first approach is based on calculations of the sulfur content of the magma, while the second uses traces of sulfur deposited in ice. Both approaches have their limitations. For glaciochemistry, the volcano responsible for a sulfur anomaly is often unknown and the atmospheric pathway by which the sulfur reached the ice uncertain. The petrologic method relies, too, on uncertain estimates of eruption size and a number of geochemical assumptions that are hard to verify. A deeper knowledge of processes occurring both within magma bodies prior to eruption, and within volcanic plumes in the atmosphere is needed to further our understanding of the impacts of volcanism on climate.

Very Long Period (VLP) signals with periods longer than 2 s may occur during eruptive or quiet phases at volcanoes of all types (shield and stratovolcanoes with calderas, as well as other stratovolcanoes) and are inherently connected to fluid movement within the plumbing system. This is supported by observations at several volcanoes that indicate a correlation between gas emissions and VLPs, as well as deformation episodes due to melt accumulation and migration that are followed by the occurrence of VLPs. Moment tensors of VLPs are usually characterized by large volumetric components of either positive or negative sign along with possibly the presence of single forces that may result from the exchange of linear momentum between the seismic source and the Earth. VLPs may occur during a variety of volcanological processes such as caldera collapse, phreatic eruptions, vulcanian eruptions, strombolian activity, and rockfalls at lava lakes. Physical mechanisms that can generate VLPs include the inflation and deflation of magma chambers and cracks, the movement of gas slugs through conduits, and the restoration of gravitational equilibrium in the plumbing system after explosive degassing or rockfalls in lava lakes. Our understanding of VLPs is expected to greatly improve in the future by the use of new instrumentation, such as Distributed Acoustic Sensing, that will provide a much denser temporal and spatial sampling of the seismic wavefield. This vast quantity of data will then require time efficient and objective processing that can be achieved through the use of machine learning algorithms. [ABSTRACT FROM AUTHOR]

There are currently no quantitative short-term eruption forecasts based on peer-reviewed and validated models that are operational for New Zealand's volcanoes. Specific forecasts produced for work-risk assessments are not generally publicised. During a volcanic crisis, eruption forecasts are demanded under high stress and time-restricted conditions. Many forecasting options exist but none are proven as universally viable, with testing and calibration limited to the hindcasting of specific events. Here, we compare the requirements of six methods with currently available data and monitoring capabilities at each of New Zealand's volcanoes to determine which methods are currently feasible, as well as those options that may be implemented with additional effort or equipment. In New Zealand, the major limiting factor in method selection is the low number of past instrumentally monitored eruptions. This data gap may be filled by carefully selected analogue data from a global volcano set and expert knowledge. Event trees and the failure forecasting method may be set up at most volcanoes with minimal effort, but the latter can only forecast eruption onset time. Expert interpretation is the only method available in New Zealand for any forecast output type. [ABSTRACT FROM AUTHOR]

Shallow magma transfer is difficult to detect at poorly monitored volcanoes. Magma transfer before the last 1538 eruption at Campi Flegrei caldera (Italy) was exceptionally tracked using historical, archeological, and geological data. Here, we extend that data set to 1650 to uncover any magma transfer during post‐eruptive subsidence. Results show two post‐eruptive subsidence phases, separated by a previously undocumented uplift during 1540–1582. Uplift highlights the pressurization of the central (∼3.5 km depth) and peripheral (∼1 km depth) pre‐eruptive sources, suggesting an aborted eruption. The subsidence events mainly require the depressurization of the central source and pressurization of a deeper magmatic layer (∼8 km depth). Therefore, despite the overall post‐eruptive deflation, after 1538 the deeper reservoir experienced continuous magma supply, with magma almost erupting between 1540 and 1582, challenging the common assumption of post‐eruptive deflation. This underlies the importance of monitoring the deeper magmatic systems, also after eruptions, to properly assess their eruptive potential. Plain Language Summary: Today, volcanic activity is monitored by satellite and ground networks. However, very little is known about the pre‐ and post‐eruptive behavior of volcanoes before the instrumental era. Here, we present a unique set of archeological records related to the elevation changes at Campi Flegrei caldera (Italy) during 1515–1650, mainly focusing on its behavior after the last 1538 eruption at Monte Nuovo. After the eruption, subsidence occurred from 1538 to 1540, followed, from 1540 to 1582, by a previously unreported uplift; the latter was followed by renewed subsidence until 1650 at least. Modeling the sources responsible for the deformation, we find that, despite the depressurization of shallow sources, after 1538, a deeper magmatic layer (∼8 km depth) experienced continuous magma supply, with magma almost erupting between 1540 and 1582. This questions the common notion of post‐1538 deflation at Campi Flegrei, where the depressurization of the shallower sources masks the pressurization of the deeper magmatic system for more than a century. Key Points: 20 archeological sites at Campi Flegrei show two post‐1538 eruption subsidence phases, separated by an undocumented uplift in 1540–1582During 1540–1582, a central sill‐like source (∼3.5 km depth) transfers magma below Monte Nuovo, representing an aborted eruptionFrom 1538 to 1650 a deeper magmatic layer (∼8 km depth) experienced continuous magma supply, also during caldera subsidence [ABSTRACT FROM AUTHOR]

