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Troll, Valentin R.
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Publications (10 of 152) Show all publications
Troll, V. R., Emeleus, C. H., Nicoll, G. R., Mattsson, T., Ellam, R. M., Donaldson, C. H. & Harris, C. (2019). A large explosive silicic eruption in the British Palaeogene Igneous Province. Scientific Reports, 9, Article ID 494.
Open this publication in new window or tab >>A large explosive silicic eruption in the British Palaeogene Igneous Province
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2019 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 494Article in journal (Refereed) Published
Abstract [en]

Large-volume pyroclastic eruptions are not known from the basalt-dominated British Palaeogene Igneous Province (BPIP), although silicic magmatism is documented from intra-caldera successions in central volcanoes and from small-volume ash-layers in the associated lava fields. Exceptions are the Sgùrr of Eigg (58.7 Ma) and Òigh-sgeir pitchstones in the Inner Hebrides (>30 km apart), which have been conjectured to represent remnants of a single large silicic event. Currently available major element data from these outcrops differ, however, creating a need to test if the two pitchstones are really related. We employ a systematic array of methods ranging from mineralogy to isotope geochemistry and find that samples from the two outcrops display identical mineral textures and compositions, major- and trace elements, and Sr-Nd-Pb-O isotope ratios, supporting that the two outcrops represent a single, formerly extensive, pyroclastic deposit. Available isotope constraints suggest a vent in the Hebridean Terrane and available radiometric ages point to Skye, ~40 km to the North. A reconstructed eruption volume of ≥5km3 DRE is derived, suggesting a VEI 5 event or larger. We therefore argue, contrary to long-held perception, that large-volume silicic volcanism and its associated climatic effects were likely integral to the BPIP during the opening of the North Atlantic.

National Category
Geology
Research subject
Earth Science with specialization in Mineral Chemistry, Petrology and Tectonics
Identifiers
urn:nbn:se:uu:diva-366704 (URN)10.1038/s41598-018-35855-w (DOI)000456553400060 ()30679443 (PubMedID)
Available from: 2019-01-24 Created: 2019-01-24 Last updated: 2019-02-12Bibliographically approved
Di Baldassarre, G., Nohrstedt, D., Mård, J., Burchardt, S., Albin, C., Bondesson, S., . . . Parker, C. F. (2018). An Integrative Research Framework to Unravel the Interplay of Natural Hazards and Vulnerabilities. Earth's Future, 6(3), 305-310
Open this publication in new window or tab >>An Integrative Research Framework to Unravel the Interplay of Natural Hazards and Vulnerabilities
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2018 (English)In: Earth's Future, ISSN 1384-5160, E-ISSN 2328-4277, Vol. 6, no 3, p. 305-310Article in journal (Refereed) Published
Abstract [en]

Climate change, globalization, urbanization, social isolation, and increased interconnectedness between physical, human, and technological systems pose major challenges to disaster risk reduction (DRR). Subsequently, economic losses caused by natural hazards are increasing in many regions of the world, despite scientific progress, persistent policy action, and international cooperation. We argue that these dramatic figures call for novel scientific approaches and new types of data collection to integrate the two main approaches that still dominate the science underpinning DRR: the hazard paradigm and the vulnerability paradigm. Building from these two approaches, here we propose a research framework that specifies the scope of enquiry, concepts, and general relations among phenomena. We then discuss the essential steps to advance systematic empirical research and evidence-based DRR policy action. Plain Language Summary The recent deadly earthquake in Iran-Iraq has been yet another reminder of the topicality of natural hazards, and it has come just after an unprecedented series of catastrophic events, including the extensive flooding in South Asia and the string of devastating hurricanes in the Americas. He we identify three main puzzles in the nexus of natural hazards and vulnerabilities, and demonstrate how novel approaches are needed to solve them with reference to a flood risk example. Specifically, we show how a new research framework can guide systematic data collections to advance the fundamental understanding of socionatural interactions, which is an essential step to improve the development of policies for disaster risk reduction.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
Disaster risk reduction, Natural hazards, Vulnerability, Flood risk, Socio-hydrology
National Category
Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-350188 (URN)10.1002/2017EF000764 (DOI)000430171600002 ()
Available from: 2018-05-07 Created: 2018-05-07 Last updated: 2018-06-18Bibliographically approved
Berg, S., Troll, V. R., Harris, C., Deegan, F., Riishuus, M. S., Burchardt, S. & Krumbholz, M. (2018). Exceptionally high whole-rock delta O-18 values in intra-caldera rhyolites from Northeast Iceland. Mineralogical magazine, 82(5), 1147-1168
Open this publication in new window or tab >>Exceptionally high whole-rock delta O-18 values in intra-caldera rhyolites from Northeast Iceland
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2018 (English)In: Mineralogical magazine, ISSN 0026-461X, E-ISSN 1471-8022, Vol. 82, no 5, p. 1147-1168Article in journal (Refereed) Published
Abstract [en]

