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Explosive volcanic eruptions can inject sulfur dioxide (SO2) into the stratosphere to form aerosol particles that modify Earth’s radiation balance and drive surface cooling. Eruptions involving interactions with shallow layers (≤500 m) of surface water and ice modify the eruption dynamics that govern the delivery of SO2 to the stratosphere. External surface water controls the evolution of explosive eruptions in two ways that are poorly understood: 1) by modulating the hydrostatic pressure within the conduit and at the vent, and 2) through the ingestion and mixing of external water, which governs fine ash production and eruption column buoyancy flux. To make progress, we couple one-dimensional models of conduit flow and atmospheric column rise through a novel “magma-water interaction” model that simulates the occurrence, extent and consequences of water entrainment depending on the depth of a surface water layer. We explore the effects of hydrostatic pressure on magma ascent in the conduit and gas decompression at the vent, and the conditions for which water entrainment drives fine ash production by quench fragmentation, eruption column collapse, or outright failure of the jet to breach the water surface. We show that the efficiency of water entrainment into the jet is the predominant control on jet behavior. For an increase in water depth of 50–100 m, the critical magma mass eruption rate required for eruption columns to reach the tropopause increases by an order of magnitude. Finally, we estimate that enhanced emission of fine ash leads to up to a 2-fold increase in the mass flux of particles < 125 μm to spreading umbrella clouds, together with up to a 10-fold increase in water mass flux, conditions that can enhance the removal of SO2 via chemical scavenging and ash sedimentation. On average, compared to purely magmatic eruptions, we suggest that hydrovolcanic eruptions will be characterized by reduced climate forcing. Our results suggest one possible mechanism for volcano-climate feedback: temporal changes with climate in surface distributions of water and ice may modify the relative global frequency or dominance of hydrovolcanic eruption processes, modulating, in turn, global patterns in volcano-climate forcing.

This study provides the first micro-thermometric data of fluid inclusions (FIs) in mafic loose (disaggregated) xenocrysts and ultramafic xenoliths in explosive products of the melilitite-carbonatite Mt. Vulture volcano (southern Italy). Pure CO2 late stage FIs hosted in rock-forming minerals of wehrlite xenoliths and clinopyroxene xenocrysts were trapped at the local crust-mantle boundary (32 km). In contrast, trapping pressures within the loose olivine xenocrysts are from 3.2 to 4.5 kbar (8–13 km). Considering the ongoing degassing of mantle-derived CO2 rich gases, together with seismic evidences of the presence of low amount of melts at depth, and the tectonic control of the past volcanic activity, our study opens new perspective about the hazardous nature of the “quiescent” melilitite-carbonatite volcanoes.

The ���Ciampate del diavolo��� geosite is unique in the World due to its geological and anthropological peculiarities. Finding hominin footprints on the ignimbrite deposits of 350,000 years ago, imprinted in the period of greatest activity of the volcano, opens up numerous questions about the palaeoenvironmental conditions of the volcano and the complex processes that allowed the generation and conservation of the footprints. The note pays particular attention to the framing of the volcano's activity and to the features of deposits of the Brown Leucitic Tuff series, as the human fossil footprints known as "Ciampate del Diavolo" are preserved on the surface of one of the highest units in the sequence., Il sito delle ���Ciampate del diavolo���, sul fianco nordorientale del vulcano Roccamonfina, ��� un sito unico al Mondo grazie alle sue peculiarit��� geologiche ed antropologiche. Il ritrovamento di impronte di hominini al di sopra di un deposito ignimbritico, impresse in nel periodo di maggiore attivit��� del vulcano, d��� spazio a numerose questioni circa le condizioni paleoambientali esistenti sul vulcano ed i complessi processi che hanno permesso la formazione e la conservazione delle impronte. La nota dedica particolare attenzione al contesto dell���attivit��� del vulcano ed alle caratteristiche della serie dei Tufi Leucitici Bruni, in quanto le impronte note come ���Ciampate del diavolo��� sono presenti sulla superficie di una delle unit��� pi��� alte della sequenza di questi tufi.

