Global Volcanism Program Research Articles

Global volcanic rock classification of Holocene volcanoes

This data descriptor assigns the major and minor rock names from worldwide Holocene volcanoes of the Global Volcanism Program (GVP) using the Total Alkali-Silica diagram (TAS) for the chemical classification of volcanic rocks using the Geochemistry of Rocks of the Oceans and Continents (GEOROC) database. The precompiled files of the GEOROC database provide the chemical composition of volcanic rock samples, from which we computed major and minor rocks for global Holocene volcanoes reported in GVP. The combined dataset associates each volcano with the relative abundance of each volcanic sample type (whole rock, glass, melt inclusion) and provides the five major (more than 10% abundance) and minor rock names. In total, over 138,000 GEOROC volcanic rock samples were considered, for ~1000 Holocene volcanoes. The resulting major rock compositions are in general consistent with those given in GVP. The dataset provides a global panorama of rock composition for Holocene volcanoes.

An Investigation of Volcanic Ground Deformation Using InSAR Observations at Tendürek Volcano (Turkey)

Although approximately one-tenth of the world’s population lives near volcanoes, most of the 1500 active volcanoes are not monitored by ground-based instruments because of the cost and difficulty of access. Since the development of interferometric synthetic aperture radar (InSAR) in the 1990s, recent advances have allowed the near-real-time detection of surface deformations, one of the earliest markers of volcanic activity. According to the Global Volcanism Program, Turkey’s most recent eruption (involving gas and ash) occurred in the Tendürek volcano in 1885. An explosion in the Tendürek volcano, which continues to actively output gas and steam, would be a critical issue for the life and property of the people living nearby. In this context, we processed the Sentinel-1 data collected by the European Space Agency using the Stanford Method for Persistent Scatterers, and the surface deformations of the Tendürek volcano were investigated. In addition, we applied two different atmospheric correction approaches (linear phase-based tropospheric correction and the Generic Atmospheric Correction Online Service for InSAR) to reduce atmospheric effects and found that the linear phase-based tropospheric correction model produced lower standard deviation values. Subsequently, the mean deformation velocity maps, displacement time series, and deformation components in the line-of-sight direction were calculated. The results showed that the most severe subsidence was −11 mm/yr on the upper slopes of the Tendürek volcano. Although the lower slopes of the subsidence region have a lower settlement rate, the subsidence has a peak-caldera-centered location.

Integrating global geochemical volcano rock composition with eruption history datasets

The major element composition of volcanic rocks carries important information about the source and differentiation processes affecting the magma, the physical properties that allow it to erupt, and its eruptive style. Although global rock geochemical databases exist, these are not linked to volcanic eruption history which hampers our global understanding of the relationship between magma composition and eruption dynamics. Here, we integrate two global databases, the Geochemistry of Rocks of the Oceans and Continents (GEOROC) and the Holocene volcanoes of the world of the Global Volcanism Program (VOTW-GVP). The integration is based on matching the location name, geographic position and eruption time, which is automated by a tool called DashVolcano. The tool is open-source, accessible at https://github.com/feog/DashVolcano, and gives access to the integrated datasets via an interactive dashboard. DashVolcano is based on more than 138,000 volcanic rock samples and provides the basis for the identification of global relationships between eruption styles, volcano types, and rock composition for more than 700 volcanoes and their eruptions for the last 10,000 years. The combined record of the eruptive history and its corresponding geochemical rock composition that DashVolcano provides can be used for characterizing global geochemical differences between volcanoes, and should also prove useful for improved long-term hazard and risk evaluations.

Spatial and Temporal Quantification of Subaerial Volcanism From 1980 to 2019: Solid Products, Masses, and Average Eruptive Rates