The Icelandic crust is characterized by low delta O-18 values that originate from pervasive high-temperature hydrothermal alteration by O-18-depleted meteoric waters. Igneous rocks in Iceland with delta O-18 values significantly higher than unaltered oceanic crust (similar to 5.7 parts per thousand) are therefore rare. Here we report on rhyolitic intra-caldera samples from a cluster of Neogene central volcanoes in Borgarfjorour Eystri, Northeast Iceland, that show whole-rock delta O-18 values between +2.9 and +17.6 parts per thousand (n = 6), placing them among the highest delta O-18 values thus far recorded for Iceland. Extra-caldera rhyolite samples from the region, in turn, show delta O-18 whole-rock values between +3.7 and +7.8 parts per thousand (n = 6), consistent with the range of previously reported Icelandic rhyolites. Feldspar in the intra-caldera samples (n = 4) show delta O-18 values between +4.9 and +18.7 parts per thousand, whereas pyroxene (n = 4) shows overall low delta O-18 values of +4.0 to +4.2 parts per thousand, consistent with regional rhyolite values. In combination with the evidence from mineralogy and rock H2O contents, the high whole-rock delta O-18 values of the intra-caldera rhyolites appear to be the result of pervasive isotopic exchange during subsolidus hydrothermal alteration with O-18-enriched water. This alteration conceivably occurred in a near-surface hot spring environment at the distal end of an intra-caldera hydrothermal system. and was probably fed by waters that had already undergone significant isotope exchange with the country rock. Alternatively, O-18-enriched alteration fluids may have been produced during evaporation and boiling of standing water in former caldera lakes, which then interacted with the intra-caldera rock suites. Irrespective of the exact exchange processes involved, a previously unrecognized and highly localized delta O-18-enriched rock composition exists on Iceland and thus probably within the Icelandic crust too.

Place, publisher, year, edition, pages
MINERALOGICAL SOC, 2018
Keywords
Northeast Iceland, high(18)O values, hydrothermal alteration, intra-caldera lakes
National Category
Geology
Identifiers
urn:nbn:se:uu:diva-372902 (URN)10.1180/mgm.2018.114 (DOI)000452016700011 ()
Funder
Swedish Research CouncilThe Royal Swedish Academy of Sciences
Available from: 2019-01-11 Created: 2019-01-11 Last updated: 2019-01-11Bibliographically approved
Geiger, H., Troll, V. R., Jolis, E. M., Deegan, F. M., Harris, C., Hilton, D. R. & Freda, C. (2018). Multi-level magma plumbing at Agung and Batur volcanoes increases risk of hazardous eruptions. Scientific Reports, 8, Article ID 10547.
Open this publication in new window or tab >>Multi-level magma plumbing at Agung and Batur volcanoes increases risk of hazardous eruptions
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2018 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 10547Article in journal (Refereed) Published
Abstract [en]

The island of Bali in Indonesia is home to two active stratovolcanoes, Agung and Batur, but relatively little is known of their underlying magma plumbing systems. Here we define magma storage depths and isotopic evolution of the 1963 and 1974 eruptions using mineral-melt equilibrium thermobarometry and oxygen and helium isotopes in mineral separates. Olivine crystallised from a primitive magma and has average delta O-18 values of 4.8%. Clinopyroxene records magma storage at the crust-mantle boundary, and displays mantle-like isotope values for Helium (8.62 R-A) and delta O-18 (5.0-5.8%). Plagioclase reveals crystallisation in upper crustal storage reservoirs and shows delta O-18 values of 5.5-6.4%. Our new thermobarometry and isotope data thus corroborate earlier seismic and InSAR studies that inferred upper crustal magma storage in the region. This type of multi-level plumbing architecture could drive replenishing magma to rapid volatile saturation, thus increasing the likelihood of explosive eruptions and the consequent hazard potential for the population of Bali.