The eruption activity of Shinmoedake in the Kirishima volcanic group of Japan resumed in 2017–18, following a quiet period during 2011–17. Subplinian eruptions preceded lava effusion in 2011; however, no subplinian eruption occurred during 2017–18. Petrological studies and melt inclusion analyses were conducted to investigate the ascent and degassing of the magma to understand the cause of the different eruption styles. Chemical analysis of the melt inclusions from the 2011 eruption indicates that mafic magma with high volatile content (6.2 wt% H2O, 0.25–1.4 wt% CO2) ascended into the shallow felsic magma (1.9–3.7 wt% H2O, 0.025–0.048 wt% CO2) at depths of 5–6 km. Calculations indicate that the mafic magmas were of lower density (1717–1835 kg m−3) than the felsic magma (2264–2496 kg m−3) at 125 MPa and that the two magmas were mixed. The 2011 mixed magma with high volatile content (4.0 wt% H2O, 0.14–0.70 wt% CO2) had a bubble volume of approximately 50 vol% at 50 MPa, which is likely to have caused the subplinian eruption. The whole-rock and chemical compositions of the plagioclase, clinopyroxene, and orthopyroxene phenocryst cores from 2018 and 2011 were similar, suggesting that the 2018 magma was a remnant of the 2011 magma. Chemical analyses of the groundmass from 2018 and the MELTS calculation indicate that the magma approached chemical equilibrium during 2011–18. Melt inclusion analyses and volcanic gas observation noted a lower bulk volatile content in the 2018 magma (2.1–3.0 wt% H2O, 0.087–0.10 wt% CO2) than that in the 2011 magma. Comparison of the degassed-magma volumes estimated from the S and Cl contents of the melt inclusions, SO2 flux and volcanic gas composition, and erupted-magma volume indicates that excess degassing has been occurring in the magma due to convection since February 2011, which may have decreased the volatile content of the magma. The relatively low volatile content meant that the 2018 magma could not erupt explosively and lava was instead erupted via effusion. [ABSTRACT FROM AUTHOR]

In recent decades Bezymianny Volcano, Kamchatka, one of the most threatening volcanic objects of Russia, has produced an average of 1–2 short-lived, but strong, explosive–effusive eruptions per year. The most reliable source of data for identifying a precursory situation before such an eruption seems to be seismicity, with continuous data being supplied by the Kamchatka seismicity monitoring system. The formalized method developed by the present author for predicting Bezymianny eruptions based on a statistical estimation of seismicity level (SESL'09) has performed satisfactorily in real time as well, with the precursory processes before all the eight eruptions of Bezymianny in 2015–2020 being detected. Revision of all characteristics the method involves (efficiency, reliability, and validity) showed that they remained stable when new data were added. The prediction method was supplemented with a new parameter, lead time, which provides a formal procedure to estimate the expectation time for a prediction to come true. [ABSTRACT FROM AUTHOR]

The forecast of the start date of the Etna volcano eruption is considered. For the first time in the history of volcanology, the forecast was made by two independent methods. The first method analyzed the nature of changes in electromagnetic emission in the environment surrounding the volcano, while the second method predicted the date of Etna's eruption based on a trend composed of regularly measured electromagnetic emission parameters. [ABSTRACT FROM AUTHOR]

This paper discusses the data of instrumental observations conducted at the Mikhnevo Observatory, at INTERMAGNET observatories, and at the Geophysical Monitoring Center of the Institute of Geosphere Dynamics (IGD), Russian Academy of Sciences (RAS) during the explosive eruption of Hunga Tonga-Hunga Ha'apai Volcano of January 15, 2022. It is shown that the explosion of the volcano produced a series of wave disturbances in the atmosphere, as well as electrical and magnetic variations at large epicentral distances. The atmospheric disturbances were recorded as Lamb waves emitted by a source at the center of the explosion, as well as by a virtual source situated at the antipode. The latter source was formed by convergence and summing of signals propagating on the terrestrial sphere. In addition to primary waves, the recorded phenomena also include secondary and tertiary waves due to multiple passage of the explosion-produced signal around the terrestrial sphere. We evaluated the source energy based on the characteristic frequency in the spectrum of the signal, resulting in the value ~1018 J, which corresponds to ~200 MT of TNT, when converted to an explosive source. It is shown that a volcanic explosion is accompanied by electrical and magnetic variations both at the time of the explosion and at the time when the recording site receives atmospheric wave disturbances. [ABSTRACT FROM AUTHOR]