AbstractVolcanism is one of the main mechanisms transferring mass and energy between the interior of the Earth and the Earth's surface. However, the global mass flux of lava, volcanic ash and explosive pyroclastic deposits is not well constrained. Here we review published estimates of the mass of the erupted products from 1980 to 2019 by a global compilation. We identified 1,064 magmatic eruptions that occurred between 1980 and 2019 from the Smithsonian Global Volcanism Program database. For each eruption, we reported both the total erupted mass and its partitioning into the different volcanic products. Using this data set, we quantified the temporal and spatial evolution of subaerial volcanism and its products from 1980 to 2019 at a global and regional scale. The mass of magma erupted in each analyzed decade ranged from 1.1–4.9 × 1013 kg. Lava is the main subaerial erupted product representing ∼57% of the total erupted mass of magma. The products related to the biggest eruptions (Magnitude ≥6), with long recurrence times, can temporarily make explosive products more abundant than lava (e.g., decade 1990–1999). Twenty‐three volcanoes produced ∼72% of the total mass, while two different sets of 15 volcanoes erupted >70% of the total mass of either effusive or explosive products. At a global scale, the 10 and 40‐year average eruptive rates calculated from 1980 to 2019 have the same magnitude as the long‐term average eruptive rates (from thousand to millions of years), because in both cases rates are scaled for times comparable to the recurrence time of the biggest eruptions occurred.

Volcanic Activity on Venus: How Long Must We Look to Find a Smoking Gun?

AbstractWhile volcanic landforms attest to the numerous and varied volcanic processes on Venus, estimates of the frequency of volcanic eruptions are lacking. Constraints from volcanic resurfacing volumes can be equally satisfied by infrequent large eruptions or numerous smaller events. Recently, Byrne and Krishnamoorthy (2022), https://doi.org/10.1029/2021JE007040, used the 40‐year period from 1980 to 2020 from the Smithsonian Global Volcanism Program (GVP) database (Global Volcanism Program, 2013) to extrapolate the frequency of volcanic events on Earth to Venus. They evaluated the tectonic settings from the GVP database and provided estimates that consider the differences in those settings between Earth and Venus. Byrne and Krishnamoorthy extrapolated the rate of volcanism between Earth and Venus using the mass/volume ratios, freeing their results from the uncertain tectonic evolution of Venus. The assumption that Venus is in a stagnant‐lid tectonic regime with a straight‐forward geodynamic evolution has been challenged by Weller and Kiefer (2020), https://doi.org/10.1029/2019je005960, who showed that a planetary surface may reflect different styles of convection with highly active and sluggish and inactive regions occurring at the same time. The straight‐forward scaling allowed Byrne and Krishnamoorthy to estimate that as many as 120 eruptions might take place on Venus every year, a frequency that should be detectable by upcoming Venus missions.

How big will the next eruption be?

Anticipating the size of the next volcanic eruption in long-term forecasts is a major problem in both basic and applied volcanology. In this study, we investigate the extent to which eruption size is predictable based on historical and other attribute data. Data from the Smithsonian Global Volcanism Program (GVP) Catalog is used to determine the predictability of volcanic eruption size as quantified through the reported VEI (Volcano Explosivity Index). The numerical and categorical attributes from the global volcanic catalog were classified with trained random forest and simple prediction models to make a forecast of VEI that can be tested against the most recent eruption of each volcano. We compare these results to two different baseline predictability levels by: (a) selecting randomly from the global distribution of VEIs for the most recent eruptions to calculate a cohort baseline and (b) selecting the most frequent VEI for a given population to calculate a zero-rule baseline. We found that: (1) nearly any method that incorporates prior information on a specific volcano improves the prediction accuracy of the succeeding eruption VEI by at least 10 percentage points relative to the cohort baseline case, (2) incorporating attributes beyond previous VEIs can provide better accuracy and achieve up to 30 percentage point accuracy gains, (3) total accuracy of the VEI forecasting by these methods can be up to nearly 80% and (4) the zero-rule is an effective prediction method that is modestly outperformed (~ 5 percentage point gain) by random forest methods with multiple attributes on most datasets. We find no notable preference in accuracy based on volcano type. The results quantify the importance of volcano-specific information in long-term forecasting and may help practitioners assess their expected performance when anticipating future eruption size.

Detailed Mapping of Lava and Ash Deposits at Indonesian Volcanoes by Means of VHR PlanetScope Change Detection

Mapping of lava flows in unvegetated areas of active volcanoes using optical satellite data is challenging due to spectral similarities of volcanic deposits and the surrounding background. Using very high-resolution PlanetScope data, this study introduces a novel object-oriented classification approach for mapping lava flows in both vegetated and unvegetated areas during several eruptive phases of three Indonesian volcanoes (Karangetang 2018/2019, Agung 2017, Krakatau 2018/2019). For this, change detection analysis based on PlanetScope imagery for mapping loss of vegetation due to volcanic activity (e.g., lava flows) is combined with the analysis of changes in texture and brightness, with hydrological runoff modelling and with analysis of thermal anomalies derived from Sentinel-2 or Landsat-8. Qualitative comparison of the mapped lava flows showed good agreement with multispectral false color time series (Sentinel-2 and Landsat-8). Reports of the Global Volcanism Program support the findings, indicating the developed lava mapping approach produces valuable results for monitoring volcanic hazards. Despite the lack of bands in infrared wavelengths, PlanetScope proves beneficial for the assessment of risk and near-real-time monitoring of active volcanoes due to its high spatial (3 m) and temporal resolution (mapping of all subaerial volcanoes on a daily basis).

