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

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

What Do We Know About Calderas?

The International Association of Volcanology and Chemistry of the Earth's Interior (IAVCEI) Commission on Collapse Calderas organized its fourth workshop in the Vulsini Calderas District, Italy (http://www.gvb‐csic.es/CCC.htm). Vulsini includes the Bolsena and Latera calderas, formed in the past 0.6 million years. It is a famous type locality where fundamental concepts concerning caldera collapse and eruptive dynamics have been proposed

Miocene sedimentation, volcanism and deformation in the Eastern Cordillera (24°30′ S, NW Argentina): Tracking the evolution of the foreland basin of the Central Andes

Understanding the relationships between sedimentation, tectonics and magmatism is crucial todefining the evolution of orogens and convergent plate boundaries. Here, we consider the lithostratigraphy, clastic provenance, syndepositional deformation and volcanism of the Almagro-El Toro basin of  W Argentina (24¡ã30¡ä S, 65¡ã50¡ä W), which experienced eruptive and depositional episodes between 14.3 and 6.4  a. Our aims were to elucidate the spatial and temporal record of the onset and style of the shortening and exhumation of the Eastern Cordillera in the frame of the Miocene evolution of the Central Andes foreland basin. The volcano-sedimentary sequence of the Almagro-El Toro basin consists of lower red floodplain sandstones and siltstones, medial non-volcanogenic conglomerates with localised volcanic centres and upper volcanogenic coarse conglomerates and breccia. Coarse, gravity flow-dominated (debris-flow and sheet-flow) alluvial fan systems developed proximal to the source area in the upper and medial sequence. Growing frontal and intrabasinal structures suggest that the Almagro-El Toro portion of the foreland basin accumulated on top of the eastward-propagating active thrust front of the Eastern Cordillera. Synorogenic deposits indicate that the shortening of the foreland deposits was occurring by 11.1 Ma, but conglomerates derived from the erosion of western sources suggest that the uplift and erosion of this portion of the Eastern Cordillera has occurred since ca.12.5 Ma. An unroofing reconstruction suggests that 6.5 km of rocks were exhumed. A tectono-sedimentary model of an episodically evolving thick-skinned foreland basin is proposed. In this frame, the NW-trending, transtensive Calama¨COlacapato¨CEl Toro (COT) structures interacted with the orogen, influencing the deposition and deformation of synorogenic conglomerates, the location of volcanic centres and the differential tilt and exhumation of the foreland.¡ã30¡ä S, 65¡ã50¡ä W), which experienced eruptive and depositional episodes between 14.3 and 6.4  a. Our aims were to elucidate the spatial and temporal record of the onset and style of the shortening and exhumation of the Eastern Cordillera in the frame of the Miocene evolution of the Central Andes foreland basin. The volcano-sedimentary sequence of the Almagro-El Toro basin consists of lower red floodplain sandstones and siltstones, medial non-volcanogenic conglomerates with localised volcanic centres and upper volcanogenic coarse conglomerates and breccia. Coarse, gravity flow-dominated (debris-flow and sheet-flow) alluvial fan systems developed proximal to the source area in the upper and medial sequence. Growing frontal and intrabasinal structures suggest that the Almagro-El Toro portion of the foreland basin accumulated on top of the eastward-propagating active thrust front of the Eastern Cordillera. Synorogenic deposits indicate that the shortening of the foreland deposits was occurring by 11.1 Ma, but conglomerates derived from the erosion of western sources suggest that the uplift and erosion of this portion of the Eastern Cordillera has occurred since ca.12.5 Ma. An unroofing reconstruction suggests that 6.5 km of rocks were exhumed. A tectono-sedimentary model of an episodically evolving thick-skinned foreland basin is proposed. In this frame, the NW-trending, transtensive Calama¨COlacapato¨CEl Toro (COT) structures interacted with the orogen, influencing the deposition and deformation of synorogenic conglomerates, the location of volcanic centres and the differential tilt and exhumation of the foreland.Fil: Vezzoli, Luigina. Università Degli Studi Dell'insubria; ItaliaFil: Acocella, Valerio. Università Roma Tre III; ItaliaFil: Omarini, Ricardo Hector. Universidad Nacional de Salta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Mazzuoli, Roberto. Università degli Studi di Pisa; Itali

Special issue "Advancement of our knowledge on Aso volcano: current activity and background

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Kinetic energy of solid neon by Monte Carlo with improved Trotter- and finite-size extrapolation

The kinetic energy of solid neon is calculated by a path-integral Monte Carlo approach with a refined Trotter- and finite-size extrapolation. These accurate data present significant quantum effects up to temperature T=20 K. They confirm previous simulations and are consistent with recent experiments.Comment: Text and figures revised for minor corrections (4 pages, 3 figures included by psfig

Benzene (update)

prepared by Syracuse Research Corporation under contract no. 200-2004-09793 ; prepared for U.S. Department of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry."August 2007.""A Toxicological Profile for Benzene, Draft for Public Comment was released in August 2005. This edition supersedes any previously released draft or final profile"--P. iii.Chemical managers/authors: Sharon Wilbur, Sam Keith, Obaid Faroon, ATSDR, Division of Toxicology and Environmental Medicine, Atlanta, GA; David Wohlers, Julie Stickney,.Sari Paikoff,.Gary Diamond, Antonio Quin\ucc\u192ones-Rivera,.Syracuse Research Corporation, North Syracuse, NY --p. ix.Also available via the World Wide Web.Includes bibliographical references (p. 313-376) and index

