Distribution Of Volcanoes Research Articles

JIRAM Observations of Volcanic Flux on Io: Distribution and Comparison to Tidal Heat Flow Models

AbstractJuno has allowed clear, high‐resolution imaging of Io's polar volcanoes using the Jovian Infrared Auroral Mapper (JIRAM) instrument. We have used data from JIRAM's M‐band (4.78 μm) imager from 11 Juno orbits to construct a global map of volcanic flux. This map provides short‐term insight into the spatial distribution of volcanoes and the ways in which high‐ and low‐latitude volcanoes differ. Using spherical harmonic analysis, we quantitatively compare our volcanic flux map to the surface heat flow distribution expected from models of Io's tidal heat deposition (summarized in de Kleer, Park, et al. (2019, https://doi.org/10.26206/d4wc‐6v82). Our observations confirm previously detected systems of bright volcanoes at high latitudes. Our study finds that both poles are comparably active and that the observed flux distribution is inconsistent with an asthenospheric heating model, although the south pole is viewed too infrequently to establish reliable trends.

The spatiotemporal evolution of monogenetic scoria cones in the Paricutin-Tancítaro region, Mexico: Results from a Morpho-chronological analysis and its consequences on the distributed volcanic hazard

The Paricutin-Tancítaro region (PTR) within the Michoacán-Guanajuato monogenetic Volcanic Field (MGVF) is characterized by a large stratovolcano, Tancítaro enclosed in a dense distribution of monogenetic volcanoes, mainly scoria cones, that includes the well-known Paricutin. The succession of seismic swarms beginning 54 years after the birth of Paricutin in 1943 represents a challenge for apprising the region's volcanic and seismic hazards. In this work, we introduce a novel methodology to assess the spatiotemporal evolution of the monogenetic scoria cones and the distributed volcanic hazards. We first performed a morpho-chronometric analysis of 171 scoria cones to estimate their relative ages, which revealed an increasing trend in the rate of monogenetic eruptions over the last 120 kyr, especially in the last 20 kyr, with a current mean waiting interval between monogenetic eruptions of only 120 yr. In a second step, we estimate the spatiotemporal evolution of monogenetic volcanic activity in PTR using a Voronoi tessellation to represent the spatial density distribution of scoria cone emplacement through time to detect dynamic shifts in volcanic activity locations in the region. This approach thus reveals spatial dynamic patterns in the rates of monogenetic eruptions over time. Subsequently, a Poisson process is assumed to estimate the spatially distributed cone-forming eruption probabilities based on the morpho-chronometrically analyzed cones. Remarkably, a high spatial correlation was found between the areas with the highest probabilities and the location of the recent seismic swarms recorded in the PTR.

Io's Long‐Wavelength Topography as a Probe for a Subsurface Magma Ocean

AbstractWe investigated how spatial variations in tidal heating affect Io's isostatic topography at long wavelengths. The long‐wavelength relief is less than the 0.3 km uncertainty in Io's global shape. Assuming Airy isostasy, degree‐2 topography <0.3 km amplitude is only possible if surface heat flux varies spatially by <19% of the mean value. This is consistent with Io's volcano distribution and is possible if tidal heat is generated within and redistributed by a convecting layer underneath the lithosphere. However, that layer would require a viscosity <1010 Pa s. A magma ocean would have low enough viscosity but would not generate enough tidal heat internally. Conversely, assuming Pratt isostasy, we found ∼0.15 km degree‐2 topography is easily achievable. If a magma ocean was present, Airy isostasy would dominate; we therefore conclude that Io is unlikely to possess a magma ocean.

