Introductory Chapter: Updates in Volcanology – From Volcano Modeling to Volcano Geology

The book “Updates in Volcanology: From volcano modelling to volcano geology” is composed of 13 book chapters provided by authors from a great variety of disciplines. Each of the book chapter genuinely reflects the diversity of volcanological researches in recent years and documents new look at geological problems associated with volcanism and volcanic hazard research. The chapters from this book represent perfectly the current trends in volcanology as a merging research directions from geophysical aspects of volcanology and its traditional field-based methods. The book chapters have been grouped into three sections.

geochemical processes interact and create a complex 3D array of solidified melts that can then be traced in the geological record as igneous rocks.
Following the detailed summary of the melt generation and migration toward the surface, the next chapter takes the reader to the "surface" and provides a methodological summary on the power of photogrammetric surveys in volcanology. This chapter not only provides an exciting and new read on a traditional method to define volcanic morphology and their temporal changes during volcanic eruptions but it also takes the reader to a very active volcanic zone-Kamchatka-that produced several of the most spectacular volcanic eruptions in the last centuries including the Bezymianny 1955 and other [8,9], Great Tolbachik 1975 [10-13] and recent 2012 events [14,15] (Figure 1) (Figure 2) volcanoes ongoing eruptions. Many of these eruptions not only provided new insight to volcanic eruption processes but also gave new conceptual models for gold recycling beneath volcanoes [20] or let us discover new minerals such as the tolbachite (CuCl 2 ) [21] and other unique minerals [22] or special rock names such as avachites a high-magnesian basalt group documented from the Avachinsky volcano [23]. This chapter looks back 100 years of research history and provides some forgotten images and documents from an area largely unknown for the majority of volcanologists. The chapter through its critical review and global comparison also provides a way forward for the development of the photogrammetric method in volcanology. Linked to the previous chapter, the third chapter provides a critical review with some original data and research about the role of volcano gravimetry. Volcano gravimetry has developed dramatically in recent years and became a fundamental tool to understand activity changes inside a volcano and hence use collected in situ or near real-time data to estimate volcanic alert status in active volcanoes [24][25][26][27][28][29]. Gravimetry studies also been used to detect various volcanic structures such as maar-diatreme volcanoes and establish the geological origin of sediment field terrestrial basins, which indeed not as simple process as we might think [30][31][32][33]. Similarly, gravimetry has been applied successfully to describe the internal architecture of large volcanoes [34] as well as relatively small-scale features as cavities in lava flows [35]. This chapter provides an easy to understand review of the science behind gravimetry studies then provides an evaluation for the future of gravimetry research on volcanoes. The fourth chapter takes the reader to Kyushu in Japan and provides a state-of-art research report with a high-value review of the methods applied to understand the gravity gradient tensor in active volcanic regions in southern Japan. Southern Japan is a home of several post-Pliocene calderas that define the landscape today and the style of expected volcanism in the region [36]. The Kagoshima Bay and its surrounding is in particular one of the region where the highest frequency of silicic caldera-forming eruptions is known on Earth that produced multiple large (10 km<) across calderas and associated ignimbrite and silicic pyroclastic tephra sheets [37]. The large number of volcanoes in these regions alongside with the thick deposits made difficult to see the internal structure of many of these complex volcanoes and their structural relationship to the regional and volcano-tectonic structures; hence, geophysical methods are useful to provide data. This book chapter provides an introduction to the applicability of special gravity gradiometry survey with a new technique to define gravity gradient tensors. The chapter provides clear example to demonstrate that this method capable to locate structural elements such as caldera walls as it has been tested across the Aso caldera [38] hence offer some new avenue to explore for others in other complex volcanic terrains such as the caldera-pitted North Island in New Zealand [39,40].
The fifth and closing chapter of this section of the book provides a summary of large-scale experiments to understand the source conditions and controlling parameters of explosive eruptions. This chapter is a valuable summary of the methods applied for large-scale experiments written by a group of researchers pioneered experimental volcanology through largescale experiments; hence, the reader can get a very genuine view of such researches limitations and extent [41,42]. In addition, the author group is also strongly linked to field-based research on pyroclastic deposits of pyroclastic density currents; therefore, this chapter provides wellestablished ideas and concepts [43]. In general, large-scale experiment to model various types of explosive processes, magma fragmentations, crater formation, and their numerical modeling is probably one of the most dynamic parts of volcanology in recent years [44][45][46][47][48][49][50][51][52][53][54][55][56]. In this chapter, different methodologies for investigating eruptive source conditions and the subsequent evolution of the eruptive plumes are presented. The methodologies range from observational techniques to large-scale experiments and numerical models. The chapter also poses fundamental research questions that can only be answered if we follow the proposed techniques to define the effect of unsteady flow conditions at the source on the eruptive column dynamics and the interaction between a convective plume and wind.