Review of multiple hazards in volcanic islands to enable the management of long-term risks: the cases of Ischia and Vulcano, Italy

The management of long-term volcanic risks represents a challenge that requires a close cooperation between science and decision-making. This is particularly crucial in volcanic islands, which are characterized by multiple hazards concentrated in a relatively small environment, often associated with a large seasonality of exposure due to tourism. The scientific challenges are mainly the quantification and the characterization of the interactions among the multiple hazardous phenomena that may occur during the different “states of thevolcano” (quiescence, unrest, eruption) and the definition of robust methods to forecast the transition between these states. For these topics, the emerging scientific knowledge is often rather limited and uncertain and, also in case it was well constrained, difficult to communicate to decision makers due to its intrinsic complexity. On the other side, the challenge for decision making is to assimilate this uncertain knowledgeand translate it into actions. Here, we discuss the experience gained in two working groups (WGs) in charge of reviewing the state of knowledge about volcanic hazards for the Italian volcanic islands of Ischia and Vulcano to build the scientific ground for subsequent decision making. These WGs, formed within the agreement between INGV and the Italian Civil Protection Department, involved about 20 researchers from INGV and Universities, as well as representatives of the Italian Civil Protection, to facilitate the reciprocal understanding and to address the work toward useful results for decision making. The WGs reviewed all the potential volcanic hazards for Ischia and Vulcano based on literature, results of previous projects, as well as ad hoc audits of other experts on specific topics, and organized a workshop to present the results and receive feedbacks from the extended scientific community

A roadmap for amphibious drilling at the Campi Flegrei caldera: insights from a MagellanPlus workshop

Large calderas are among the Earth's major volcanic features. They are associated with large magma reservoirs and elevated geothermal gradients. Caldera-forming eruptions result from the withdrawal and collapse of the magma chambers and produce large-volume pyroclastic deposits and later-stage deformation related to post-caldera resurgence and volcanism. Unrest episodes are not always followed by an eruption; however, every eruption is preceded by unrest. The Campi Flegrei caldera (CFc), located along the eastern Tyrrhenian coastline in southern Italy, is close to the densely populated area of Naples. It is one of the most dangerous volcanoes on Earth and represents a key example of an active, resurgent caldera. It has been traditionally interpreted as a nested caldera formed by collapses during the 100–200 km3 Campanian Ignimbrite (CI) eruption at ∼39 ka and the 40 km3 eruption of the Neapolitan Yellow Tuff (NYT) at ∼15 ka. Recent studies have suggested that the CI may instead have been fed by a fissure eruption from the Campanian Plain, north of Campi Flegrei. A MagellanPlus workshop was held in Naples, Italy, on 25–28 February 2017 to explore the potential of the CFc as target for an amphibious drilling project within the International Ocean Discovery Program (IODP) and the International Continental Drilling Program (ICDP). It was agreed that Campi Flegrei is an ideal site to investigate the mechanisms of caldera formation and associated post-caldera dynamics and to analyze the still poorly understood interplay between hydrothermal and magmatic processes. A coordinated onshore–offshore drilling strategy has been developed to reconstruct the structure and evolution of Campi Flegrei and to investigate volcanic precursors by examining (a) the succession of volcanic and hydrothermal products and related processes, (b) the inner structure of the caldera resurgence, (c) the physical, chemical, and biological characteristics of the hydrothermal system and offshore sediments, and (d) the geological expression of the phreatic and hydromagmatic eruptions, hydrothermal degassing, sedimentary structures, and other records of these phenomena. The deployment of a multiparametric in situ monitoring system at depth will enable near-real-time tracking of changes in the magma reservoir and hydrothermal system

Coupling volcanism and tectonics along divergent boundaries: collapsed rifts from Central Afar, Ethiopia

Magma along divergent plate boundaries is erupted from fissures or vents from central volcanoes, with limited impact on rift architecture. Here I summarize the geological and structural features accompanying the eruption of part of a km-thick volcanic sequence (“Stratoids”) along the Red Sea divergent boundary in Central Afar, in the area of Tendaho and Dobi grabens. More than 4700 km3/Ma (per 100 km of rift length) of magma have been produced by repeated fissure eruptions from within Tendaho Graben. The graben sides show distinctive structural features, as steep topographic gradients, coinciding with inward tilted blocks forming dominoes coeval to the emplacement of the km-thick volcanic sequence. Similar features are observed also in the Dobi Graben. This allows proposing an original mechanism, where the distinctive structure of the grabens results from the collapse at the surface induced by magma withdrawal during the emplacement of the volcanic sequence. This portion of Afar shows how rift architecture is shaped by voluminous fissure eruptions, forming collapsed rifts. These occur in continental domains, during the break-up stage (Central Afar) and in oceanic domains, where rifts narrow (East Pacific Rise). Collapsed rifts represent an end-member type of volcano-tectonic activity, where the width of the erupting reservoir balances that of the active rift zone. Along divergent boundaries, the width of the reservoir influences the style of surface deformation: a progressively higher ratio of the width of the reservoir emptied (Re) to that of the active rift zone (Ri) generates, in sequence, axial grabens, calderas and collapsed rifts