Stress field in northeastern Japan and its relationship with faults of recent earthquakes

Inversion tectonics, in which old normal faults act as reverse faults in current stress fields, are frequently observed in northeastern Japan (Tohoku District); however, the conditions that control these fault activities remain unclear. To improve the identification of faults that are more favorable to slip under current stress conditions, the regional fault mechanisms in the Tohoku District must be better understood. The stress field in the Tohoku District and the likelihood of fault activities were thus estimated using slip tendency (ST) analysis. The results show that in the eastern margin of the Japan Sea (EMJS), the reverse fault type is dominant in the stress field. The maximum horizontal direction changes clockwise from E–W to NW–SE from the northern to the southern regions and counterclockwise from NW–SE to E–W from the Japan Sea to the inland area. In the Tohoku inland area, the estimated direction of the maximum horizontal axis changed after the 2011 Tohoku-Oki earthquake, from E–W to WNW–ESE. ST values were calculated for seven events in the EMJS area. To avoid the influence of the Tohoku-Oki earthquake, only stress field data prior to the 2011 Tohoku-Oki earthquake were used to determine ST values for four of the events in the Tohoku inland area. The results showed eastward-dipping fault planes with low dip angles (approximately 30°–45°) and large ST values (approximately > 0.7). The large ST values indicate that the stress field fault is favorable to slip and the results were consistent with the actual fault plane in the EMJS area. However, in the Tohoku inland area and the southern part of fault model of the 1993 Hokkaido Nansei-Oki earthquake, fault planes with large ST values were found to be inconsistent with the slipped fault plane, thus indicating that slipping was unfavorable. The regional differences are consistent with the volcano distribution and thus, the fluid supply from volcanic activity may have helped the fault slip under difficult stress conditions.Graphical

Opposite rotations in the Central Andes Bend: Tectonic scenario compared to other cases of opposite rotations and implications for long-term subduction at continental arcs

A review confirms opposite paleomagnetic rotations on the northwest and southeast limbs of the Central Andes Bend in Peru, Bolivia, northern Chile and Argentina. Counter-clockwise rotations occur NW of an ENE-oriented axis extending from Arica on the Chile coast to Santa Cruz, Bolivia, with clockwise rotations to the south and SE. Rotations have been measured in all the curvilinear provinces from the Western Cordillera via the Altiplano/Puna to the Eastern Cordillera, InterAndean and SubAndean belts. Although several processes have been postulated, the zone coincides with flat-slab subduction, possibly related to underthrusting of oceanic plateaux. The curvilinear subduction zone is convex in the direction of subduction. Shortening associated with compression and uplift migrated east-northeastwards towards the SubAndean belt from Mid Eocene to Recent and is greatest at the axis of the bend. The area may be segmented with rotations facilitated by strike-slip fault zones: CCW rotations relate to sinistral strike-slip whereas CW rotations are associated with dextral strike-slip. Additional compartmentalisation is here suggested based on volcano distribution, regularly spaced giant copper porphyry deposits, offsets of thrust anticlines, and isolated foreland basins. This tectonic scenario is contrasted with other identified cases of opposite microplate rotations which are usually linked to rollback of a subduction zone which is concave in the direction of subduction. In these cases, CW rotations also relate to dextral strike-slip, and CCW rotations to sinistral strike-slip, but their distributions change if the slab changes from convex to concave in the direction of subduction. These observations provide a model for long-lived subduction at continental arcs where flat-slab subduction switches to rollback over time, such as Pacific China/Russia from 200 to 70 Ma, SW Gondwana from 220 to 145 Ma, western North America from 90 to 0 Ma, or Mexico from 16 to 0 Ma.

The effect of fault systems on volcanic activity: Insights from the subduction-related, Quaternary Villamaría-Termales monogenetic volcanic field in Colombia

