Volcanological Research Research Articles

Improving communication between volcano observatories and volcanic ash advisory centres in Europe—outcomes from a first workshop

AbstractEffective aviation response to atmospheric emissions from volcanic eruptions relies upon timely communication and information exchange. To explore the current and best practices in this area, a workshop was held in February 2019 under the framework of the European H2020 EUROVOLC project (2018–2021). The objective of the workshop was to bring together the volcano observatories (VOs), volcanic ash advisory centres (VAACs), and volcanological research institutes in Europe. The workshop included scientists and operational staff from six of Europe’s VOs (Iceland, Italy, France, Spain, Portugal, and Greece), the London and Toulouse VAACs, and seven supporting institutions and organisations. During the workshop, participants identified future improvements to the way the VOs and VAACs communicate and share information. Recommendations include refining the guidance and local documentation on the correct use of the Volcano Observatory Notice for Aviation (VONA), improving the two-way feedback between the VAAC and VOs, regular sharing of volcano status updates by the VO, and inclusion of all VOs in regular VAAC and aviation exercises. These are applicable to VOs and VAACs elsewhere in the world.

Applications of paleomagnetism and rock magnetism in understanding volcanic processes and timescales: perspectives to Korean volcanological research

Applications of paleomagnetism and rock magnetism in understanding volcanic processes and timescales: perspectives to Korean volcanological research

The >250-kyr Lake Chala record: A tephrostratotype correlating archaeological, palaeoenvironmental and volcanic sequences across eastern Africa

Regional tephrostratigraphic frameworks connect palaeoclimate, archaeological and volcanological records preserved in soils or lake sediments via shared volcanic ash (tephra) layers. In eastern Africa, tracing of tephra isochrons between geoarchaeological sequences is an established chronostratigraphic approach. However, to date, few long tephra records exist from sites with continuous depositional sequences, such as lake sediments, which offer the potential to connect local and discontinuous sequences at the regional scale. Long lake sediment sequences may also capture more complete eruptive histories of understudied volcanic centres. Here, we present and date the tephrostratigraphic record of a >250,000-year (>250-kyr) continuous sediment sequence extracted from Lake Chala, a crater lake on the Kenya-Tanzania border near Mt Kilimanjaro. Single-grain glass major and minor element analyses of visible and six cryptotephra layers reveal compositions ranging from mafic foidites and basanites to more evolved tephri-phonolites, phonolites, trachytes and a single rhyolite. Of these, nine are correlated to scoria cone eruptions of neighbouring Mt Kilimanjaro or the Chyulu volcanic field ∼60 km to the north; seven are correlated to phonolitic eruptions of Mt Meru, ∼100 km to the west; and four to voluminous trachytic eruptions of Central Kenyan Rift (CKR) volcanoes located ∼350 km to the north. The only rhyolitic tephra layer, a cryptotephra, correlates to the 73.7-ka BP (before present, taken as 1950 CE) Younger Toba Tuff (YTT) from Sumatra. Two of the CKR tephra layers provide direct ties with terrestrial sequences relevant to Middle Stone Age archaeology of the eastern Lake Victoria basin in Kenya. Absolute age estimates obtained by direct 40Ar/39Ar dating of 10 tephra layers are combined with six 210Pb and 162 14C dates covering the last 25-kyr and the well-constrained known age of the YTT to build a first absolute chronology for the full Lake Chala sediment sequence. The uninterrupted >250-kyr Lake Chala sedimentary archive represents a unique tephrostratotype sequence for eastern Africa, optimising the chronological value of tephra correlations in regional palaeoenvironmental, archaeological and volcanological research. Further study of cryptotephra in the Lake Chala sequence and additional geochemical characterisation and dating of ancient volcanic eruptions from nearby and further afield may eventually produce a regionally connected and detailed tephrostratigraphic framework for eastern equatorial Africa.