This paper reviews the results of fundamental importance achieved by the Institute of Volcanology and Seismology (IV&S), Far East Branch (FEB), Russian Academy of Sciences (RAS) for the period 1962‒2021. We consider the most important achievements classified under the following headings: Volcanological research includes petrologic and geochemical features of ejecta by volcanoes in the Kuril–Kamchatka region; the age of volcanoes and the phases of volcanogenic catastrophism in Kamchatka; hydrothermal systems and geothermal reserves of Kamchatka; hydrothermal metasomatism and volcanogenic mineral generation and mineralization; Geophysical research includes the seismology of volcanoes; deformation at active volcanoes; tectonic earthquakes and tsunamis; the internal structure of volcanic systems. [ABSTRACT FROM AUTHOR]

The performance of a multi-channel seismometer system with phase-shifted optical interferometry was improved by newly introduced sensors and a processing unit. The current version of the system consists of three optical wired seismometers and the unit. We deployed the system at Sakurajima Volcano and successfully operated it from June to December 2019. As the Sakurajima Volcano frequently erupts, a number of eruption events were observed during the observation period, as were a number of lightning strikes. In this study, we evaluated the observation performance of the volcanic earthquake and the noise caused by the lightning, using the spectrum and amplitude of the waveform. The results show that this sensor can observe earthquakes caused by eruptions as well as ordinary seismometers do. When the lightning struck, pulsed noise with power in a wide frequency band was observed in the existing seismometer, but not in the new sensor. Therefore, the observation was not affected by lightning. In addition, this system was found to be effective in the array analysis of volcanic earthquakes. [ABSTRACT FROM AUTHOR]

The Island of Hawai'i was formed by repeated eruptions of basalts at an oceanic hotspot. Kı̄lauea, the youngest among the subaerial volcanoes of the island, erupted intensely in 2018. The eruption provided an opportunity to look into the mechanisms that operate at the volcano and associated earthquake activities, as it was recorded simultaneously, for the first time, by onshore and offshore seismometers. We used most of the publicly available seismic data during the eruption period, including temporary arrays, to build a more complete earthquake catalog during the eruption than that provided by the Hawaiian Volcano Observatory. We used a short‐time‐average/long‐time‐average method to identify potential earthquakes. The detections were associated with events and automatically picked with P‐wave and S‐wave arrivals, which were used to locate the events in a three‐dimensional velocity model. After re‐examining these earthquake events, their coda/duration magnitudes were determined. The resulting half‐year catalog contains 375,736 events with one of the highest daily earthquake numbers ever reported (6,128 on 21 June 2018). A great number of events were recorded during the caldera collapses, from its beginning until its rapid ending. The catalog also contains abundant events near the Pu'u'ō'ō vent and in the lower East Rift Zone, where an increase of seismicity in mid‐July and August indicated a step‐up in magma intrusion after the eruption. Key Points: Using most available data onshore and offshore, we developed a workflow to detect and locate earthquakes during the 2018 Kı̄lauea eruptionThe new catalog contains a total of 375,736 earthquakes between 1 March and 30 September 2018, 439% more than reported by the Hawaiian Volcano ObservatoryThe new catalog provides a foundational data set, revealing rich information to better understand the eruption processes [ABSTRACT FROM AUTHOR]

The early post-eruptive activity is described on the Third Cone, one of the New Tolbachik volcanoes, formed during the eruption at the Northern Breakthrough during the Great Tolbachik Fissure Eruption, which occurred in Kamchatka in 1975–1976. Changes in temperature, exhalation mineral generation, and rock alteration in the fumarole areas of the northern and southern craters of the Third Cone are characterized. [ABSTRACT FROM AUTHOR]

The volcanic eruption of Cumbre Vieja (La Palma Island, Spain), started on 19 September 2021 and was declared terminated on 25 December 2021. A complete set of aerosol measurements were deployed around the volcano within the first month of the eruptive activity. This paper describes the results of the observations made at Tazacorte on the west bank of the island where a polarized micro-pulse lidar was deployed. The analyzed two-and-a-half months (16 October–31 December) reveal that the peak height of the lowermost and strongest volcanic plume did not exceed 3 km (the mean of the hourly values is 1.43 ± 0.45 km over the whole period) and was highly variable. The peak height of the lowermost volcanic plume steadily increased until week 11 after the eruption started (and 3 weeks before its end) and started decreasing afterward. The ash mass concentration was assessed with a method based on the polarization capability of the instrument. Two days with a high ash load were selected: The ash backscatter coefficient, aerosol optical depth, and the volume and particle depolarization ratios were, respectively, 3.6 (2.4) Mm−1sr−1, 0.52 (0.19), 0.13 (0.07) and 0.23 (0.13) on 18 October (15 November). Considering the limitation of current remote sensing techniques to detect large-to-giant particles, the ash mass concentration on the day with the highest ash load (18 October) was estimated to have peaked in the range of 800–3200 μg m−3 in the lowermost layer below 2.5 km. [ABSTRACT FROM AUTHOR]