Structural control of volcanic activity is a topic of great significance around volcanic fields, mostly associated with risk management near cities. Structural geology provides valuable information for understanding the magmatic processes associated with the rise of magma and the presence of volcanoes. The Villamaría-Termales Monogenetic Volcanic Field (VTMVF) is a group of Quaternary monogenetic volcanoes settled in an active fault system, which allows us to propose the role that these faults play in the volcanic activity. The field is located near the city of Manizales (∼475.000 inhabitants), Colombia, on an active fault system at the western flank of the Cordillera Central in the northern Andes. The VTMVF is characterized by andesitic lava domes and flows, which individually reach volumes of up to 2.5 km3. This work uses 1) geometry and kinematics of the faults that affect the VTMVF to define the structural features associated with the emplacement of the volcanoes, and 2) new and published ages to evaluate periods of volcanic activity. Three trends of fault systems associated with the location of the volcanoes were identified: 1) NW-SE (Villamaría-Termales), 2) NE-SW (Sancancio, El Perrillo, Santa Rosa and Palestina), and 3) N-S to NNE-SSW (San Jerónimo and Samaná-sur). The fault kinematics are dominantly normal, with dextral (NE) and sinistral (NW) movements. Analysis of ages shows that the field has temporally evolved since 2 Ma in different time intervals (2.0–1.2 Ma, 0.18–0.045 Ma, and 0.045 Ma – Present). This supports the presence of different emplacement mechanisms related to both the movement in the strike of some faults and the intersection between faults. The pauses of volcanic activity could coincide with the absence of structural conditions (interseismic cycles for faults, where the sealing of the faults is generated) to facilitate the rise of magma; this is related to temporary compressive conditions. Despite the apparent structural controls, there is no clear spatial or temporal pattern of volcano distribution within the field. There is evidence of seismic activity in the area. Thus, the future formation of dilatating zones that allow the magma to rise and the emplacement of new monogenetic volcanoes is feasible not only in the area defined for the volcanic field but also in the continuation of the fault lines around it.

Zircon U–Pb ages and O–Hf isotopes of Quaternary trachytes from the East Sea: Implications for the genesis of low-δ18O magmas

Quaternary intraplate magmatism formed several volcanic islands and seamounts, including Dokdo (DD), Ulleungdo (UD), Simheungtack (ST), Anyongbok, and Isabu in the southwest of the East Sea back-arc basin. In this study, we present whole-rock geochemical, zircon U–Pb age, and in situ O–Hf isotope data for the submerged volcanic rocks from DD, UD, and ST to provide new insights into the eruption timing of these volcanoes and constrain the magma evolution processes. All samples used in this study were trachytes and exhibited ferroan, alkalic, and metaluminous to weakly peraluminous characteristics. They showed light rare earth element (REE)-enriched patterns with (La/Yb)N ratios of 25.3–31.7 and mostly negative Eu anomalies in a chondrite-normalized REE plot. In addition, they were enriched in large-ion lithophile elements and high field strength elements; they exhibited positive Pb anomalies and strongly negative Ba, Sr, P, and Ti anomalies. The zircons yielded a weighted-mean 206Pb/238U age of 2.61, 0.348–0.704, and 2.76–2.94 Ma for the DD, UD, and ST trachytes, respectively. All zircons exhibited lower δ18O values than normal depleted mantle values, regardless of the crystallization age and spatial distribution of volcanoes. The δ18O values showed no correlation with U contents or Th/U ratios, indicating that the low δ18O signatures were of primary magmatic origin. The Hf isotopic compositions of the zircons were relatively heterogeneous but predominately characterized by positive εHf values. Binary O–Hf mixing modeling revealed that low-δ18O rocks with positive εHf values from the UD and ST volcanoes were derived from a hybrid source of recycled juvenile crustal materials with low-δ18O and positive εHf signatures and an enriched mantle source with normal δ18O and negative εHf values. The juvenile oceanic crust in the source was likely metasomatized by seawater at high temperatures prior to melting. In contrast, the felsic magma that formed the DD volcanoes may have assimilated with regional basement rocks (Triassic–Jurassic granitoids), resulting in increased δ18O values and decreased εHf values relative to those of the UD and ST volcanoes. Our study highlights the significant contribution of recycled oceanic crust materials to the generation of the Quaternary magmas.