Long-Term Probabilistic Volcanic Hazard Assessment Using Open and Non-open Data: Observations and Current Issues

Probabilistic volcanic hazard assessment (PVHA) has become the paradigm to quantify volcanic hazard over the last decades. Substantial aleatory and epistemic uncertainties in PVHA arise from complexity of physico-chemical processes, impossibility of their direct observation and, importantly, a severe scarcity of observables from past eruptions. One factor responsible for data scarcity is the infrequency of moderate/large eruptions; other factors include lack of discoverability and accessibility to volcanological data. Open-access databases can help alleviate data scarcity and have significantly contributed to long-term PVHA of eruption onset and size, while are less common for data required in other PVHA components (e.g. vent opening). Making datasets open is complicated by economical, technological, ethical and/or policy-related challenges. International synergies (e.g. Global Volcanism Program, WOVOdat, Global Volcano Model, EPOS) will be key to facilitate the creation and maintenance of open-access databases that support Next-Generation PVHA. Additionally, clarification of some misconceptions about PVHA can also help progress. Firstly, PVHA should be understood as an expansion of deterministic, scenario-based hazard assessments. Secondly, a successful PVHA should sometimes be evaluated by its ability to deliver useful and usable hazard-related messages that help mitigate volcanic risk. Thirdly, PVHA is not simply an end product but a driver for research: identifying the most relevant sources of epistemic uncertainty can guide future efforts to reduce the overall uncertainty. Broadening of the volcanological community expertise to statistics or engineering has already brought major breakthroughs in long-term PVHA. A vital next step is developing and maintaining more open-access datasets that support PVHA worldwide.

The analysis of spatial distributions, origins of caldera-forming eruptions with basaltic-andesitic magma compositions, and genesis of Miocene ignimbrites of the Eastern volcanic belt, Kamchatka

Based on the statistical data of the Global Volcanism Program of the Smithsonian Institution and published materials, we present a comparative analysis of caldera-forming eruptions on global scale. The geodynamic settings and genesis of the caldera-forming eruptions with basaltic-andesitic magma compositions are described. The origin of the majority of mafic ignimbrites was related with external water. Such ignimbrites were generated in a submarine environment or with a contact with water. The newly obtained data, paleogeodynamic reconstruction and geological mapping of Miocene mafic ignimbrites of the Eastern volcanic belt (EVB) of Kamchatka confirm their genesis in costal-marine environment. These new data show significance of paleoreconstructions in studies of paleo-volcanoes and relief-forming pyroclastic rocks.

Applying Vocabularies to a Large, Historic Geoscience Collection

Geoscience collections have data needs that are broadly consistent with, but differ in important ways from, biology collections. Non-paleontology geoscience collections have received particularly little attention because they do not fit easily into the biodiversity framework that encompasses most natural history collections. Here we describe efforts to apply controlled vocabularies to the rock, mineral, and meteorite collections of the Department of Mineral Sciences in the Smithsonian Institution's National Museum of Natural History. Controlled vocabularies encourage consistency in usage of terms, connect related terms and concepts, and simplify discovery and re-use of data. Developing and implementing vocabularies for geoscience collections is a key step in better integrating these collections into the broader natural history landscape. The Mineral Sciences collections contain approximately 450,000 specimens collected over 150 years. Specimen records therefore contain a large number of archaic terms and vary widely in the quality and amount of descriptive metadata available. We targeted four fields judged most likely to benefit from using a vocabulary: rock/mineral classification (using terms from the British Geological Survey Rock Classification Scheme, the International Mineralogicial Association's list of minerals, and other sources); rock microstructure (using terms from GeoScience Markup Language, or GeoSciML); stratigraphy (using MacroStrat); and collection locality (using terms from GeoNames and the Global Volcanism Program). This process highlighted many of the challenges of grafting vocabularies onto existing data of varying age and quality, including: A lack of comprehensive, widely used vocabularies for geosciences Ambiguities in usage between the specimen database and the controlled vocabulary Widespread use of archaic terms that must be defined or replaced Difficulty shoehorning vocabularies into databases not designed to accommodate them Tension between the needs of data management and collection management A lack of comprehensive, widely used vocabularies for geosciences Ambiguities in usage between the specimen database and the controlled vocabulary Widespread use of archaic terms that must be defined or replaced Difficulty shoehorning vocabularies into databases not designed to accommodate them Tension between the needs of data management and collection management Even with these difficulties, implementing vocabularies has made it easier to retrieve and interpret specimen data, especially for queries of rock/mineral classification and locality information, and is a useful step in encouraging wider use of data from the collections.