The Applicability and Productiveness of a Systematic Literature Review Methodology in Volcanology Research: Case of the Magma Pathway at the Mount Cameroon Volcano

The Applicability and Productiveness of a Systematic Literature Review Methodology in Volcanology Research: Case of the Magma Pathway at the Mount Cameroon Volcano

Socio-ecological impact of monogenetic volcanism in the La Garrotxa Volcanic Field (NE Iberia)

Volcanism can cause major impacts, including climate change and mass extinctions. However, the impact of monogenetic volcanism is often considered as limited in volcanological research. This work provides for the first time an interdisciplinary approach to the socio-ecological impact of monogenetic volcanism in a key region, the La Garrotxa Volcanic Field (GVF, Girona, NE Iberia), where intense monogenetic volcanic activity occurred in the past. The analyses of a sedimentary sequence from the GVF enabled identifying previously unknown volcanic eruptions in the time interval 14–8.4 ka cal BP, constrain their volcanic stratigraphy and age, and unfold the effects of environmental change on geomorphology, vegetation, aquatic organisms and humans. Moreover, we reconstruct the major palaeoenvironmental changes caused by the eruptions in terms of fire episodes and subsequent disturbance on vegetation, hydrology and limnological conditions. When put in context with the archaeological record, it appears that the last hunter–gatherer communities were resilient at an extra-local scale, facing episodes of vulnerability due to volcanic activity, suggesting that their flexible nomadic patterns and foraging economies were an efficient source of risk management against the volcanic eruptions and their ecological impacts.

The Contributions of Marine Sediment Cores to Volcanic Hazard Assessments: Present Examples and Future Perspectives

The rigorous assessment of volcanic hazards relies on setting contemporary monitoring observations within an accurate, longer-term geological context. Revealing that geological context requires the detailed fieldwork, mapping and laboratory analysis of the erupted materials. However, many of the world’s most dangerous volcanic systems are located on or near coasts (e.g., the Phlegraean Fields and Vesuvius in Italy), islands (e.g., the volcanic archipelagos of the Pacific, south-east Asia, and Eastern Caribbean), or underwater (e.g., the recently erupting Hunga Tonga–Hunga Ha’apai volcano), meaning that much of their erupted material is deposited on the sea bed. The only way to sample this material directly is with seafloor sediment cores. This perspectives paper outlines how marine sediment cores are a vital yet underused resource for assessing volcanic hazards by: (1) outlining the spatio-temporal scope of the marine volcanic record and its main deposit types, (2) providing existing examples where marine sediments have contributed to volcanic hazard assessments; (3) highlighting the Sunda Arc, Indonesia as an example location where marine sediment cores are yet to contribute to hazard assessments, and (4) proposing that marine sediment cores can contribute to our understanding of very large eruptions that have a global impact. Overall, this perspectives paper aims to promote the utility of marine sediment cores in future volcanic hazard assessments, while also providing some basic information to assist researchers who are considering integrating marine sediment cores into their volcanological research.

How inclusive is volcanology? Insights from global bibliometric analyses

In this study, we use bibliometric methods to assess the way in which local researchers are included in volcanological publications by comparing the affiliation of authors with the country in which researched volcanoes are located. Globally, 40 % of articles about a specific volcano do not include an author whose affiliation is based in the country where the volcano is located (a locally domiciled author), while 56 % are led by authors not based in the country of the volcano. Over the past three decades, first-authorship rates among local researchers have not increased. However, local researchers have becomemore frequently included as co-authors in research led by researchers domiciled elsewhere. We provide examples of how this bibliometric analysis can be used to evaluate several specific inclusion-related topics. The results of these analyses suggest that there is room for improvement in inclusivity in volcanological research and cause for reflection on how we collaborate with international partners.