Tectonically-determined distribution of monogenetic volcanoes in a compressive tectonic regime: An example from the Pannonian continental back-arc system (Central Europe)

This paper presents the results from a geographic information systems (GIS) workflow, which was used to analyze the spatial distribution and temporal evolution of volcanoes in the Mio-Pleistocene monogenetic Bakony-Balaton Highland Volcanic Field (BBHVF), located in the Pannonian Basin, Hungary. Volcanism occurred during the tectonic inversion in a back-arc setting and a compressive/transpressive tectonic regime on the hottest and thinnest lithosphere of continental Europe. The main goal of this study is to clarify the effect of the pre-existing structure of the upper lithosphere in the distribution of the volcanic centers across the volcanic field using an innovative GIS methodology. Orientation of the volcanic field was compared to the orientation of the faults in the BBHVF, and in its larger vicinity, which resulted in correspondence, suggesting the dominance of the SW-NE direction. The directions of the volcanic lineaments fit well to the two main fault directions. The fault-volcano proximity analysis suggests that the fault plane of a thrust fault was an important structural feature during the lifespan of the volcanism. All results suggest that the fault plane of a regionally significant Cretaceous thrust fault (Litér Fault) might have served as a temporary pathway for the ascending magma, whereby (similarly to other, smaller faults) redirecting the magmas causing clustering of the volcanoes. This highlights the importance of major upper crustal structural heterogeneities for magma transport in a compressive tectonic system, especially in the case of active, monogenetic volcanic fields from a volcanic hazard perspective. The present GIS workflow can be effective in analyzing the spatial patterns of the volcanism and its connection with crustal structures at monogenetic volcanic fields worldwide.

SPATIAL ANALYSIS OF VOLCANIC ASH DISTRIBUTION DUE TO VOLCANIC ERUPTION IN JAVA ISLAND

Abstract. Indonesia is located on the Ring of Fire with the most geologically active than any other countries, which makes it vulnerable due to the massive earthquakes and volcanic eruptions. Java Island has the most active volcano with high risks such as human risk and infrastructure from volcanic ash because of volcanic eruptions. The availability of the map of potential volcanic hazards is important to help mitigate the risk caused by volcanic eruptions. However, to the best of the author's knowledge, the distribution of volcanic ash has never been assessed in detail in the disaster-prone hazard map published by the Centre for Volcanology and Geological Hazard Mitigation (CVGHM), Indonesia. This research reported the potential distribution of volcanic ash due to volcanic eruptions in the future in Java island. Following the principles of Probabilistic Hazard Assessment and TephraProb software, the modeling of volcanic ash potential was performed using various parameters such as historical data, eruption source parameter, total grain-size distribution, tephra2 parameter, and the wind speed around the volcanoes as an input. The map shows the distribution of volcanic ash based on the volcanic ash accumulation (kg/m2) and the volcanic ash hazard map is classified into three classes. There are 19 models of volcanic ash distribution with various probabilities of exceedance based on 19 A-type volcanoes on Java Island. This volcano's distribution of volcanic ash tends to the southwest as the wind speed and direction.

MORPHOLOGY OF THE RELIEF OF THE INTRAGLACIAL PALEOVOLCANO DERBY-TAIGA AND THE ADJACENT PART OF THE AZASS PLATEAU (TODZHA BASIN, NORTH-EASTERN TUVA)<a href="#FN1"><sup>1</sup></a>

The Azass Plateau in the Altai-Sayan mountain region is the only known territory in the continental Eurasia know for distribution of intraglacial volcanoes formed by the interaction of erupting lava with ice and melt waters. The orographic factor in the Todzha Basin caused the development of thick shield glaciers covering the area of approximately 13 000 km2 during cold epochs.The variety of geomorphological units reflecting the history of neotectonic evolution, volcanism and Quarternary glaciations creates a unique opportunity to perform paleogeographic reconstructions. The geomorphological map is constructed based on the selection of genetically homogeneous surfaces. Morphometrical indicators, paragenesis and time series were obtained for the later. A special attention was paid to the relief of intraglacial volcanoes and traces of glaciations of different ages.The lower level of intraglacial volcanoes formed in the second half of the Late Pleistocene was subdivided into three levels. These volcanoes formed under a few hundreds of meters of ice. The glacial-exaration genesis of microrelief under the influence of the inland ice was established as appose to the previously accepted water-glacial (catafluvial) genesis. The age of the upper slopes of volcanoes (except the Derbi-Taiga volcano) is the Late Pleistocene. Consequently, glacial valleys and kars complicating them are rejuvenated .The study of the rockfall bodies triggered by an earthquake and rockfalls rupture surfaces in glacial valleys of the Derbi-Taiga mountain massif and their comparison with the traces of the Chuya earthquake (2003) allowed to estimate the Ms = 7.5 magnitude of the Holocene earthquake that caused them.Presented results of the geomorphological investigation contradict the paleogeographic reconstructions performed earlier on the basis of absolute dating.