The second section of the book "volcanic eruptions and their impact to the environment" consists of five chapters. Each of these chapters provides various aspects of volcanism from their hazard and consequence perspective. The opening chapter of this section sum up the volcanological information associated with one of the less known volcano that produced one of the largest set of eruptions in the past 10 ka. Baekdusan volcano that is located in the frontier between China and North Korea is a volcano that has a basaltic shield capped by a trachytedominated sequence and a large caldera [57]. This chapter highlights the fact that Baekdusan volcano is an active and very complex volcano as its volcanic seismicity, ground deformation, and volcanic gas geochemistry yields indicate that a magmatic unrest takes place in the period between 2002 and 2006. The geological record and the recent volcano monitoring data suggest that the Mt. Baekdusan is an active volcano [58]; hence, proper volcanic hazard studies are needed to estimate the potential volcanic eruption scenarios a new eruption would follow.
The second chapter in this section takes the reader to Japan where an analysis of the magnitudefrequency distribution of slope failures was studied. The statistical data provided in this chapter are based on many years of research, and this chapter gives a very useful summary to the readers how to apply similar method to their fields. Interestingly, this chapter provides a relatively simple equation for the magnitude-frequency distribution of slope failures for larger than 10 7 m 3 volumes. The chapter concludes that this magnitude-frequency may applicable over several thousands of years of record making possible for future large-scale volcanic failure predictions. It is an alarming conclusion however, that larger than 10 9 m 3 mega collapses can occur in every 1000-2000 years period; hence, such mega events cannot be looked at as a rare events in Japan. Volcanic debris avalanches are common volcanic processes that generate a specific volcanic sedimentary successions and geomorphological disturbances; hence, their study is important [59,60]. Such large-scale failures of volcanic edifices need to be studied in similar way as this chapter demonstrated to be able to provide magnitude-frequency distribution relationships in volcanic terrains prone to collapse.
The third chapter of this section deals with a research area of volcanic aerosol behavior developing dynamically in recent years to provide functioning models to volcanic aerosol effect to radiation in the Arctic. This chapter claims that despite the suspected perturbance of volcanic aerosols to the Arctic radiation balance, we know very little about their radiative impacts in the Arctic. It is also poorly understood partially due to the limited attention, this process has received what the effects of other aerosol types that are often present in the region [61], both natural and anthropogenic [62][63][64]. The link between volcanic events and their potential climatic impact is one of the subjects reach beyond the limits of volcano sciences and commonly connected to social studies, history, and art [65][66][67][68][69]. Research activity to understand volcanic aerosol behavior over the Arctic has also increased in recent years [70][71][72]; hence, this chapter provides a very useful summary of the current state of knowledge. The chapter points out that the Arctic environment is both unique and complicated, and the perturbations caused by volcanic aerosol need to be examined in a regional context. Due to the harsh environment, more data are derived from remote sensing; hence, this chapter provides a comprehensive summary of remotely sensed data collection techniques. The numerous models presented in this chapter show the strengths and shortcomings of volcanic ash transport and dispersion models in general [73][74][75] and calling future targeted research specifically designed for Arctic conditions. Among many, the authors claim that the effect of ash aggregation such as accretionary lapilli formation [76,77] not many cases considered in ash transport and deposition models in spite their huge effect on the potential distribution pattern their deposition can show [78].
The fourth chapter in this section takes a reader to a fairly new research area that studies the link between corrosion effects on various alloys in a volcano-polluted seawater. Corrosion damage in human-built environment caused by volcanic processes can cause significant economic loss especially in marine steel infrastructures such as bridges, wharfs, platforms, and pipeline systems. While understanding the corrosion in general relatively well documented in subaerial conditions such as volcanic ash and acid rain effect on man-made structures [79][80][81]. Similar studies in a subaqueous environment are relatively rare [82]. This chapter provides an interesting overview of the world of corrosion including the description of techniques that can measure their rates. The results of the study of corrosion in volcanic-polluted waters can contribute to understanding of the volcanic hazards and associated risks of such processes that can act on human-built environments.
The final chapter in this section deals with the mineral assemblages recorded in various fumarolic systems across the most famous fumarole fields in Europe. This chapter provides a descriptive overview of the mineral phases recorded from various fumarolic systems focusing on examples from Italy and Greece. Fumarolic systems viewed as important environments where rare elements can concentrate even in economically significant amount [20]. The mineral variations associated with fumarolic systems are great, and such systems often act as harvesting ground to identify previously unknown minerals [10,83]. Fumarolic systems are also viewed as a window to the magmatic system; hence, they commonly studied with an aim to understand the magma behavior provides the heat beneath such systems [84][85][86]. This chapter takes examples from well-known fumarolic systems such as those at Vulcano Island in Italy to raise some awareness among researchers on the significance of fumarolic systems in volcanic regions.