Volcanism in Latin America: Advances in the region from the First ALVO Congress

The Latin American Association of Volcanology (ALVO) arose in 2010 as a regional network, promoting regional cooperation, the exchange of experiences and the strengthening of local capacities in the field of volcanology. In 2020, ALVO organized its first scientific congress under the slogan ‘Volcanology in and for Latin America’ (1er Congreso ALVO: Volcanología en y para Latinoamérica). The Special Issue, Volcanism in Latin America, hosts several works presented at this Congress. The articles that constitute this Special Issue cover a broad spectrum of topics studied by many research groups and institutions working on volcanology in the region. Such topics include disciplines like physical volcanology, geochemistry, seismology, remote sensing, volcano observatories, instrumentation, and volcanic hazards and risks, among others. These papers represent good examples of the state-of-the-art of volcanology research in Latin America.

Workflows for Construction of Spatio-Temporal Probabilistic Maps for Volcanic Hazard Assessment

Probabilistic hazard assessments for studying overland pyroclastic flows or atmospheric ash clouds under short timelines of an evolving crisis, require using the best science available unhampered by complicated and slow manual workflows. Although deterministic mathematical models are available, in most cases, parameters and initial conditions for the equations are usually only known within a prescribed range of uncertainty. For the construction of probabilistic hazard assessments, accurate outputs and propagation of the inherent input uncertainty to quantities of interest are needed to estimate necessary probabilities based on numerous runs of the underlying deterministic model. Characterizing the uncertainty in system states due to parametric and input uncertainty, simultaneously, requires using ensemble based methods to explore the full parameter and input spaces. Complex tasks, such as running thousands of instances of a deterministic model with parameter and input uncertainty require a High Performance Computing infrastructure and skilled personnel that may not be readily available to the policy makers responsible for making informed risk mitigation decisions. For efficiency, programming tasks required for executing ensemble simulations need to run in parallel, leading to twin computational challenges of managing large amounts of data and performing CPU intensive processing. The resulting flow of work requires complex sequences of tasks, interactions, and exchanges of data, hence the automatic management of these workflows are essential. Here we discuss a computer infrastructure, methodology and tools which enable scientists and other members of the volcanology research community to develop workflows for construction of probabilistic hazard maps using remotely accessed computing through a web portal.

The centenary of IAVCEI 1919-2019 and beyond: origins and evolution of the International Association of Volcanology and Chemistry of the Earth's Interior.

IAVCEI originated in 1919 as one of the six inaugural “sections” of the International Union of Geodesy and Geophysics (IUGG). IUGG was formed by the International Research Council, which has now evolved to become the International Science Council (ISC). In 1933 the Section for Volcanology was renamed the International Association of Volcanology (IAV), and in 1967, it became the International Association of Volcanology and Geochemistry of the Earth’s Interior (IAVCEI). IAVCEI has been managed by 22 Presidents, 10 Secretaries-General, and their executive committees/bureaus. IAVCEI has always had a focus on facilitating the communication of volcanological research through organising a variety of international conferences, including IAVCEI General Assemblies, Scientific Assemblies, occasional Volcanological Congresses, and Cities on Volcanoes conferences. In addition, IAVCEI established research working groups initially which then became the association’s research commissions. The research commissions have also organised their own research workshops. Recently IAVCEI has also developed new groupings of researchers through their Network program, including the Early Career Researcher Network, which focus mostly on facilitating communication. Bulletin of Volcanology has been the official IAVCEI journal since 1924 and has undergone several facelifts in its cover and format. It has been very well served by its 11 volunteer editors, editorial board, and reviewers in almost 100 years of publication. In addition, IAVCEI was instrumental in instigating an inventory of known volcanoes through its Catalogue of the Volcanoes of the World series, a role now undertaken by the Smithsonian Institution. To acknowledge outstanding achievements in volcanological research, IAVCEI has established 6 awards since 1974. Developing a better understanding of how volcanoes erupt and the impacts of eruptions on society has been an integral responsibility of IAVCEI as the learned international association in volcanology. In the 1990s, IAVCEI initiated the Decade Volcanoes program to encourage research on 16 volcanoes that were deemed to pose significant risks to the communities around them. Some have erupted since then, but eruptions from other volcanoes have also provided significant insights into eruption processes and phenomena. Although IAVCEI’s future looks healthy, there are ways of being more proactive in improving services to members, including improving diversity and inclusiveness, greater gender balance for all positions on the IAVCEI Executive Committee, widening the representation of nationalities that serve on the Executive Committee, increasing membership numbers to generate greater income to support scientists in need of support to participate in IAVCEI activities, and significantly lowering the fee for open access publication of research papers in IAVCEI’s masthead journal, Bulletin of Volcanology.Supplementary InformationThe online version contains supplementary material available at 10.1007/s00445-021-01509-5.