Ruapehu (150 km3 cone, 150 km3 ring-plain) and Tongariro (90 km3 cone, 60 km3 ring-plain) are iconic stratovolcanoes, formed since ∼230 and ∼350 ka, respectively, in the southern Taupo Volcanic Zone and Taupo Rift. These volcanoes rest on Mesozoic metasedimentary basement with local intervening Miocene sediments. Both volcanoes have complex growth histories, closely linked to the presence or absence of glacial ice that controlled the distribution and preservation of lavas. Ruapehu cone-building vents are focused into a short NNE-separated pair, whereas Tongariro vents are more widely distributed along that trend, the differences reflecting local rifting rates and faulting intensities. Both volcanoes have erupted basaltic andesite to dacite (53–66 wt.% silica), but mostly plagioclase-two pyroxene andesites from storage zones at 5–10 km depth. Erupted compositions contain evidence for magma mixing and interaction with basement rocks. Each volcano has an independent magmatic system and a growth history related to long-term (>104 years) cycles of mantle-derived magma supply, unrelated to glacial/interglacial cycles. Historic eruptions at both volcanoes are compositionally diverse, reflecting small, dispersed magma sources. Both volcanoes often show signs of volcanic unrest and have erupted with a wide range of styles and associated hazards, most recently in 2007 (Ruapehu) and 2012 (Tongariro). [ABSTRACT FROM AUTHOR]

The spatiotemporal distribution of volcanic activity poses a significant challenge to risk mitigation measures, as it is still largely unexplored in most of the volcanic systems. In this study, we re-assess the deformation observed by leveling surveys covering the nationwide tragedy 1963–1965 Irazú eruption in Costa Rica with a state-of-the-art analytical source inversion model. We combine the analytical model results with recent geophysical, geochemical, and petrology data to build a geological model of Irazú and its 10 km-distant Turrialba volcano. Based on the leveling survey, the source inversion model finds a reservoir between 5 and 7 km below the Irazú crater which is deeper than previously published. We also confirm that the source location is on top of the mid-crustal reservoir that was feeding Turrialba between the 2010–2022 eruptions. Using previous seismic tomography, gravity, petrology, and geochemistry study of Turrialba and Irazú, as well as other studies conducted on nearby volcanoes worldwide, we find that Irazú and Turrialba volcanoes likely share a mid-crustal plumbing system which could suggesting that their plumbing systems are interconnected with each other. These findings have important implications on the spatiotemporal distribution of the volcanic activity and for the 2.8 million inhabitants settled within a 50 km radius. Observations during recent episodes indicates that inflation beneath Irazú has the potential to trigger eruptive activity at either Irazú or Turrialba. While further analysis is required to assess the tectonic control on volcanic activity, tectonic processes may shape both short- and long-term volcanic activity. These results have global implications for risk mitigation measures for nearby volcanoes. [Display omitted] • 1958–64 data suggests a 5–7 km deep reservoir below Irazú during 1963–65 eruption. • This reservoir is on top of the reservoir that feeds the 2010–2022 Turrialba eruption. • Irazú and Turrialba might share a mid-crustal reservoir. • Spatiotemporal distribution activity of ITVS might be controlled by tectonics. [ABSTRACT FROM AUTHOR]

Alaid Volcano on Atlasov Island is the northernmost and highest volcano of the Kuril island arc. The first time lavas were discharged by the terminal eruption of 2015–2016 was in October 2018. The samples were studied by petromagnetic, petrogeochemical, and microprobe techniques. The chemical composition of the 2015–2016 ejecta is very similar to that of the 1933–1934, 1972, and 1981 eruptions, attesting to a common deep source of magmas. That source can be inferred to lie at a depth greater than 50 km, judging from their potassium–sodium products and from estimates of the P–T conditions that prevailed during the precipitation of rock-forming mineral phases from the melt. It was for the first time that data were obtained concerning the structure and composition of the magnetic fraction in the Alaid igneous rocks, and the depth was determined for the last equilibrium state of magma during the 2015–2016 eruption. A joint analysis of the petromagnetic and petrogeochemical characteristics of the Alaid trachybasalts studied here revealed significant correlative relationships between (a) concentrations of Ti and Cu and petromagnetic concentration characteristics, (b) alkali elements (Li, Rb, Cs) and rare-earth elements and coercive petromagnetic parameters. [ABSTRACT FROM AUTHOR]