Asthenospheric Flow From East Asia to the Philippine Sea Plate Revealed by Rj‐MCMC Inversion of Surface Waves

AbstractThe Pacific and Philippine Sea Plate subductions have resulted in and controlled the development of a typical trench‐arc‐back‐arc system in NE Asia since the Cenozoic. The formation of widely distributed intraplate volcanoes and the dynamic pattern of the entire region are still debated. Here we constructed a three‐dimensional anisotropic S‐wave velocity model of NE Asia by inverting Rayleigh wave dispersion using a modified reversible‐jump Markov Chain Monte Carlo (rj‐MCMC) algorithm. The resulting model revealed a localized mantle upwelling beneath intraplate volcanoes in NE Asia and an ongoing lithospheric downwelling beneath the central Korean Peninsula. This suggests vigorous asthenosphere and lithosphere interactions, which is likely to control the spatial distribution of Cenozoic volcanoes. The fast directions show clockwise rotation beneath NE Asia, which eventually points to the Nankai Trough. This observation is broadly consistent with shear wave splitting and suggests the presence of mantle flow from East China to the Philippine Sea Plate. The slab window beneath the Nankai Trough within the Philippine Sea Plate subduction system may accommodate the mantle flow from East China. Our study indicates that the interaction of the Philippine, Pacific Sea Plates, and Eurasian Plates plays an essential role in controlling the mantle flow and intraplate volcanism of NE Asia.

The complexities of assessing volcanic hazards along the Cameroon Volcanic Line using spatial distribution of monogenetic volcanoes

Volcanic eruptions represent hazards for local communities and infrastructure. Monogenetic volcanoes (usually) erupt only once, and then volcanic activity moves to another location, making quantitative assessment of eruptive hazards challenging. Spatio-temporal patterns in the occurrence of these eruptions may provide valuable information on locations more likely to host future eruptions within monogenetic volcanic fields. While the eruption histories of many stratovolcanoes along the Cameroon Volcanic Line (CVL) are relatively well studied, only fragmentary data exist on the distribution and timing of this region's extensive monogenetic volcanism (scoria cones, tuff rings, maars). Here, we present for the first time a catalog of monogenetic vents on the CVL. These were identified by their characteristic morphologies using field knowledge, the global SRTM Digital Elevation Model (30 m resolution), and satellite imagery. More than ~1100 scoria cones and 50 maars/tuff rings were identified and divided into eight monogenetic volcanic fields based on the visual assessment of clustering and geological information. Spatial analyses show a large range of areal densities between the volcanic fields from >0.2 km−2 to 0.02 km−2 from the southwest towards the northeast. This finding is in general agreement with previous observations, indicating closely spaced and smaller edifices typical of fissure-fed eruptions on the flanks of Bioko and Mt. Cameroon in the southwest, and a more focused plumbing system resulting in larger edifices of lower spatial density towards the northeast. Spatial patterns were smoothed via kernel density estimates (KDE) using the Summed Asymptotic Mean Squared Error (SAMSE) bandwidth estimator, the results of which may provide an uncertainty range for a first-order hazard assessment of vent opening probability along the CVL. Due to the scarce chronological data and the complex structural controls across the region, it was not possible to estimate the number of vents formed during the same eruptive events. Similarly, the percentage of hidden (buried, eroded) vents could not be assessed with any acceptable statistical certainty. Furthermore, the impact of different approaches (convex hull, minimum area rectangle and ellipse, KDE isopaches) to define volcanic field boundaries on the spatial distribution of vents was tested. While the KDE boundary definition appears to reflect the structure of a monogenetic volcanic field better than other approaches, no ideal boundary definition was found. Finally, the dimension of scoria cones (approximated by their basal diameters) across the CVL was contrasted to the specific geodynamic setting. This region presents a complex problem for volcanic hazard analysis that cannot be solved through basic statistical methods and, thus, provides a potential testbed for novel, multi-disciplinary approaches.