Popocatepetl is one of the most active volcanoes in North America. Its current predominantly mild activity is contrasted by a history of large effusive and explosive eruptions and sector collapse events, which was first summarised by Espinasa-Perena and Martin-Del Pozzo (2006). Since then, a wealth of new radiometric, geophysical and volcanological data has been published, requiring a re-evaluation of the evolution of the Popocatepetl Volcanic Complex (PVC). Herein, we combine existing literature with new field observations, aerial imagery and digital elevation model interpretations to produce an updated and improved reconstruction of the growth and evolution of the PVC through all of its history. This will be fundamental for the assessment and mitigation of risks associated with potential future high-magnitude activity of the PVC. The PVC consists of four successive volcanic edifices separated by three sector collapse events producing avalanche deposits: Tlamacas (>538 - >330 ka, described here for the first time), Nexpayantla (∼330 - >96 ka), Ventorrillo (∼96 ka - 23.5 ka) and Popocatepetl ( Supplementary material:https://doi.org/10.6084/m9.figshare.c.5709190

Magma is commonly thought to be stored as a crystal-rich mush within vertically extensive, crustal storage regions. A key unknown is how to remobilise and erupt such crystal-rich material, and whether the growth of gas bubbles within the mush could promote remobilisation. In order to investigate this, we need improved constraints on the timing of volatile saturation in magmas. The mineral apatite represents a potentially useful record of pre-eruptive magmatic volatiles, but data interpretation is complex because exchange reactions control the volatile partitioning. Model solutions are therefore non-unique. Here, we present a numerical forward modelling program with a sensitivity analysis function, which addresses non-uniqueness by identifying alternative sets of starting parameters that match a target compositional trend through a population of apatite crystals. The model is applied to a new dataset of volatiles in apatite from the 12.9 ka Laacher See eruption, Eifel volcanic region, Germany. The results indicate that the magma was initially strongly volatile-undersaturated and became saturated through progressive crystal fractionation. Apatite crystals are not in volatile or trace element equilibrium with their carrier melts, indicating dispersal of crystals into different chemical environments. Consideration of apatite diffusivities suggests that this reorganisation occurred shortly before eruption. Our modelling results also allow us to constrain directly the amount of pre-eruptive magmatic vapour emitted during the explosive eruption, highlighting the importance of considering the behaviour of halogens during magma storage. Overall, our approach confirms the value of measuring apatite volatile contents and highlights the potential of this method to provide quantitative constraints on magmatic evolution and storage conditions.

Volcanoes can pave their surroundings with lava, send clouds of hot ash downslope to smother cities, and even generate massive tsunamis. The most recent high-profile eruption on the Canary Islands spawned viral videos of slow, steady folds of smoldering lava enveloping houses and swimming pools. A volcano’s plume, such as this one from the 2009 Sarychev Peak eruption on the Kuril Islands in the Russian Far East, can send long-distance signals that indicate an eruption has occurred. Image credit: NASA/Mike Barratt (photographer). But the perils volcanoes pose aren’t limited to ground level: Their ash plumes threaten aircraft passing overhead, even those flying at cruise altitude. In the case of a sudden and explosive eruption, those clouds of ash—which are in fact small bits of rock—can reach elevations of 10,000 meters in just a few minutes. Despite these impressive displays, volcanic eruptions, especially remote ones situated far away from seismic instruments, can be hard to detect. There are some clues: Plume-induced lightning often betrays the presence of ash clouds once they’ve reached high altitude. But recent studies suggest that a different kind of electrical discharge—one generated near the base of a volcanic plume and nowhere else—could provide researchers with a heads-up that an eruption has commenced. Another analysis hints that other unseen signals, the low-frequency warbles known as infrasound, could help researchers monitor changes in ongoing eruptions that signal danger for people nearby. Dozens of aircraft have had run-ins with plumes of volcanic ash, although none of these encounters has been fatal. One of the most dramatic encounters occurred in December 1989 when KLM flight 867 from Amsterdam ran into an ash cloud as it approached its destination in Anchorage, AK. Ash sandblasted the plane’s windshields; airspeed sensors began to give false readings and then failed. All four engines died; the …