Intra-eruption forecasting

Forecasting eruption onsets has received much attention, in both the short and long term. However, an eruption is not easily reduced to an instant in time, and forecasting what happens after eruption onset has received little attention. Any useful definition of an eruption has to allow for activity over scales ranging from days to decades, and can do so only by allowing for multiple eruptive phases. These phases can be defined by having different styles (e.g. effusive and/or explosive) of activity and/or quiescent periods between them. A vital question then presents itself: given what we have seen so far of the eruption, what is likely to happen next? We have recoded a global database of multiple-phase eruptions provided by the Smithsonian Institution’s Global Volcanism Program and the USGS into eight major styles of activity. The resulting database contains c. 700 multi-phase eruptions, with each eruption having up to 50 non-quiescent phases. The resulting record of transitions between states is relatively dense, and a probability tree that models 850 possible phase sequences is infeasible. Thus, we use (semi-)Markov chain models in order to assess the probability of transitioning from one phase of activity to another, as a function of the recent eruption activity. Markov chains describe the path from state to state i.e. from one style of activity to another, under the assumption that only the present state determines the probability of the next state, but the definition of ‘state’ can be extended. The ‘order’ of a Markov chain is the number of previous consecutive phases that are considered to define the current state controlling the next transition, and thus higher order Markov chains can account for a greater degree of memory. A semi-Markov chain is one in which the duration in a given state is not necessarily memoryless. We show how a second-order semi-Markov chain can be used to calculate likelihoods for the next style of activity during an eruption, conditional on the type and elapsed duration of the current phase, and the type and duration of the one preceding it. We find that solely effusive behaviour is unlikely to precede violent explosions, and that Plinian eruptions only become more likely during a sequence once a major eruption occurs. A quantitative method for forecasting intra-eruptive activity supports long-term and short-term decision making. To further refine the model, we discuss possible future developments to differentiate between volcanoes, and to incorporate monitoring data in real time to update forecasts.

Thermal, Deformation, and Degassing Remote Sensing Time Series (CE 2000–2017) at the 47 most Active Volcanoes in Latin America: Implications for Volcanic Systems

AbstractVolcanoes are hazardous to local and global populations, but only a fraction are continuously monitored by ground‐based sensors. For example, in Latin America, more than 60% of Holocene volcanoes are unmonitored, meaning long‐term multiparameter data sets of volcanic activity are rare and sparse. We use satellite observations of degassing, thermal anomalies, and surface deformation spanning 17 years at 47 of the most active volcanoes in Latin America and compare these data sets to ground‐based observations archived by the Global Volcanism Program. This first comparison of multisatellite time series on a regional scale provides information regarding volcanic behavior during, noneruptive, pre‐eruptive, syneruptive, and posteruptive periods. For example, at Copahue volcano, deviations from background activity in all three types of satellite measurements were manifested months to years in advance of renewed eruptive activity in 2012. By quantifying the amount of degassing, thermal output, and deformation measured at each of these volcanoes, we test the classification of these volcanoes as open or closed volcanic systems. We find that ~28% of the volcanoes do not fall into either classification, and the rest show elements of both, demonstrating a dynamic range of behavior that can change over time. Finally, we recommend how volcano monitoring could be improved through better coordination of available satellite‐based capabilities and new instruments.