Place, publisher, year, edition, pages
NATURE PUBLISHING GROUP, 2018
National Category
Geochemistry Geology
Identifiers
urn:nbn:se:uu:diva-361269 (URN)10.1038/s41598-018-28125-2 (DOI)000438343600057 ()30002471 (PubMedID)
Funder
Swedish Research CouncilThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT), SA2015-6212
Available from: 2018-10-05 Created: 2018-10-05 Last updated: 2018-10-05Bibliographically approved
Darmawan, H., Walter, T. R., Troll, V. R. & Budi-Santoso, A. (2018). Structural weakening of the Merapi dome identified by drone photogrammetry after the 2010 eruption. Natural hazards and earth system sciences, 18(12), 3267-3281
Open this publication in new window or tab >>Structural weakening of the Merapi dome identified by drone photogrammetry after the 2010 eruption
2018 (English)In: Natural hazards and earth system sciences, ISSN 1561-8633, E-ISSN 1684-9981, Vol. 18, no 12, p. 3267-3281Article in journal (Refereed) Published
Abstract [en]

Lava domes are subjected to structural weakening that can lead to gravitational collapse and produce pyroclastic flows that may travel up to several kilometers from a volcano's summit. At Merapi volcano, Indonesia, pyroclastic flows are a major hazard, frequently causing high numbers of casualties. After the Volcanic Explosivity Index 4 eruption in 2010, a new lava dome developed on Merapi volcano and was structurally destabilized by six steam-driven explosions between 2012 and 2014. Previous studies revealed that the explosions produced elongated open fissures and a delineated block in the southern dome sector. Here, we investigated the geomorphology, structures, thermal fingerprint, alteration mapping and hazard potential of the Merapi lava dome by using drone-based geomorphologic data and forward-looking thermal infrared images The block on the southern dome of Merapi is delineated by a horseshoe-shaped structure with a maximum depth of 8 m and it is located on the unbuttressed southern steep flank. We identify intense thermal, fumarole and hydrothermal alteration activities along this horseshoe-shaped structure. We conjecture that hydrothermal alteration may weaken the horseshoe-shaped structure, which then may develop into a failure plane that can lead to gravitational collapse. To test this instability hypothesis, we calculated the factor of safety and ran a numerical model of block-and-ash flow using Titan2D. Results of the factor of safety analysis confirm that intense rainfall events may reduce the internal friction and thus gradually destabilize the dome. The titan2D model suggests that a hypothetical gravitational collapse of the delineated unstable dome sector may travel southward for up to 4 km. This study highlights the relevance of gradual structural weakening of lava domes, which can influence the development fumaroles and hydrothermal alteration activities of cooling lava domes for years after initial emplacement.

National Category
Geology
Identifiers
urn:nbn:se:uu:diva-372936 (URN)10.5194/nhess-18-3267-2018 (DOI)000452863800002 ()
Funder
EU, Horizon 2020, ERC-CoG 646858Swedish Research Council
Available from: 2019-01-10 Created: 2019-01-10 Last updated: 2019-01-10Bibliographically approved
Cooper, M. R., Troll, V. R. & Lemon, K. (2018). The "Clay-with-Flints' deposit in Northern Ireland: reassessment of the evidence for an early Paleocene ignimbrite. Geological Magazine, 155(8), 1811-1820
Open this publication in new window or tab >>The "Clay-with-Flints' deposit in Northern Ireland: reassessment of the evidence for an early Paleocene ignimbrite
2018 (English)In: Geological Magazine, ISSN 0016-7568, E-ISSN 1469-5081, Vol. 155, no 8, p. 1811-1820Article in journal (Refereed) Published
Abstract [en]

Reassessment of key geological sections, field relationships and petrographical characteristics of the Northern Ireland Clay-with-Flints' and Donald's Hill Ignimbrite Formation' show they formed dominantly by sedimentary processes. The involvement of a previously postulated pyroclastic flow during early Paleocene time is not recognized and, as such, the Donald's Hill Ignimbrite Formation stratigraphic term is discounted. Instead a multistage model of formation by sedimentary accumulation and remobilization is presented and the term Clay-with-Flints is retained. Regionally, two dominant facies are recognized in most Clay-with-Flints sections. Facies 1 was formed by an initial accumulation of flints on a chalk landscape undergoing karstification, and involved deposition of a clay matrix derived predominantly from contemporaneous erosion of subtropical soil horizons formed mainly on basalt. In Facies 2, evidence is observed for widespread remobilization of Facies 1 deposits by high-density mudflows driven by the advancement of the Antrim Lava Group, which caused the blockage of subsurface and marginalization of surface drainage. A stratigraphical constraint imposed by the presence of a supposed ignimbrite in this part of the North Atlantic Igneous Province has been problematic, but this is resolved by its identification as a diachronous, sedimentary deposit that formed until buried by either the lower or upper formations of the Antrim Lava Group.