The GCOM-C (SHIKISAI) satellite was developed to understand the mechanisms of global climate change. The second-generation global imager (SGLI) onboard GCOM-C is an optical sensor observing wavelengths from 380 nm to 12.0 μm in 19 bands. One of the notable features is that the resolution of the 1.63, 10.8, and 12.0 µm bands is 250 m, with an observation frequency of 2–3 days. To investigate the effective use and potential of the 250 m resolution of these SGLI bands in the study of eruptive activities, we analyzed four practical cases. As an example of large-scale effusive activity, we studied the 2018 Kilauea eruption. By analyzing the series of 10.8 μm band images using cumulative thermal anomaly maps, we could observe that the lava effused on the lower East Rift Zone, initially flowed down the southern slope to the sea, and then moved eastward. As an example of lava dome growth and generation of associated pyroclastic flows, the activity at Sheveluch between December 2018 and December 2019 was analyzed. The 1.63 and 10.8 µm bands were shown to be suitable for observing growth of the lava dome and occurrence of pyroclastic flows, respectively. We found that the pyroclastic flows occurred during periods of rapid lava dome expansion. For the study of an active crater lake, the activity of Ijen during 2019 was analyzed. The lake temperature was found to rise rapidly in mid-May and reach 38 °C in mid-June. We also analyzed the intermittent activities of small-scale vulcanian eruptions at Sakurajima in 2019. The 1.63 µm band was useful for detecting activities that are associated with vulcanian eruptions. Analytical results for these case studies demonstrated that the GCOM-C SGLI images are beneficial for observing various aspects of volcanic activity, and their real-time use may contribute to reducing eruption-related disasters. [ABSTRACT FROM AUTHOR]

The early 21st century saw increased eruption activity of major volcanoes in the Northern Group of Kamchatka, namely, Sheveluch, Klyuchevskoy, Bezymianny, and the Tolbachik Fissure Zone. The growth of an extrusive dome on Sheveluch andesitic volcano has occurred, with the dome reaching a height of 600 m after 38 years of nearly uninterrupted eruption activity. An 8-year period of relative quiet was followed by ten summit eruptions and two lateral vent openings on the Klyuchevskoy basaltic volcano. Explosive–effusive eruptions were observed nearly every year on the Bezymianny andesitic volcano. A 36-year quiet period gave way to a new eruption in the Tolbachik regional fissure zone. [ABSTRACT FROM AUTHOR]

This paper analyzes the article published in Sankt-Peterburgskie Vedomosti (SPV) and a number of foreign studies addressing the natural cataclysm that occurred in Savoy (Western Alps) in 1751 and was recognized by witnesses as a volcanic eruption. This event was observed by V. Donati, a famous natural sc-ientist of the 18th century, and described by H.B. de Saussure, a prominent researcher of the Alps. Other evidence of similar phenomena in the Alps is presented from the historical data. It is suggested that a special type of explosive eruption, not accompanied by lava pouring out but still very dangerous may occur in the Alps. [ABSTRACT FROM AUTHOR]

A volcanic regime classifies a specific volcanic hazard state during which eruption episodes and events share similar frequency, magnitude, composition, and style. The post-AD 960 Maero Eruptive Period (MEP) at Mt. Taranaki (New Zealand) exemplifies such a distinctive eruptive period of volcanism. The deposits from intermittent eruptive episodes during this period built a pyroclastic fan on the northwestern flanks of the volcano. These deposits correlate to fall and thin pyroclastic density current deposits on other flanks. We have defined a sequence of 11 events via stratigraphy, radiocarbon dating, and geochemical studies. Each MEP episode involved lava dome growth and destruction from the summit crater. The deposits of the first MEP eruption episode cover deep palaeosols formed during a ~ 7000-year gap in activity on the NW volcano flanks. The first lava domes breached the western crater rim, and a large portion of the rim collapsed during the Newall episode c. AD 1360. This gave rise to increasingly hot and widespread block-and-ash flows. During the MEP, changes in magma composition reflect magma injection and mixing processes in small reservoirs. The episodes are classified into four scenarios, from high to low hazard impact: (1) dome collapse leading to Subplinian eruption, (2) explosive dome destruction and directed blast, (3) repeated rapid dome growth and large-scale hot dome collapse, and (4) slow dome effusion and partial collapse. The MEP defines a distinct volcanic regime, with the interval between the most recent MEP eruption and present > 50 years longer than any previous gaps between MEP episodes. As such, volcanic mitigation and forecasting at Taranaki must consider changes in hazard type if the current regime comes to an end. [ABSTRACT FROM AUTHOR]