Volcanic Lakes in Africa: The VOLADA_Africa 2.0 Database, and Implications for Volcanic Hazard

Volcanic lakes pose specific hazards inherent to the presence of water: phreatic and phreatomagmatic eruptions, lahars, limnic gas bursts and dispersion of brines in the hydrological network. Here we introduce the updated, interactive and open-access database for African volcanic lakes, country by country. The previous database VOLADA (VOlcanic LAke DAta Base, Rouwet et al., Journal of Volcanology and Geothermal Research, 2014, 272, 78–97) reported 96 volcanic lakes for Africa. This number is now revised and established at 220, converting VOLADA_Africa 2.0 in the most comprehensive resource for African volcanic lakes: 81 in Uganda, 37 in Kenya, 33 in Cameroon, 28 in Madagascar, 19 in Ethiopia, 6 in Tanzania, 2 in Rwanda, 2 in Sudan, 2 in D.R. Congo, 1 in Libya, and 9 on the minor islands around Africa. We present the current state-of-the-art of arguably all the African volcanic lakes that the global experts and regional research teams are aware of, and provide hints for future research directions, with a special focus on the volcanic hazard assessment. All lakes in the updated database are classified for their genetic origin and their physical and chemical characteristics, and level of study. The predominant rift-related volcanism in Africa favors basaltic eruptive products, leading to volcanoes with highly permeable edifices, and hence less-developed hydrothermal systems. Basal aquifers accumulate under large volcanoes and in rift depressions providing a potential scenario for phreatomagmatic volcanism. This hypothesis, based on a morphometric analysis and volcanological research from literature, conveys the predominance of maar lakes in large monogenetic fields in Africa (e.g. Uganda, Cameroon, Ethiopia), and the absence of peak-activity crater lakes, generally found at polygenetic arc-volcanoes. Considering the large number of maar lakes in Africa (172), within similar geotectonic settings and meteoric conditions as in Cameroon, it is somewhat surprising that “only” from Lake Monoun and Lake Nyos fatal CO2 bursts have been recorded. Explaining why other maars did not experience limnic gas bursts is a question that can only be answered by enhancing insights into physical limnology and fluid geochemistry of the so far poorly studied lakes. From a hazard perspective, there is an urgent need to tackle this task as a community.

Synoptic analysis of a decade of daily measurements of SO<sub>2</sub> emission in the troposphere from volcanoes of the global ground-based Network for Observation of Volcanic and Atmospheric Change