Relationships between Payenia volcanism and deep-seated structural controls: Insights from geophysical methods at Nevado volcanic field, Mendoza, Argentina

The Nevado Volcanic Field (NVF), in southern Mendoza foothills, is part of the Payenia Volcanic Province, a large Quaternary retro-arc volcanic area composed principally of basaltic lava flows and monogenetic volcanoes. Monogenetic volcanism location, distribution and evolution are extremely sensitive to previous rheological discontinuities or faults affecting their basement. With the aim of exploring the subsurface configuration and contributing to a better understanding of this volcanism, we analysed and interpreted aeromagnetic and gravity datasets in addition to structural and volcanic alignments information. Our results show that location of volcanism would have been mainly controlled by NW-SE trending structures. These structures would extend at least to middle crust levels. On the other hand, a secondary control might be related to crustal domains with different densities, which could have affected magma propagation to the surface, hence, controlling the spatio-temporal distribution of volcanoes. The complex interplay between these factors would be responsible for the distribution of volcanic centres. Finally, we discuss the implications of these controls concerning the tectonic stress regime contemporaneous with volcanic activity.

Tectonic controls on geomorphology and spatial distribution of monogenetic volcanoes in the Central Southern Volcanic Zone of the Andes (Argentina)

Monogenetic volcanoes are among the most common volcanic landforms on Earth. The morphology and distribution of small volcanoes can provide important information about eruption dynamics and tectonics. The Southern Volcanic Zone of the Andes (CSVZ) comprises one of the most active magmatic regions on Earth. Characterized by the presence of polygenetic volcanoes and calderas in a complex tectonic setting, this region also hosts hundreds of small, back-arc monogenetic volcanoes. In this contribution, we apply a Geographic Information System (GIS) that combines imagery data and digital elevation models to establish the first comprehensive dataset of monogenetic volcanoes in the CSVZ (38° to 40° S), exploring their eruption dynamics and relationship to tectonic and structural processes. Combining spatial analysis and geomorphological observations, we identify the presence of 335 monogenetic volcanoes distributed into nine clusters, now grouped in the Zapala Volcanic Field (ZVF). The ZVF is marked by the predominance of cinder cones (80%) followed by phreatomagmatic volcanoes (20%), suggesting some influence of external water in the eruption dynamics. Generally, monogenetic vents present a clear association with local and regional lineaments, suggesting a strong structural control on the occurrence of the monogenetic deposits in the ZVF. The higher vent densities are observed in the southern Loncopué Though, an important extensional feature related to tearing of the subducted Nazca plate underneath the South American Plate. Morphometric parameters of cinder cones indicate variable stress orientations in the CSVZ that possibly results from the oblique tectonics in the region. From north to south, the maximum principal stress rotates from NE-SW to E-W and becomes progressively less constrained as it distances from the current magmatic arc. Based on the relative ages, we map the evolution of monogenetic volcanism through time. Our results suggest a waning in the monogenetic activity in ZVF over time. When compared to monogenetic fields in the Central Andes, the ZVF is marked by higher vent densities and number phreatomagmatic landforms, with the absence of lava domes. This ultimately reflects the contrasting crustal structure and climate conditions of these two regions.