This paper gives measured quantities, inclined distances, and elevations between geodetic monuments on the northeastern slope of Klyuchevskoi Volcano for the period from 1978 through 2014. Parasitic and summit eruptions were generally preceded by uplifts of the slope, while the termination of an eruption was accompanied by subsidence. The data from the longest series of observations of vertical displacements on the Kirgurich radial line during the period from 1979 to 2014 were used to determine an uplift of the slope that was increasing nearer to the crater. The maximum displacements occurred 2 years before the start of the 1983 parasitic eruption on the Predskazannyi vent and before the 2003–2004 and 2007 summit eruptions. A ground uplift of 12.5 microradians measured on a 17.8-km baseline was recorded in 2007. Farther from the crater, at a distance of 27 km from it, the vertical displacements were insignificant. We show that the measurement stations at heights of 2000 m to 3000 m were subject to deep creep, i.e., a sliding movement. The rates of movement at these stations reached 5–20 cm/yr. Significant horizontal displacements of geodetic monuments occurred near the parasitic eruptions of March 6, 1980 and March 8, 1983. All lines of measurements were observed to shrink by 5 to 20 mm in 1989‒1993 to 2014, indicating a compression for the northeastern slope of Klyuchevskoi Volcano. [ABSTRACT FROM AUTHOR]

Abstract There are many methods and scientific research approaches where modeling and understanding on how individuals evaluate natural origin risks. Despite the proficiency and depth of such studies, we evidenced a lack for a holistic approach where the most influencing factors in the individual decision-making process were covered. This research seeks to understand what those factors are, how they relate to each other, and how the behave with respect to individual perception and acceptance of risk. For this, we performed a thorough literature review covering the last decade in relation with the understanding of how these incidence factors affected the perception and acceptance of risk in the communities exposed to volcanic events under the decision-making process. Our research was able to detect how the identified variables influenced each other in this process. We analyzed different study cases found in the literature and, additionally, we propose as a further research a new theoretical approach related to decision-making modeling process under dynamic system that would be valuable as a contribution to risk management. [ABSTRACT FROM AUTHOR]

• The upper-crustal Vp/Vs ratios changed with volcanic evolution in Redoubt Volcano. • The Vp/Vs ratios decreased rapidly from 2.0 to 1.7 during the eruptions. • The Vp/Vs ratios change gradually in inter-eruption periods. Volcanic activities accompany changes in the physical and chemical properties of the medium. The ratio between P - and S -wave velocities, V P / V S , is sensitive to the medium property changes. We investigate temporal variations of the V P / V S ratios in the upper crust around Redoubt Volcano in the 1989–2014 time period using the traveltimes of local earthquakes. The V P / V S ratios reached ∼ 2.0 immediately prior to the 1989–1990 and 2009 eruptions. These high V P / V S ratios may be associated with partial melts in the edifice. The V P / V S ratios rapidly decreased to ∼ 1.7 during the 1989–1990 and 2009 eruptions due to decreasing temperatures, fluids, and pore pressures and increasing effective stresses after melt eruptions and gas emission. The change rates of the V P / V S ratios showed evident spatial distributions. The V P / V S ratios increased at a rate of 0.025 (± 0.003) yr−1 below the 2009 vent during the inter-eruption period between the 1989–1990 and 2009 eruptions due to an increase in the temperature, which may be associated with the recharge of the magma in the lower crust. The increase rate of the V P / V S ratios was as low as 0.005 (± 0.001) yr−1 in the regions located away from the eruption site. The V P / V S ratios appear to have increased consistently at a rate of 0.017 (± 0.004) yr−1 since the 2009 eruption. [ABSTRACT FROM AUTHOR]

We present an exposure analysis of infrastructure and lifeline to tephra fallout for a future large-scale explosive eruption of Sakurajima volcano. An eruption scenario is identified based on the field characterization of the last subplinian eruption at Sakurajima and a review of reports of the eruptions that occurred in the past six centuries. A scenario-based probabilistic hazard assessment is performed using the Tephra2 model, considering various eruption durations to reflect complex eruptive sequences of all considered reference eruptions. A quantitative exposure analysis of infrastructures and lifelines is presented primarily using open-access data. The post-event impact assessment of Magill et al. (Earth Planets Space 65:677-698, 2013) after the 2011 VEI 2 eruption of Shinmoedake is used to discuss the vulnerability and the resilience of infrastructures during a future large eruption of Sakurajima. Results indicate a main eastward dispersal, with longer eruption durations increasing the probability of tephra accumulation in proximal areas and reducing it in distal areas. The exposure analysis reveals that 2300 km of road network, 18 km of urban area, and 306 km of agricultural land have a 50% probability of being affected by an accumulation of tephra of 1 kg/m. A simple qualitative exposure analysis suggests that the municipalities of Kagoshima, Kanoya, and Tarumizu are the most likely to suffer impacts. Finally, the 2011 VEI 2 eruption of Shinmoedake demonstrated that the already implemented mitigation strategies have increased resilience and improved recovery of affected infrastructures. Nevertheless, the extent to which these mitigation actions will perform during the VEI 4 eruption presented here is unclear and our hazard assessment points to possible damages on the Sakurajima peninsula and the neighboring municipality of Tarumizu. [ABSTRACT FROM AUTHOR]