Abstract. Volcanic plumes are common and far-reaching manifestations of volcanic activity during and between eruptions. Observations of the rate of emission and composition of volcanic plumes are essential to recognize and, in some cases, predict the state of volcanic activity. Measurements of the size and location of the plumes are important to assess the impact of the emission from sporadic or localized events to persistent or widespread processes of climatic and environmental importance. These observations provide information on volatile budgets on Earth, chemical evolution of magmas, and atmospheric circulation and dynamics. Space-based observations during the last decades have given us a global view of Earth's volcanic emission, particularly of sulfur dioxide (SO2). Although none of the satellite missions were intended to be used for measurement of volcanic gas emission, specially adapted algorithms have produced time-averaged global emission budgets. These have confirmed that tropospheric plumes, produced from persistent degassing of weak sources, dominate the total emission of volcanic SO2. Although space-based observations have provided this global insight into some aspects of Earth's volcanism, it still has important limitations. The magnitude and short-term variability of lower-atmosphere emissions, historically less accessible from space, remain largely uncertain. Operational monitoring of volcanic plumes, at scales relevant for adequate surveillance, has been facilitated through the use of ground-based scanning differential optical absorption spectrometer (ScanDOAS) instruments since the beginning of this century, largely due to the coordinated effort of the Network for Observation of Volcanic and Atmospheric Change (NOVAC). In this study, we present a compilation of results of homogenized post-analysis of measurements of SO2 flux and plume parameters obtained during the period March 2005 to January 2017 of 32 volcanoes in NOVAC. This inventory opens a window into the short-term emission patterns of a diverse set of volcanoes in terms of magma composition, geographical location, magnitude of emission, and style of eruptive activity. We find that passive volcanic degassing is by no means a stationary process in time and that large sub-daily variability is observed in the flux of volcanic gases, which has implications for emission budgets produced using short-term, sporadic observations. The use of a standard evaluation method allows for intercomparison between different volcanoes and between ground- and space-based measurements of the same volcanoes. The emission of several weakly degassing volcanoes, undetected by satellites, is presented for the first time. We also compare our results with those reported in the literature, providing ranges of variability in emission not accessible in the past. The open-access data repository introduced in this article will enable further exploitation of this unique dataset, with a focus on volcanological research, risk assessment, satellite-sensor validation, and improved quantification of the prevalent tropospheric component of global volcanic emission. Datasets for each volcano are made available at https://novac.chalmers.se (last access: 1 October 2020) under the CC-BY 4 license or through the DOI (digital object identifier) links provided in Table 1.

Outcomes from a visitors study at the “INGV Open Day Event”

Research Institutions are tackling the ever so increasing challenge to share the outcomes of scientific research and technological innovations with a forthright method in order to increase involvement of the community. To achieve that aim, the main recipients of the information must be the focus point on which outreach and educational activities concentrate. Standard analysis of visitor’s experiences within informal learning activities can provide useful information on the activity impacts. In fact, evaluating the performance allows to improve the effects, achievements and benefits in the audiences. This research was carried out by analysing quantitative and qualitative studies performed in the occasion of a temporary outreach event, in which visitors were the focal point. Different types of audiences were examined during an Open Day at the Istituto Nazionale di Geofisica e Vulcanologia (INGV)—Italian Institute of Geophysical and Volcanological Research—based in Rome, leading to the results we present in this work. The event was remarkable as it brought together a broad selection of scientific laboratories, exhibition spaces and meetings with researchers, all custom tailored towards the specific audiences. At the end of the event, questionnaires were handed over to the visitors, both young and adults, and to any stakeholder that were present. The answers and the open feedbacks from the visitors have disclosed valuable information on INGV’s audience, and allowed the events organization and contents to be refined and improved. This procedure can most certainly be turned into a methodical system to obtain a general picture of the cognitive and emotional effects on visitors participating in scientific itineraries. The quantitative method used in this research involved analysing the answers in the questionnaires with a statistical approach and was blended with the qualitative method that took into account the visitor’s personal feedback and input. The aftermath of the study allows to pinpoint the main event issues and to take actions aimed to enrich visitor’s satisfaction and experience. In fact, advertising of the events ahead of time, arranging a well designed and implemented online information and booking system in order to better accommodate for the number of visitors, realizing dedicated apps for the each tours, creating a shorter questionnaire for children, and creating standards for questionnaires that would be used in the future.

The Late Bronze Age Eruption of Santorini Volcano and Its Impact on the Ancient Mediterranean World

The Late Bronze Age eruption of Santorini occurred 110 km north of Minoan Crete (Greece). Having discharged between 48 and 86 km3 of magma and rock debris, the eruption ranks as one of the largest of the last 10,000 years. On Santorini, it buried the affluent trading port of Akrotiri. Modern volcanological research has reconstructed the eruption and its regional impacts in detail, while fifty years of archaeological excavations have unraveled the events experienced by the inhabitants of Akrotiri during the months that led up to the eruption. Findings do not favour a direct relationship between the eruption and the decline of the Minoan civilization, although tsunamis and atmospheric effects may have weakened Cretan society through impacts on shipping, trade and agriculture.