The previous chapters explained the mechanism of each individual process (elementary process) involved in the vesiculation and crystallization of magma; the overall time evolution of the vesiculation process and the crystallization process comprising the elementary processes; the roles of physical properties in the processes; and shared the accuracy and limits of theoretical understanding compared with experiments. This chapter introduces the examples of interpreting the texture of volcanic products and readings of quantitative information from them by applying the understanding achieved to date. Keeping correspondence with eruption styles in mind, this chapter deals with actual data obtained from the texture analysis of eruptive products and applies the understanding achieved to date to the actual data to quantitatively understand eruptive phenomena in the order of explosive eruptions and nonexplosive eruptions. The last section describes the application to intrusions. Moreover, the bubble texture and crystalline texture are separately explained.

Mudeungsan (Mount Mudeung) is an extinct volcano located in the southwestern part of South Korea that was formed in the Late Cretaceous period. This mountain, 1187 m above sea level, is adjacent to Gwangju Metropolitan City, which has a large population (about 1.4 million) and volcanic rocks, including columnar joints, which form various types of outcrops. Although this mountain was listed as a national geopark in 2014 and a UNESCO Global Geopark in 2018, much basic research has yet to be carried out. In particular, there are no mineralogical studies of volcanic rock samples despite the well-preserved variety of volcanic rocks. For this study, X-ray diffraction analysis was conducted using rock samples from Mudeungsan columnar joints known as tuff. We report that the rocks are mostly dacite, mainly composed of quartz, plagioclase, and sanidine through Rietveld quantitative analysis. In particular, α-cristobalite, a crystalline polymorph of silica, appears in the columnar joint rocks, indicating that Mudeungsan experienced an explosive eruption during the formation of the mountain.

Co-auteur étranger; International audience; The variability in intensity and style shown by explosive volcanism has been traditionally explained by a complex interplay among melt composition and pre-eruptive volatile content, which modulate magma ascent and conduit dynamics. However, magmas having similar compositions may becharacterized by subtle textural changes affecting magma rheology and eventually explosive dynamics. Here we study five eruptions occurred at Cotopaxi volcano (Ecuador) in the last 2000 years characterized by a small variation in magma composition but spanning a wide range of intensity to investigate how these parameters control variations in eruption dynamics. We combined eruption source parameters (ESPs), obtained from the application of recent models to all the available field data, with new textural data and state-of-the-art conduit dynamics modeling. We found that, despite having variable microlite content and texture, the effect of microlite on magma rheology is partly counterbalanced by variablephenocryst abundance, resulting in a comparable total crystal content. The combination of modeling results with textural data and ESPs suggests that subtle variability in crystal content and magma composition may be accompanied by strong feedback effects among crystallization, changes in melt/ magma viscosity and volatile exsolution, with microlite crystallization resulting in a rapid change of magma rheology and modifications in the explosive dynamics. By combining ESPs with quantitative textural data (i.e. melt normalized vesicle number density) and conduit modeling, we also show how general observed correlations between composition and texture of juvenile products with eruption intensity are not evident when applied to eruptions characterized by a small compositional range.

Changbaishan Tianchi volcano is one of the most famous active volcanoes in Northeast Asia. Its Millennium eruption (ME, 946–947 CE) is considered to be one of the largest explosive eruptions over the past 2000 years, which had produced widely distributed tephra layer across Northeast Asia. However, little attention has been paid to the tephra buried in peatlands around this volcano. Here we present petrographic, geochemical and AMS14C data of the volcanic glasses within a new discovered macro-tephra layer buried in the Yueliangwan peatland, northeast China. The results suggest that buried tephra was the product of Changbaishan Millennium eruption. The eruptive sequence of the ME included comendite eruption and trachyte eruption from bottom to top. Tectonic background analyses reveal that Changbaishan Tianchi volcano regions belong to the anorogenic within plate back-arc extensional tectonic environments. Eruptive and sedimentary processes of the buried tephra were postulated as follows: a large amount of volcanic glasses formed through the eruption of trachyte magma that had high contents of rare earth elements (REE) and trace elements (TE). Then, fine grained volcanic glasses were sprayed into the atmosphere and transported to the Yueliangwan areas. The volcanic glasses deposited and formed airborne pumice layer. This buried tephra layer would act as a key isochronous marker horizon for the chronological framework in a range of sedimentary contexts across Northeast Asia. And it provides accurate eruptive sequence of Changbaishan Millennium eruption. This study would attract more attentions on the buried tephra in peatlands around active volcanoes, which would be of significance for the reconstructions of volcanic eruption history.