Analysis of air mass back trajectories with present and historical volcanic activity and anthropogenic compounds to infer pollution sources in the South Shetland Islands (Antarctica)

Abstract This work analyses atmospheric transport of natural and anthropogenic pollution to the South Shetland Islands (SSI), with particular reference to the period September 2015 – August 2017. Based on data from the Global Volcanism Program database and air mass back trajectories calculated using the HySPLIT model, it was found that it is possible that in the analysed period volcanic pollution was supplied via long-range transport from South America, and from the South Sandwich Islands. Air masses flowed in over the South Shetland Islands from the South America region relatively frequently – 226 times during the study period, which suggests the additional possibility of anthropogenic pollution being supplied by this means. In certain cases the trajectories also indicated the possibility of atmospheric transport from the New Zealand region, and even from the south-eastern coast of Australia. The analysis of the obtained results is compared against the background of research by other authors. This is done to indicate that research into the origin of chemical compounds in the Antarctic environment should take into account the possible influx of pollutants from remote areas during the sampling period, as well as the possible reemission of compounds accumulated in snow and ice.

Automated detection and cataloging of global explosive volcanism using the International Monitoring System infrasound network

AbstractWe experiment with a new method to search systematically through multiyear data from the International Monitoring System (IMS) infrasound network to identify explosive volcanic eruption signals originating anywhere on Earth. Detecting, quantifying, and cataloging the global occurrence of explosive volcanism helps toward several goals in Earth sciences and has direct applications in volcanic hazard mitigation. We combine infrasound signal association across multiple stations with source location using a brute‐force, grid‐search, cross‐bearings approach. The algorithm corrects for a background prior rate of coherent unwanted infrasound signals (clutter) in a global grid, without needing to screen array processing detection lists from individual stations prior to association. We develop the algorithm using case studies of explosive eruptions: 2008 Kasatochi, Alaska; 2009 Sarychev Peak, Kurile Islands; and 2010 Eyjafjallajökull, Iceland. We apply the method to global IMS infrasound data from 2005–2010 to construct a preliminary acoustic catalog that emphasizes sustained explosive volcanic activity (long‐duration signals or sequences of impulsive transients lasting hours to days). This work represents a step toward the goal of integrating IMS infrasound data products into global volcanic eruption early warning and notification systems. Additionally, a better understanding of volcanic signal detection and location with the IMS helps improve operational event detection, discrimination, and association capabilities.

Assessing the altitude and dispersion of volcanic plumes using MISR multi-angle imaging from space: Sixteen years of volcanic activity in the Kamchatka Peninsula, Russia

Volcanic eruptions represent a significant source of atmospheric aerosols and can display local, regional and global effects, impacting earth systems and human populations. In order to assess the relative impacts of these events, accurate plume injection altitude measurements are needed. In this work, volcanic plumes generated from seven Kamchatka Peninsula volcanoes (Shiveluch, Kliuchevskoi, Bezymianny, Tolbachik, Kizimen, Karymsky and Zhupanovsky), were identified using over 16years of Multi-angle Imaging SpectroRadiometer (MISR) measurements. Eighty-eight volcanic plumes were observed by MISR, capturing 3–25% of reported events at individual volcanoes. Retrievals were most successful where eruptive events persisted over a period of weeks to months. Compared with existing ground and airborne observations, and alternative satellite-based reports compiled by the Global Volcanism Program (GVP), MISR plume height retrievals show general consistency; the comparison reports appear to be skewed towards the region of highest concentration observed in MISR-constrained plume vertical extent. The report observations display less discrepancy with MISR toward the end of the analysis period (2013–2016), with improvements in the suborbital data likely the result of the deployment of new instrumentation. Conversely, the general consistency of MISR plume heights with conventionally reported observations supports the use of MISR in the ongoing assessment of volcanic activity globally, especially where ground-based observations are unavailable. Differences between the northern (Shiveluch, Kliuchevskoi, Bezymianny and Tolbachik) and southern (Kizimen, Karymsky and Zhupanovsky) volcanoes broadly corresponding to the Central Kamchatka Depression (CKD) and Eastern Volcanic Front (EVF) geological sub-regions of Kamchatka, respectively, are distinguished by varying magma composition. For example, by comparison with reanalysis-model simulations of local meteorological conditions, CKD plumes were generally less constrained by mid-tropospheric (<6km) layers of vertical stability above the boundary layer, suggesting that these eruptions were more energetic than those in the EVF region.