Long-Term Monitoring with Fiber Optics Distributed Temperature Sensing at Campi Flegrei: The Campi Flegrei Deep Drilling Project.

Monitoring volcanic phenomena is a key question, for both volcanological research and for civil protection purposes. This is particularly true in densely populated volcanic areas, like the Campi Flegrei caldera, which includes part of the large city of Naples (Italy). Borehole monitoring of volcanoes is the most promising way to improve classical methods of surface monitoring, although not commonly applied yet. Fiber optics technology is the most practical and suitable way to operate in such high temperature and aggressive environmental conditions. In this paper, we describe a fiber optics Distributed Temperature Sensing (DTS) sensor, which has been designed to continuously measure temperature all along a 500 m. deep well drilled in the west side of Naples (Bagnoli area), lying in the Campi Flegrei volcanic area. It has then been installed as part of the international ‘Campi Flegrei Deep Drilling Project’, and is continuously operating, giving insight on the time variation of temperature along the whole borehole depth. Such continuous monitoring of temperature can in turn indicate volcanic processes linked to magma dynamics and/or to changes in the hydrothermal system. The developed monitoring system, working at bottom temperatures higher than 100 °C, demonstrates the feasibility and effectiveness of using DTS for borehole volcanic monitoring.

A review of laboratory and numerical modelling in volcanology

Abstract. Modelling has been used in the study of volcanic systems for more than 100 years, building upon the approach first applied by Sir James Hall in 1815. Informed by observations of volcanological phenomena in nature, including eye-witness accounts of eruptions, geophysical or geodetic monitoring of active volcanoes, and geological analysis of ancient deposits, laboratory and numerical models have been used to describe and quantify volcanic and magmatic processes that span orders of magnitudes of time and space. We review the use of laboratory and numerical modelling in volcanological research, focussing on sub-surface and eruptive processes including the accretion and evolution of magma chambers, the propagation of sheet intrusions, the development of volcanic flows (lava flows, pyroclastic density currents, and lahars), volcanic plume formation, and ash dispersal. When first introduced into volcanology, laboratory experiments and numerical simulations marked a transition in approach from broadly qualitative to increasingly quantitative research. These methods are now widely used in volcanology to describe the physical and chemical behaviours that govern volcanic and magmatic systems. Creating simplified models of highly dynamical systems enables volcanologists to simulate and potentially predict the nature and impact of future eruptions. These tools have provided significant insights into many aspects of the volcanic plumbing system and eruptive processes. The largest scientific advances in volcanology have come from a multidisciplinary approach, applying developments in diverse fields such as engineering and computer science to study magmatic and volcanic phenomena. A global effort in the integration of laboratory and numerical volcano modelling is now required to tackle key problems in volcanology and points towards the importance of benchmarking exercises and the need for protocols to be developed so that models are routinely tested against real world data.

Ground-Based Remote Sensing and Imaging of Volcanic Gases and Quantitative Determination of Multi-Species Emission Fluxes

The physical and chemical structure and the spatial evolution of volcanic plumes are of great interest since they influence the Earth’s atmospheric composition and the climate. Equally important is the monitoring of the abundance and emission patterns of volcanic gases, which gives insight into processes in the Earth’s interior that are difficult to access otherwise. Here, we review spectroscopic approaches (from ultra-violet to thermal infra-red) to determine multi-species emissions and to quantify gas fluxes. Particular attention is given to the emerging field of plume imaging and quantitative image interpretation. Here UV SO2 cameras paved the way but several other promising techniques are under study and development. We also give a brief summary of a series of initial applications of fast imaging techniques for volcanological research.