Mafic volcanism accounts for 80% of magmas erupted on Earth. Although the majority of these eruptions are effusive to Strombolian and fountain-fed, large explosive mafic eruptions do occur. This work uses the deposits and pyroclast textures from the 12.6 ka Curacautin ignimbrite eruption of Llaima volcano to constrain the conditions that drove this mafic explosive eruption and extrapolate the findings to provide insights into the conditions that promote large-volume, mafic explosive volcanism elsewhere. The Curacautin ignimbrite (Ci) consists of four massive coarse ash to lapilli tuff flow units; Unit 1 is at least 30 m thick in proximal exposures, and Units 2–4 range from 1 to 4 m thick. New 14C dates and field observations suggest the Ci is the result of a single eruptive episode at ~12.6 ka. A lack of fall deposits and presence of abundant clast agglutination suggests the Ci eruption was a boil over event. We estimate the proximal Ci tephra volume to be between 6 and 9 km 3 (equivalent to 3.5–4.5 km 3 DRE), which is less than previous estimates. Even with our lower estimate, the Ci is still larger than the Masaya Triple Layer, Pucon ignimbrite, Tarawera 1886, and Etna 122 BCE mafic eruptions. Average vesicularities of pyroclasts range from 43 to 71%, and all but one exposure have vesicularities ≤56%. Average phenocryst content is ≤1–3%, but plagioclase microlite crystallinities are between 29 and 44%, with volumetric number densities between 8.21 × 10 6 and 1.84 × 10 7 mm −3 . Such high microlite content suggests high disequilibrium resulting from rapid magma ascent and decompression. We interpret that the combination of rapid ascent and increased magma viscosity due to the crystallization of microlites caused gases to remain coupled with the Ci magma. This, in combination with ash textures, suggests the Ci eruption explosivity was driven by brittle fragmentation. Assuming that mass eruption rates exceeded 2.0 × 10 8 kg s − 1 to produce complete column collapse, we estimate an eruption duration of ~15–17 h. This study further supports the interpretation that extensive microlite nucleation from rapid ascent can lead to large mafic explosive eruptions.

The 2020 eruption of the Nishinoshima volcano, Japan, emplaced new lava flows as well as numerous ash plumes from explosive eruptions. Several of these plumes were imaged by the Advanced Spaceborne Thermal Emission and reflection Radiometer (ASTER) as part of the Urgent Request Protocol (URP) during July 2020. Linear spectral deconvolution was used to model ASTER thermal infrared (TIR) data using the ASTER Volcanic Ash Library (AVAL), a spectral library containing volcanic ash compositional and particle size range end members. The airborne ash plume best matched the andesite library end member suites having a significant fine ( 63 μm were also detected downwind, and distally around the cloud edges, assumed due to sampling of lower levels of the plume containing these larger particles even as the optical depth remains high. These results demonstrate that both composition and particle size variations within a plume can be estimated from the high spatial and spectral resolution ASTER TIR data using this approach, provided that representative spectral end members are present in AVAL and where the plume remains opaque to upwelling radiance.