The Role of Temperature in the Along‐Margin Distribution of Volcanism and Seismicity in Subduction Zones: Insights From 3‐D Thermomechanical Modeling of the Central Andean Margin

AbstractThe distribution of volcanic and seismogenic zones is segmented along the trench‐parallel direction in the Central Andes, and factors controlling their clustering are not fully understood. Here we present a 3‐D thermomechanical model of the subduction zone at 18°–26°S to examine the role that temperature and mantle flow play in the distribution of active volcanoes and seismicity. We applied a steady state approach in which solid‐state flow is driven by a kinematically prescribed slab with realistic geometry (including changes along the Bolivian Orocline) and using a 3‐D model of the continental crust thickness. The obtained temperature distribution is consistent with proxies for isotherms derived from independent geophysical data, except below the Eastern Cordillera at 21°–23°S. The computed mantle flow pattern reveals the presence of along‐margin dynamic pressure gradients. This 3‐D preferential flow results in mantle temperatures of 1200–1400°C at 80–100 km depth below the arc, with comparatively higher temperatures at ∼22°–25°S. The obtained along‐margin variations in temperature and in estimated melt velocity suggest that the subarc mantle south of 22°S exhibits more favorable conditions for generation and upward migration of partial melts. This segment coincides with the higher concentration of active arc volcanoes and the presence of the Altiplano‐Puna Volcanic Complex in the backarc. Intermediate‐depth seismicity concentrates roughly below where the slab top is at 400–800°C, suggesting that temperature exerts some control on the first‐order distribution of intraslab seismicity. However, most intraslab seismicity occur at pressure‐temperature conditions which are outside of the stability field expected for key dehydration reactions in slabs.

Controls on sediment distribution in a volcanically-affected basin: insights from the Ethiopian Flood Basalt Province

Abstract This study provides a comprehensive examination of the Oligocene–Miocene Ethiopian Flood Basalt Province (EFBP) within the Blue Nile (Abay) Basin (BNB), Ethiopia. Extensive logging through 29 new sections has enabled an updated stratigraphic account of the BNB to be elucidated and reveals the significance of intravolcanic sedimentary systems within the EFBP. Five sub- and intra-volcanic surfaces were modelled using spot heights to generate isopach maps that were used to constrain the thickness variations within the stratigraphy. Additionally, lineaments, Strahler stream segments and volcanic cones were mapped out from digital elevation models (SRTM DEM) and satellite data (ASTER and LANDSAT 8 imagery). These data were used in conjunction with the isopach maps to better understand the basinal controls on the distribution of intravolcanic sedimentary systems within the BNB. The study reveals how NNE and ESE/SE structural trends have influenced the distribution of volcanoes within the basin, which has in turn disrupted the distribution and lithofacies architecture of the volcanic sequences. The presence of intrabasinal ridges parallel to the major structural trends are also revealed, which formed relatively short-lived drainage divides. The implications of these intrabasinal highs on the composition and the reservoir potential of intravolcanic sedimentary successions are discussed.

Morphology and distribution of monogenetic volcanoes in Los Tuxtlas Volcanic Field, Veracruz, Mexico: implications for hazard assessment

Morphology and distribution of monogenetic volcanoes in Los Tuxtlas Volcanic Field, Veracruz, Mexico: implications for hazard assessment

Morphological and multivariate statistical analysis of quaternary monogenetic vents in the Central Anatolian Volcanic Province (Turkey): Implications for the volcano-tectonic evolution