From magma ascent to ash generation: investigating volcanic conduit processes by integrating experiments, numerical modeling, and observations

Processes occurring in volcanic conduits, the pathways through which magma travels from its storage region to the surface, have a fundamental control on the nature of eruptions and associated phenomena. It has been well established that magma flows, crystallizes, degasses, and fragments in conduits, that fluids migrate in and out of conduits, and that seismic and acoustic waves are generated and travel within conduits. A better understanding of volcanic conduits and related processes is of paramount importance for improving eruption forecasting, volcanic hazard assessment and risk mitigation. However, despite escalating advances in the characterization of individual conduit processes, our understanding of their mutual interactions and the consequent control on volcanic activity is still limited. With the purpose of addressing this topic, a multidisciplinary workshop led by a group of international scientists was hosted from 25 to 27 October 2014 by the Pisa branch of the Istituto Nazionale di Geofisica e Vulcanologia under the sponsorship of the MeMoVolc Research Networking Programme of the European Science Foundation. The workshop brought together the experimental, theoretical, and observational communities devoted to volcanological research. After 3 days of oral and poster presentations, breakout sessions, and plenary discussions, the participants identified three main outstanding issues common to experimental, analytical, numerical, and observational volcanology: unsteadiness (or transience), disequilibrium, and uncertainty. A key outcome of the workshop was to identify the specific knowledge areas in which exchange of information among the sub-disciplines would lead to efficient progress in addressing these three main outstanding issues. It was clear that multidisciplinary collaboration of this sort is essential for progressing the state of the art in understanding of conduit magma dynamics and eruption behavior. This holistic approach has the ultimate aim to deliver fundamental improvements in understanding the underlying processes generating and controlling volcanic activity.

The history of volcanology in Costa Rica: from the Amerindian legends to the beginning of the twenty-first century

Abstract We divide the narrative history of legends on volcanoes, descriptions of volcanic landscape, eruptions and products, and the gradual development of volcanology in Costa Rica as a formal science, into several periods or stages. Each stage is discussed in detail in the text: (a) pre-Columbian period (11 500 BC–AD 1502); (b) colonization period (1502–1718); (c) first period (1719–1887); (d) second period (1888–1925); (e) third period (1926–62), and (f) fourth period (1963–present). The social and economic contribution of volcanology research is also discussed.

An alternate perspective on the opening and closing of the intracratonic Purana basins in peninsular India

absolutely unaffected and found as ‘fresh limestones’ as is directly evident from their micritic nature with clayey intercalations under microscope and the laminations/bandings visible even on a handspecimen scale besides their geochemical attributes (lack of influence of kimberlite bulk-geochemistry). Such limestone xenoliths must have been incorporated into the kimberlite magma at a much shallower depths (close to the surface), thereby necessitating their survival and non-reactiveness, and certainly not ‘exhumed’ being entrapped in the kimberlite as expressed by Prof Kale. We also wish to point out that the presence of ‘fresh limestones’ in a kimberlite is not a ‘remarkable’, aspect but in fact has been well-documented and quite familiar to those involved in research on kimberlites. For example, ‘fresh limestone xenoliths (some of them with profuse conodont fossils) have been recovered from the kimberlites occuring in the Slave (Cookenboo et al. 1998; Geology, v.26, n.5, pp. 391-394) and Saskatchewan (Lefebvre and Kurszlaukis, 2008; Journal of Volcanology and Geothermal Research v.174, pp. 171-185) cratons of Canada and constitute the only solid evidence that sea water inundated, in the geological past, in the now exposed cratons. Likewise, fossiliferous limestone xenoliths derived from the kimberlites of the Baffin Island, Nunavut, Canada (Zhand and Pell, 2014; Canadian Journal of Earth Sciences v.51, pp. 142-155) confirm the Paleozoic cover in this domain. We do agree with Prof. Kale that despite more than a century of study many apects of the Purana basins still remain open to debate. We also deeply appreciate the remarkable efforts made in recent years by Prof Abhijit Basu and his co-workers for reviving interest in these fascinating basins.