The Sierra Nevada Volcanic Range (SNVR), which includes Popocatépetl, Iztaccíhuatl and Tláloc-Telapón volcanoes, has been the source of multiple large explosive eruptions that have dispersed tephra across central México. Several eruptions since 40 ka have previously been described, particularly from Popocatépetl, the southernmost volcano of the range. However, the longer-term eruption history of the SNVR is poorly understood, due to challenges with correlating limited exposures of older pyroclastic sequences, and in discriminating between tephras derived from different sources. Here we describe two extensive exposures located between Popocatépetl and Iztaccíhuatl volcanoes, which provide a more complete and longer-term explosive eruption record of the SNVR: the Nepopualco and Xalitzintla tephra sequences. A detailed tephrostratigraphic survey, together with new40Ar/39Ar geochronological analyses and glass geochemistry, has permitted the characterization of identified eruption units further leading to the determination of geochemical fields for each volcano and the subsequent discernment of volcanic sources. Our results show that, since the collapse of Los Pies Cone, which destroyed the Paleo-Iztaccíhuatl edifice at 631 ± 44 ka (2σ), Iztaccíhuatl has produced at least 6 explosive rhyolitic eruptions. After coeval activity with Popocatépetl, between ~600 and ~ 500 ka, Iztaccíhuatl's explosive activity ceased while Popocatépetl's continued until present day. Popocatépetl has produced at least 27 medium to large explosive eruptions (inferred VEI 4–6), commonly of andesitic to dacitic compositions. Some of these eruptions deposited pumice fallout of >1 m thick in both the Nepopualco and Xalitzintla sequences (e.g. the 339 ± 16 ka [2σ] NT-23/WRT-7 eruption), suggesting that Popocatépetl has produced several eruptions similar in magnitude to well-known the ~14 ka Tutti Frutti Pumice (a VEI 6 eruption with a ~ 5 km3tephra volume). The Popocatépetl and Iztaccíhuatl tephras are interbedded with deposits from more distal volcanoes, including some mafic to intermediate products of unknown sources (possibly from nearby monogenetic cones) and tephras related to the late Pleistocene eruptions of Tláloc-Telapón (including the tephra layer produced by the San Valentin Ignimbrite, recently40Ar/39Ar dated in this study at ~102 ka; 2σ). Our new chemical, stratigraphic and geochronologic investigations of these pyroclastic deposits, predominantly from Popocatépetl and Iztaccíhuatl, provide information on the scale and frequency of medium to large magnitude explosive eruptions over a longer-time period than currently known and that have had potential to disperse tephra across central México since the middle to late Pleistocene. This new data can be used to determine the source of further unknown tephras in the region as well as to better assess the volcanic hazard to the densely populated megalopolis of México City.

Kambalny is the southernmost volcano in the Kamchatka Peninsula. After a long repose stage, on March 24, 2017, it produced a strong phreatic eruption, which ejected an ash cloud to the distance of up to 1000 km. In summer 2018, we deployed ten seismic stations in the vicinity of Kambalny for one year. Data from this network and the only permanent station located at ~20 km from the volcano provided arrival times of P and S waves for this study. We used them to localize earthquakes and obtain the 3D distributions of velocities of the P (Vp) and S waves (Vs), also mapping the Vp/Vs ratio down to a depth of ~10 km. We identify an anomaly of high Vp/Vs ratio in the depth interval of 7–10 km, and interpret it as a magma reservoir responsible for Holocene activity of Kambalny. This reservoir appears to be connected with the volcano edifice by a linear zone of high Vp/Vs ratio, which may represent a system of fractures originated during the eruption in March 2017 and served as a pathway for magma ascent. We propose that the interaction of hot magma with meteoric fluids in shallow layers caused active boiling and steam formation in a closed reservoir below the volcano. After exceeding a critical pressure, the steam escaped to the surface causing an explosive eruption. We also found evidence that geothermal fields located to the north and northwest of Kambalny might be fed from separate deep sources.