30-year lidar observations of the stratospheric aerosol layer state over Tomsk (Western Siberia, Russia)

Abstract. There are only four lidar stations in the world which have almost continuously performed observations of the stratospheric aerosol layer (SAL) state over the last 30 years. The longest time series of the SAL lidar measurements have been accumulated at the Mauna Loa Observatory (Hawaii) since 1973, the NASA Langley Research Center (Hampton, Virginia) since 1974, and Garmisch-Partenkirchen (Germany) since 1976. The fourth lidar station we present started to perform routine observations of the SAL parameters in Tomsk (56.48° N, 85.05° E, Western Siberia, Russia) in 1986. In this paper, we mainly focus on and discuss the stratospheric background period from 2000 to 2005 and the causes of the SAL perturbations over Tomsk in the 2006–2015 period. During the last decade, volcanic aerosol plumes from tropical Mt. Manam, Soufrière Hills, Rabaul, Merapi, Nabro, and Kelut and extratropical (northern) Mt. Okmok, Kasatochi, Redoubt, Sarychev Peak, Eyjafjallajökull, and Grímsvötn were detected in the stratosphere over Tomsk. When it was possible, we used the NOAA HYSPLIT trajectory model to assign aerosol layers observed over Tomsk to the corresponding volcanic eruptions. The trajectory analysis highlighted some surprising results. For example, in the cases of the Okmok, Kasatochi, and Eyjafjallajökull eruptions, the HYSPLIT air mass backward trajectories, started from altitudes of aerosol layers detected over Tomsk with a lidar, passed over these volcanoes on their eruption days at altitudes higher than the maximum plume altitudes given by the Smithsonian Institution Global Volcanism Program. An explanation of these facts is suggested. The role of both tropical and northern volcanic eruptions in volcanogenic aerosol loading of the midlatitude stratosphere is also discussed. In addition to volcanoes, we considered other possible causes of the SAL perturbations over Tomsk, i.e., the polar stratospheric cloud (PSC) events and smoke plumes from strong forest fires. At least two PSC events were detected in 1995 and 2007. We also make an assumption that the Kelut volcanic eruption (Indonesia, February 2014) could be the cause of the SAL perturbations over Tomsk during the first quarter of 2015.

Satellite‐based global volcanic SO2 emissions and sulfate direct radiative forcing during 2005–2012

AbstractAn 8 year volcanic SO2 emission inventory for 2005–2012 is obtained based on satellite measurements of SO2 from OMI (Ozone Monitoring Instrument) and ancillary information from the Global Volcanism Program. It includes contributions from global volcanic eruptions and from eight persistently degassing volcanoes in the tropics. It shows significant differences in the estimate of SO2 amount and injection height for medium to large volcanic eruptions as compared to the counterparts in the existing volcanic SO2 database. Emissions from Nyamuragira (DR Congo) in November 2006 and Grímsvötn (Iceland) in May 2011 that were not included in the Intergovernmental Panel on Climate Change 5 (IPCC) inventory are included here. Using the updated emissions, the volcanic sulfate (SO42−) distribution is simulated with the global transport model Goddard Earth Observing System (GEOS)‐Chem. The simulated time series of sulfate aerosol optical depth (AOD) above 10 km captures every eruptive volcanic sulfate perturbation with a similar magnitude to that measured by Cloud‐Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO). The 8 year average contribution of eruptive SO42− to total SO42− loading above 10 km is ~10% over most areas of the Northern Hemisphere, with a maxima of 30% in the tropics where the anthropogenic emissions are relatively smaller. The persistently degassing volcanic SO42− in the tropics barely reaches above 10 km, but in the lower atmosphere it is regionally dominant (60%+ in terms of mass) over Hawaii and other oceanic areas northeast of Australia. Although the 7 year average (2005–2011) of eruptive volcanic sulfate forcing of −0.10 W m−2 in this study is comparable to that in the 2013 IPCC report (−0.09 W m−2), significant discrepancies exist for each year. Our simulations also imply that the radiative forcing per unit AOD for volcanic eruptions can vary from −40 to −80 W m−2, much higher than the −25 W m−2 implied in the IPCC calculations. In terms of sulfate forcing efficiency with respect to SO2 emission, eruptive volcanic sulfate is 5 times larger than anthropogenic sulfate. The sulfate forcing efficiency from degassing volcanic sources is close to that of anthropogenic sources. This study highlights the importance of characterizing both volcanic emission amount and injection altitude as well as the key role of satellite observations in maintaining accurate volcanic emissions inventories.