Calcic amphibole phenocrysts in the Tsurumidake summit (TS) lava, which was produced during the most recent eruption at Tsurumi Volcano (SW Japan) at around 7.5–10.5 ka, have been analyzed to determine the pre-eruptive conditions, such as temperature ( T ), pressure ( P ), oxygen fugacity ( f O 2 ), SiO 2 content (SiO 2 melt ), and FeO*/MgO ratio (FeO*/MgO melt ), of coexisting silicate melts in the magma reservoir beneath the volcano. Although most of the amphibole phenocrysts have been completely decomposed to a fine-grained opaque symplectite, ~ 6% of the grains remain intact. The degree of amphibole breakdown (DAB), defined as the ratio of the area of symplectite to the area of symplectite plus relict amphibole in each phenocryst, varies from ~ 20% to 100%. Compositional zoning was not observed in the amphibole grains, however, two distinct groups of amphibole phenocrysts have been identified based on their chemical compositions: group-I amphiboles, which are relatively Si-poor, and [6] Al-rich, and have a relatively high Mg# [100Mg/(Mg + Fe 2 + )]; and group-II amphiboles, which are Si-rich, and [6] Al-poor, and have a relatively low Mg#. Empirical equations for geothermobarometry, oxygen barometry and chemometry that exclusively rely on the amphibole composition were applied to estimate the T – P – f O 2 –SiO 2 melt –FeO*/MgO melt conditions of the silicate melts with which the amphibole crystals equilibrated. The results show that group-I and group-II amphiboles equilibrated with andesitic melts (group-I melts) and dacitic–rhyolitic melts (group-II melts), respectively. The T – P – f O 2 conditions of group-I melts were estimated as ~ 374–483 MPa (~ 13.9–17.9 km depth), ~ 950 °C, and NNO + 1.3, respectively, and those of group-II melts were ~ 93–242 MPa (~ 3.4–9.0 km depth), 824–913 °C, and NNO + 0.6–1.7, respectively. The estimated T – P – f O 2 –SiO 2 melt –FeO*/MgO melt conditions were almost constant for group-I melts, whereas the T , Δ NNO , and FeO*/MgO melt values of group-II melts decreased with increasing SiO 2 melt . The DAB decreased as the temperature increased; low-DAB grains are absent in group-II amphiboles. Our results suggest that (1) a deeper reservoir (at a depth of ~ 16 km) stored an andesitic melt coexisting with group-I amphiboles at ~ 950 °C; (2) a chemically zoned reservoir at shallower depth (~ 6.4 km) was filled with dacitic–rhyolitic melts that coexisted with group-II amphiboles at ~ 824–913 °C; (3) the TS lava was the product of magma mixing of at least three components, including the andesitic melt derived from the deeper reservoir, the dacitic and rhyolitic melts from the shallower reservoir and a mafic magma derived from the lower crust and/or upper mantle; and (4) the TS lava eruption occurred within a month or less of the magma mixing. [ABSTRACT FROM AUTHOR]

Eighteen years of heat flux data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) are used to investigate cycles of lava lake activity at Ambrym volcano in Vanuatu. Lava lakes are dynamic manifestations of open-vent volcanic behaviour and time-series analysis of this behaviour reveals the timing and magnitude of magmatic processes. Pulsatory fluctuations in heat flux of > 50 MW over periods of 30 to >100 days during lava lake activity are interpreted to represent episodes of magma replenishment. These are periodically interrupted by rapid falls in heat flux (50–100 MW over <5 days) or variations in the relative heat flux from lava lakes in different vents of the volcano, which are interpreted to represent changes to the shallow plumbing system feeding lava lake activity. Sudden lava lake drainage and flank eruptions can interrupt or terminate lava lake cycles. Heat flux patterns preceding such events do not show an obvious consistent pattern, suggesting that different magmatic processes may initiate these potentially hazardous surges in eruption intensity. Comparison with the dynamics of other lava lakes reveals similarities in long-term behaviour, despite differences in lava lake size, surface motion or degassing. Collectively this suggests fundamental similarities in the processes that sustain open-vent behaviour, including, the stability of magma supply, conduit-plumbing/geometry and local strain-state. • Heat flux data for lava lakes on Ambrym (Vanuatu) are presented. • Fluctuations in heat flux over weeks-months reflect changes to the shallow plumbing system feeding lava lake activity. • Heat flux patterns preceding lava lake drainage vary suggesting different magmatic processes can initiate these events. • Ambrym shares similarities in long-term behaviour with other lava lakes worldwide. [ABSTRACT FROM AUTHOR]