Dieng area as an important and productive area needs the support of various aspects in encouraging regional growth and development. This region also has been experiences many disasters year by year. Disasters due to volcanism are events that cause many losses, especially casualties in the past. Discussions about potential disasters in the Dieng area should not only be limited to volcanism and earthquakes as hazards caused by endogenous processes. The Dieng area is an old landscape. As an old landscape that is heavily influenced by exogenous factors from a wet tropical climate, other potential hazards in the form of geomorphological hazards also need attention. In fact, there are some geomorphological hazards that occur due to the complexity of the landforms of this area, there are various processes that often occur such as mass movement and erosion and these processes usually have a negative impact on social and economic life. This paper aims to analyze the various types and levels of geomorphological hazards that exist outside of the Dieng Volcanic Complex. This region has experienced major eruptions in the past. At present, in the post-explosive era, it is necessary to know whether geomorphological hazards are limited to eruptions or if other hazards are a bigger threat. The terrain survey method or geomorphological survey is a field observation method used to achieve research objectives. The interpretation of remote sensing images, literature research, and documentation provides support in the form of additional data to complement the primary data from the observation. The results obtained show that the area of the Dieng Volcanic Complex after the explosive eruption era, which is largely composed of volcanic landforms, which physically dominates the denudation process. The denudation process is what causes mass movement and erosion to emphasize that there is a very high potential geomorphological hazard in this research location. This research area is also a productive agricultural production area. Although it cannot be separated from criticism because of its negative impact on the environment, because in the use and management of land carried out by the community it affects mass movement and erosion. Therefore, information on geomorphological hazards is very important to be provided and updated continuously in the interest of ensuring effective and sustainable disaster management.

The Malinche Pumice II is a fallout deposit produced by a Plinian-type eruption during the Pleistocene-Holocene at La Malinche volcano. La Malinche (4461 masl) is an active stratocone located in central Mexico, in the Trans-Mexican Volcanic Belt province. It is 26 km to the NE of the City of Puebla and 22 km to the SE of the City of Tlaxcala. The Malinche Pumice II was produced by one of the largest explosive eruptions of this volcano, involving a dacitic magma (63.6–65.3 wt% SiO2, anhydrous basis) with a mineral assemblage of plagioclase + amphibole + Fe Ti oxides and ± biotite phenocrysts. Larger plagioclase crystals are up to 1.2 mm in diameter, with resorbed margins and complex zoning (An26 to An43), whereas microcrysts are euhedral with homogeneous composition (An42 to An55). Amphibole is mainly magnesio-ferri-hornblende (Mg# = 0.65–0.82) and lesser amounts of pargasite. Geothermometry performed using Fe Ti oxides yields an average temperature of 873 ± 2 °C and oxygen fugacity of 1.8 units above the NNO buffer. Amphibole geothermobarometry yields a lower temperature (809 ± 19 °C) and a pressure of 230 ± 100 MPa, assuming 4.4 wt% of H2O. Considering an average density of 2650 kg/m3 for the upper crust in central Mexico, the storage region of the Malinche Pumice II dacitic magma was located at 8 ± 2 km depth. Biotite could be antecrystic or xenocrystic in origin, based on its reacted texture, large sizes (0.85–2 mm), and reaction rims. Similarly, pargasite that provides higher temperature estimates (900 ± 18 °C) and low anorthite plagioclase (An26) could also be antecrysts or xenocrysts. The Plinian eruption was likely triggered by an input of a hotter and deeper magma batch that overpressurized the dacitic magma system that eventually provoked vesiculation and fragmentation. The eruption shifted to a hydromagmatic style because of external water's entrainment that decreased the vesicularity of pumice. Our results are in good agreement with recent seismicity recorded at depths of ~7 km probably associated with activity of the Malinche's magmatic system.

The Orocaima SLIP consists of an association of acid-intermediate volcanic-plutonic rocks. The volcanic rocks were generated in explosive eruptions through low eruptive columns, probably associated with fissural volcanism in the north of the Amazonian Craton, Brazil, between 2.0 and 1.98 Ga. It generated ignimbrites, whose facies (volcanic breccia rich in lithic, lapilli-tuff and lithic lapilli-tuff) show the proximity of the source. The extensive area of ca. 200.000 km2 of ignimbrite, rhyolite and dacite deposits, as well as the age range (2.0–1.98 Ga) and geochemical signatures suggest that the Orocaima volcano-plutonism may correspond to one of the oldest silicic LIPs in the world. The silicic volcanism is essentially subaerial and characterized by high-grade ignimbrites (densely welded) and subordinate lava, the ages of which indicate the longevity of the volcanic event in the Orosirian. They are included in the Surumu Group and comprise rocks with high-K calc-alkaline affinities and were emplaced in a subduction-related setting, similar to the rocks that extend through Venezuela, Guyana and Suriname (Cuchivero-Surumu-Iwokrama-Dalbana metavolcanic belt - CSID). The occurrence of mafic fragments disseminated in volcanic and granitic rocks in the north of Roraima, Brazil and in other segments of the CSID belt suggests the coexistence of acid and basic magmas. Except for one sample (eNd(t) = -2.3), the Nd isotopic data of analyzed Surumu Group volcanic rocks yielded positive eNd(t) values (0.5–4.48; TDM = 2.0–2.47 Ga), suggesting generation from magmas derived from the mantle or from the melting of new juvenile crust. The Orocaima volcanism bears no evidence of involvement of Archean sources in the generation of the rocks. Thus, the Orocaima volcano-plutonism may represent one of the most significant ignimbrite eruption events during the Palaeoproterozoic in the world.