Global overview of the geological hazard exposure and disaster risk awareness at world heritage sites

Abstract Many UNESCO world heritage (WH) properties are exposed to geological hazards, or geohazards, which can turn into disasters if local authorities and site managers are unprepared. This paper analyzes for the first time the estimated exposure to geological hazards at 981 world heritage properties worldwide and the risk awareness of their managers. Initially the physical exposure of world heritage properties to four main geological hazards – tsunamis, landslides, earthquakes and volcanic eruptions – was estimated using open-access data from the global risk data platform and global volcanism program. Then, the periodic reporting registered data, which is part of the world heritage monitoring system and includes questions on the hazards that threaten each site, was examined to estimate world heritage site managers’ risk awareness. Finally, estimated and registered datasets enabled to identify focus groups of WH sites exposed to geological hazards worldwide. Results showed that a range of 39% (according open-access data) to 46% (according site managers) of world heritage properties are exposed to at least one of the four aforementioned geological hazards. When considering results from both datasets, the number of WH sites exposed to geohazards raise to 60%. The most frequent natural hazards affecting world heritage properties are earthquakes and landslides, whereas volcanic eruptions and tsunamis are less frequent. The most vulnerable regions are Asia and the Pacific and Latin America and the Caribbean, where more than half of the sites are exposed to at least one of geohazard. Furthermore, the analysis of 41 selected sites, based on real hazardous events, demonstrated that 38 out of 41 (92.7%) geohazard events were identified by one or the other dataset. The quality of the geohazard detection is less significant when both datasets are considered: only 22 out of 41 (53.7%) disaster cases were correctly estimated by both GRPD-GVP and PR-II databases. This difference could be due to the actual vulnerability of the sites, associated to their physical and social characteristics, and their environment, as well as coarse resolution of the open-access data, or to a lack of awareness – on the part of site managers – of the actual disaster risks associated with the hazard(s) affecting their properties. In order to obtain the global vision on the exposure to geohazards, it would be beneficial to combine these two types of information and consider them as complimentary. Moreover, analyzing real vulnerability and management systems at regional and local levels is indispensable to assess the actual degree of disaster risk affecting world heritage properties and define priorities for disaster management interventions.

Spatial and temporal distribution of large volcanic eruptions from 1750 to 2010

Using the dataset provided by the Smithsonian Institution’s Global Volcanism Program, we have extracted the large volcanic eruptions (volcanic explosivity index ⩾ 4) from the period 1750–2010 and have then analyzed the main characteristics of large volcanic eruptions since 1750 according to their geographic latitudes, their elevations, and the years and months in which they occurred. The results show that most large volcanic eruptions were located around the margins of the Pacific Ocean and the islands of Sumatra and Java, especially in the equatorial regions (10°N-10°S). Large volcanic eruptions were concentrated at 1000–2000 m elevations and in the months of January and April. There were more eruptions in the summer half-year (from April to September) than in the winter half-year (from October to the next March). Large volcanic eruptions have interdecadal fluctuations, including cycles of 15–25 years and 35–50 years, which were detected by Morlet wavelet analysis, with the fluctuations being more frequent after 1870 than before. During the periods 1750–1760, 1776–1795, 1811–1830, 1871–1890, 1911–1920 and 1981–1995, there were relatively many large volcanic eruptions.

A global database of composite volcano morphometry

We present a global database on the subaerial morphometry of composite volcanoes. Data was extracted from the 90-m resolution Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM). The 759 volcanoes included in the database are the composite (i.e., polygenetic) volcanoes listed in the Smithsonian Institution Global Volcanism Program (GVP) database that are covered by the SRTM DEM, have a constructional topography and a basal width larger than 2 km. The extent of each volcano edifice was defined using the NETVOLC algorithm, which computes outlines by minimizing a cost function based on breaks in slope around the edifices. Morphometric parameters were then calculated using the MORVOLC algorithm. The parameters characterize and quantify volcano size (basal width, summit width, height, and volume), profile shape (height/basal width and summit width/basal width ratios), plan shape (ellipticity and irregularity indexes), and slopes. In addition, 104 well-defined and relatively large summit craters/calderas were manually delineated and specific parameters were computed. Most parameters show large variation without clear separations, indicating a continuum of volcano morphologies. Large overlap between the main GVP morphologic types highlights the need for a more rigorous quantitative classification of volcano morphology. The database will be maintained and updated through a website under construction.