The final, third section of the book consists of three chapters dealing with volcanic geology problems that can be applied to older volcanic successions. The section starts with an exhaustive summary of the recent results on the study of subaqueous explosive and effusive volcanism in the Cabo de Gata region in SE Spain. Subaqueous volcanism in recent years became the center of volcanic researches [87] partially due to the racing to identify reliable evidences of presence of water or ice on extra-terrestrial regions commonly associated with volcanism [88,89] and understand ore-forming processes in volcanic regions located or closely linked to subaqueous environments [90,91]. It is just an addition to the increase of research activity that in the geological record, volcanic rocks are commonly associated with subaqueous sedimentary rocks; hence, there is a need to understand well the limitations of identification of various eruptive environment hence using volcanic rocks for paleoenvironmental (eruptive environment) reconstructions. Identification of peperites [92] for instance became a trademark to contribute to the eruptive environment discussions such as establishing subaqueous versus subaerial conditions [93]. Similarly, new researches on distinguishing explosive versus effusive non-explosive fragmentation of magma to feed large volume of hyaloclastite piles provided useful tools to use these deposits for paleoenvironmental reconstruction of rock units in the geological record [94,95]. As a result of these research activities, a new commission called Commission of Subaqueous Volcanism of the International Association of Volcanology and Chemistry of the Earth's Interior was established in 2016. Cabo de Gata is probably one of the most perfectly exposed regions where the eruptive products (effusive and explosive) of subaqueous volcanism can be accessed along coastal sections [96]. This chapter provides a very detailed summary for the research results of the study of the Cabo de Gata volcanic rocks based on many previous research works [97]. The second chapter in this section addresses a question: how polygenetic are monogenetic volcanoes? This question sounds strange as the two word, monogenetic versus polygenetic are opposing and negating each other. The authors take the reader to a journey to demonstrate the difficulty to define monogenetic volcanism especially if we are looking at volcanic successions preserved in a geological record. Such problem has been addressed recently in many places arguing that in old but partially preserved and eroded successions, the distinction between volcanic rock units formed in a single and short volcanic process can look very similar to those that formed over longer time without significant evidence of erosional surfaces in the rock units. This chapter draws again the attention to view small-volume volcanoes as a system that functions as a source to surface model [98]. In such model, the timing, longevity, and the total eruptive volume of individual eruptive episodes and the total volcanic activity can produce complex volcanic facies architecture composed of multiple eruptive units commonly forming such small-volume volcanoes [99,100]. This chapter explores the volcanic facies architecture of small-volume volcanoes that carry obvious signs of complex eruptive history that commonly can be translated to relatively long eruptive history and an elevated volume of magma involvement [101][102][103]. This chapter is useful to understand the gradual transition of small to large volcanoes, hence to see the link between monogenetic and polygenetic volcanism [104].
The final chapter of this section and the entire book takes the reader to a volcanic region in Inner Mongolia, China, where volcanic rocks help to understand the evolution of the Central Asian Orogenic Belt [105][106][107][108]. While this region is not directly considered as a locality of volcanological studies, its geological history documents significant magmatological processes associated with terrane accretion and associated volcanic processes [109]. The region is also a home of advanced studies of adakite magmas, and hence, it is inferred that magmatism resulted from intermediate to felsic magmas that carry geochemical characteristics indicative for the melt to be sourced by partial melting of the altered basalt that is subducted below volcanic arcs [110]. This chapter also highlights the methods need to be applied to recognize various stages of terrain accretion and petrogenetic processes associated with a complex plate margin process.
The book overall provides a great diversity of subjects relevant to volcanic researches. While the book purely a result of "blue sky" attempt to collect new research outputs reflecting the current trends in volcanic researches, the selection of chapters reflects well the dynamic nature of volcanological researches. The book naturally cannot provide a balanced summary of the current advances in volcanology. Large and dynamically developing segments of current volcanological research are not covered in this book. Reports on the advances of crater formation based on analog experiments [47,50], experimental volcanological studies [76,[111][112][113], lava flow dynamic modeling through experiments and numerical codes [114,115], developing new methods for eruption forecasting especially the eruptions' economic impact [116][117][118][119], experimental and field-based studies of maar-diatreme volcanism [48] or new advances in understanding magma fragmentation, vesiculation, and their internal and external controlling parameters are among many new research fields this book has not provided overviews. Also, recently, IAVCEI has established a new commission called Commission on Volcano Geoheritage and Protected Volcanic Landscape, which is a clear sign