Surface displacements and edifice deformations at active volcanoes can occur when magma reservoirs begin to inflate as new magma enters them. Volcanoes are also subjected to a variety of external lithospheric stresses that are thought to be responsible for triggering volcanic unrest or modifying ongoing activity. However, despite many observations, it is uncertain whether these phenomena can actually interfere with magma chamber dynamics since it is not clear why some volcanoes are more subjected to these interactions than others. In order to determine whether external stresses interfere with volcanic activity, a viscoelastic 3D Finite Element Mogi-based model of Kīlauea volcano's magma chamber was implemented. First, the model was used to replicate an inflation cycle without external stresses. Its results were then compared with the ones obtained if the same model was subjected to tidal stress modulation and a strong ( M w = 7.7) tectonic earthquake. The model showed that tidally-induced pressurization is not sufficiently large to modify the pressure in a 5 km deep volcanic magma chamber, but it suggested how the magma chamber pressure build-up rate can be influenced by tidal pressurization and thus why some volcanoes seem to experience tidal interferences more than others. Furthermore, the model's results suggested why magma chambers are about the same size as calderas both on the Earth and on other Solar System silicate planets. System. Finally, it was used to propose an explanation of why a short-lived eruption at Kīlauea volcano, Hawai’i, began 30 min after the 1975 magnitude 7.7 ( M w ) Kalapana earthquake. [ABSTRACT FROM AUTHOR]

Channelized lava flows are commonly produced during the early stages of basaltic eruptions. These channels usually maintain their morphology until the eruption ends or discharge is diverted. In some instances, narrower channels can roof over, developing into lava tubes. We report here on a channelized flow erupted at Kīlauea volcano in 2007 that evolved into a "perched lava channel" composed of a string of interconnected, elongate lava pools, forming a lava channel/lava pool hybrid. The lava channel, which had a time-averaged discharge rate of ~3–9 m3/s, initially fed a series of flow branches that exhibited cooling-limited and volume-limited controls on flow length, sometimes with each process controlling a different morphological aspect of a single flow branch. The perched lava channel grew vertically primarily by overplating of the channel levees from frequent overflows, forming a compound flow field. This vertical growth only occurred when the distal end of the channel was blocked. When levee failure at the distal end of the channel caused the lava level in the channel to drop below the levee rim, no vertical growth occurred. Seeps of spiny lava and slabby pāhoehoe were common, erupting from uplift scarps on the channel levees, apparently fed by sills from denser, relatively crystal-rich material filling the bottom of the channel. We infer that lava in the channel was stratified in vesicularity and velocity, with foamy, vesicular, faster-moving lava at the top of the lava stream and denser, relatively outgassed, slower-moving lava filling the bottom of the channel. The channel levees were unstable, failing on several occasions, perhaps triggered by the levee seeps. The appearance of seeps, therefore, is one way of assessing the collapse potential of similar perched lava structures. • Detailed description of perched lava channel formed at Pu'u'ō'ō (Kīlauea) in 2007. • Perched lava channel exhibited characteristics of channelized flow and perched lava pool. • Flow lobes exhibited both cooling-limited and volume-limited length controls. • Vesicularity stratification caused vertical variation in flow rheology and velocity. • Seeps of outgassed lava burrowed through and destabilized channel levees. [ABSTRACT FROM AUTHOR]

Taiwan is subjected to several natural hazards such as extreme weather, seismic activity or tsunamis excited by earthquakes occurring along the Pacific Ocean subduction zones. Fortunately, Taiwan has not experienced any volcanic activity in historical times, a fact which reinforced the belief that its volcanic centers are by now extinct. During the past decade, volcanological, seismological and geochemical observations have shown that such a belief is erroneous and that two of Taiwan's volcanic centers (Tatun Volcano Group and Kueishantao island) have potential for future eruptive activity. Additionally, there is historical evidence for four submarine eruptions offshore the northern and eastern coast of Taiwan over the last 150 years. The types of volcanic hazards that may affect Taiwan's infrastructure and population are ashfall, pyroclastic flows, lava flows, landslides/volcanic debris avalanches, lahars, phreatic explosions and tsunami. Two of Taiwan's nuclear power plants (and a third whose construction has been temporarily suspended) are close to the volcanic centers and could be affected by ashfall and lava flows, an issue that needs to be addressed by the operator of the plants. Even though the probability of future volcanic activity is low, it has to be recognized that the vulnerability to volcanic hazards for an advanced technological society such as Taiwan's has increased considerably. Volcanic risk therefore cannot be considered insignificant, and its mitigation has to be addressed by a co-ordinated research/monitoring program. Furthermore, the development of contingency plans is a must for such high risk phenomena even if they are considered 'low probability' events. [ABSTRACT FROM AUTHOR]