Several global databases of eruption properties have been developed in recent years, which contain eruption age, eruption magnitude, eruption style, and volcanic explosivity index. However, their examinations of the relationships between eruption and magmatic properties remain qualitative. To explore such relationships, we sampled and petrologically analyzed the eruptive products and have constructed a database of magmatic properties of erupted magmas at Japanese arc volcanoes during the last one hundred thousand years. The 43 erupted magmas were characterized not only by bulk SiO2 content, but also by preeruptive melt SiO2 (inferred from groundmass SiO2 content) and phenocryst contents, which are the second most straightforward proxies of physical and thermodynamic properties of preeruptive magmas. Sample data were collected through a unified procedure using chemical and image analyses and mass balance calculations to obtain groundmass compositions and phenocryst contents. We examined the relationships between magmatic properties and eruption magnitude, M, as the most representative eruption property. Our database includes explosive eruptions of M 3 to 8. By incorporating available literature data for 17 eruptions, we examined 60 eruptions in total. This study distinguished magmas from the bulk composition (e.g., basaltic, andesitic, dacitic and rhyolitic magmas) or melt composition (e.g., basaltic, andesitic, dacitic and rhyolitic melt-bearing magmas). Our results show that the maximum eruption magnitude gradually increases with increasing bulk SiO2 content. The maximum eruption magnitude shows a sharp increase around the compositional boundary between dacitic and rhyolitic melt-bearing magmas. For the eruptions of rhyolitic melt-bearing magmas, the maximum eruption magnitude decreases with increasing phenocryst content. The largest magnitude eruptions (M 8) were of rhyolitic melt-bearing, phenocryst-poor magmas. We compared our data for Japanese arc volcanoes with data for global volcanoes. Despite their different tectonic settings, most eruptions globally are consistent with the pattern observed for eruptions at Japanese arc volcanoes. Notable deviations are supereruptions (M > 7) of monotonous intermediate magmas that occurred more than a million years ago. Although more examination is needed, especially for smaller and effusive eruptions, the observed relationships suggest that melt SiO2 and phenocryst contents are related to maximum eruption magnitude, and should be fundamental components to characterize volcanoes and eruptions in future databases studies.

The utility of infrasound technology for detecting explosive eruptions is well established. However, many active volcanoes are currently monitored exclusively with seismic networks and lack infrasonic sensor networks. Here, we demonstrate the ability of template matching to automatically detect ground-coupled airwave signatures (infrasound signals recorded on seismometers), associated with mild to large explosive eruptions in continuous broadband displacement waveforms from Popocatepetl volcano, Mexico. As templates, we use five verified high-amplitude ground-coupled airwave signals that were recorded in November 2017 by both a temporary broadband infrasound array co-located with a broadband seismometer at station ATLI (15.8 km range) and a permanent broadband seismic monitoring station PPIG (4.9 km range). We systematically apply the template matching procedure to two years of continuous seismic records from PPIG station (2017–2018), to identify ground-coupled airwaves in a time span exceeding the operation time of the temporary infrasound array at ATLI. We identify 43 ground-coupled airwaves that occurred during the period of study and with absolute correlation coefficients of 0.5 ≤ |R