The interaction and competition between magmatic and tectonic processes mostly control the spatial distribution and morphology of monogenetic volcanoes. The Central Anatolian Volcanic Province, situated in a strike-slip environment, provides a remarkable opportunity to understand this relationship. We defined six monogenetic clusters and analyzed 540 Quaternary monogenetic volcanoes in terms of morphological and spatial characteristics. There is no distinct correlation among the morphological parameters of scoria cones or lava domes, possibly owing to the various factors and the sporadic nature of magmatic activity in the region. Our detailed multivariate statistical and vent alignment analyses together with several implications in the literature reveal that the CAVP is a tectonically-controlled intraplate volcanic field, which is mostly driven by regional deformations. The presence of both clustered and non-clustered vent distributions and the petrological characteristics of the volcanics within the region indicates that the dikes are derived directly by the pre-existing melt-bearing heterogeneous mantle (i.e., Eğrikuyu monogenetic field) or the independent and short-lived shallow or deep crustal magma reservoirs (i.e., Nevşehir-Acıgöl volcanic field). The local changes in the stress regimes and crustal lithology result in variations of field shape, spatial vent distribution, and vent alignments throughout the region. The triggering mechanisms for the initiation of the Quaternary volcanism in the region can be the lithospheric-scale Central Anatolian fault zone, here considered as an immature rift zone where Erciyes volcanic field is developed and behaves as a possible magmatic transfer zone. Tuz Gölü fault zone as a western border of the so-called rift basin in the region is mostly responsible for the crustal propagation of magma, and the kinematic changes along this fault zone (i.e., strike-slip to normal) mostly shaped the spatial vent distributions and alignments of the clusters in its close proximity (e.g., Hasandağ-Keçiboyduran volcanic field).

Morphometric classification and spatial distribution of Philippine volcanoes

The Philippine Island Arc has a large number of volcanoes with diverse morphologies, making it an ideal location to study the factors controlling the morphology and spatial distribution of island arc volcanoes. We have identified 731 volcanic edifices using the SRTM 30 m digital elevation model, and computed their quantitative morphology using the MORVOLC algorithm. Hierarchical classification by principal component (PC) analysis distinguishes four volcano types: small flat cones, small steep cones, large cones, and massifs, with mean volumes of 0.2 km3 (<6.2 km3), 0.4 km3 (<9 km3), 29 km3 (0.15–178 km3), 267 km3 (76–675 km3), mean heights of 125 m (16–721 m), 260 m (53–971 m), 842 m (59–2313 m), 1533 m (1012–2175 m), and mean slopes of 13° (3–21°), 22° (14–37°), 15° (3–28°), 15° (11–22°), respectively. This classification is based mainly on their size and irregularity (PC1) and steepness (mean slope and height/basal width ratio; PC2), and to a lesser extent on the size of the summit region and edifice truncation (PC3) and edifice elongation (PC4). These morphological volcano classes represent stages along an evolutionary trend. The small flat cones are mostly monogenetic, whereas the small steep cone class represents an early growth stage. Some can develop into large polygenetic cones while a few can further grow laterally into massifs, both of which are preferentially found on thickened crust. There is a trend towards more silicic compositions from small to large cones, perhaps due to larger edifice loads preventing mafic dykes from reaching the surface. The distribution and alignment of the edifices within volcanic fields seems to be influenced by both regional and local stress fields and pre-existing structures.

A 2020 Observational Perspective of Io

Jupiter's Galilean satellite Io is one of the most remarkable objects in our Solar System. The tidal heating Io undergoes through its orbital resonance with Europa and Ganymede has resulted in a body rich in active silicate volcanism. Over the past decades, Io has been observed from ground-based and Earth-orbiting telescopes and by several spacecraft. In this review we summarize the progress made toward our understanding of the physical and chemical processes related to Io and its environment since the Galileo era. Io science has been revolutionized by the use of adaptive optics techniques on large, 8- to 10-m telescopes. The resultant ever-increasing database, mapping the size, style, and spatial distribution of Io's diverse volcanoes, has improved our understanding of Io's interior structure, its likely composition, and the tidal heating process. Additionally, new observations of Io's atmosphere obtained with these large optical/infrared telescopes and the Atacama Large Millimeter/submillimeter Array reveal the presence of volcanic plumes, the (at times) near-collapse of Io's atmosphere during eclipse, and the interactions of plumes with the sublimation atmosphere. ▪ Extensive new data sets of Io at ultraviolet, mid- to near-infrared, and radio wavelengths have been gathered since the Galileo era. ▪ New data and models inform us about tidal heating, surface properties, and magma composition across Io—although key questions remain. ▪ Atmospheric observations indicate a dominant sublimation-supported component and reinforce the presence of stealth volcanism. ▪ Observations of volcanic plumes show high gas velocities (up to ∼1 km/s) and their effect on Io's atmosphere.