Place, publisher, year, edition, pages
CAMBRIDGE UNIV PRESS, 2018
Keywords
"Clay-with-Flints', ignimbrite, Paleocene, stratigraphy
National Category
Geology
Identifiers
urn:nbn:se:uu:diva-363200 (URN)10.1017/S0016756817000760 (DOI)000445338400011 ()
Funder
Swedish Research Council
Available from: 2018-10-18 Created: 2018-10-18 Last updated: 2018-10-18Bibliographically approved
Peters, S. T. M., Troll, V. R., Weis, F. A., Dallai, L., Chadwick, J. P. & Schulz, B. (2017). Amphibole megacrysts as a probe into the deep plumbing system of Merapi volcano, Central Java, Indonesia. Contributions to Mineralogy and Petrology, 172(4), Article ID 16.
Open this publication in new window or tab >>Amphibole megacrysts as a probe into the deep plumbing system of Merapi volcano, Central Java, Indonesia
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2017 (English)In: Contributions to Mineralogy and Petrology, ISSN 0010-7999, E-ISSN 1432-0967, Vol. 172, no 4, article id 16Article in journal (Refereed) Published
Abstract [en]

Amphibole has been discussed to potentially represent an important phase during early chemical evolution of arc magmas, but is not commonly observed in eruptive arc rocks. Here, we present an in-depth study of metastable calcic amphibole megacrysts in basaltic andesites of Merapi volcano, Indonesia. Radiogenic Sr and Nd isotope compositions of the amphibole megacrysts overlap with the host rock range, indicating that they represent antecrysts to the host magmas rather than xenocrysts. Amphibolebased barometry suggests that the megacrysts crystallised at pressures of >500 MPa, i.e., in the mid-to lower crust beneath Merapi. Rare-earth element concentrations, in turn, require the absence of magmatic garnet in the Merapi feeding system and, therefore, place an uppermost limit for the pressure of amphibole crystallisation at ca. 800 MPa. The host magmas of the megacrysts seem to have fractionated significant amounts of amphibole and/or clinopyroxene, because of their low Dy/Yb ratios relative to the estimated compositions of the parent magmas to the megacrysts. The megacrysts' parent magmas at depth may thus have evolved by amphibole fractionation, in line with apparently coupled variations of trace element ratios in the megacrysts, such as e.g., decreasing Zr/Hf with Dy/Yb. Moreover, the Th/U ratios of the amphibole megacrysts decrease with increasing Dy/Yb and are lower than Th/U ratios in the basaltic andesite host rocks. Uranium in the megacrysts' parent magmas, therefore, may have occurred predominantly in the tetravalent state, suggesting that magmatic fO(2) in the Merapi plumbing system increased from below the FMQ buffer in the mid-to-lower crust to 0.6-2.2 log units above it in the near surface environment. In addition, some of the amphibole megacrysts experienced dehydrogenation (H-2 loss) and/or dehydration (H2O loss), as recorded by their variable H2O contents and D/H and Fe3+/Fe2+ ratios, and the release of these volatile species into the shallow plumbing system may facilitate Merapi's often erratic eruptive behaviour.

Place, publisher, year, edition, pages
SPRINGER, 2017
Keywords
Magmatic differentiation, Rare-earth elements, Arc magmas, Barometry, Dehydrogenation, Dehydration
National Category
Geophysics Geochemistry
Identifiers
urn:nbn:se:uu:diva-321335 (URN)10.1007/s00410-017-1338-0 (DOI)000397978000002 ()
Funder
Swedish Research Council
Available from: 2017-05-31 Created: 2017-05-31 Last updated: 2017-05-31Bibliographically approved
Waight, T. E., Troll, V. R., Gamble, J. A., Price, R. C. & Chadwick, J. P. (2017). Hf isotope evidence for variable slab input and crustal addition in basalts and andesites of the Taupo Volcanic Zone, New Zealand. Lithos, 284-285, 222-236
Open this publication in new window or tab >>Hf isotope evidence for variable slab input and crustal addition in basalts and andesites of the Taupo Volcanic Zone, New Zealand
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2017 (English)In: Lithos, ISSN 0024-4937, E-ISSN 1872-6143, Vol. 284-285, p. 222-236Article in journal (Refereed) Published
Abstract [en]

Crustal contamination complicates the identification of primary mantle-derived magma compositions in continental arcs. However, when crustal processes and components are well characterised, it is possible to extrapolate through continental arc magma compositional arrays towards the Hf and Nd isotope compositions of uncontaminated primary magmas. This is because of the similar behaviour of Hf and Nd during fractional crystallisation and mantle melting, and the subsequent limited variation in Hf/Nd in mantle-derived magmas and in many crustal lithologies, resulting in linear contamination trends for Hf-Nd isotopes. Here we present new Hf isotope data for a selection of volcanic rocks and crustal lithologies from the Taupo Volcanic Zone (TVZ), New Zealand and propose that the scatter in Hf-Nd isotopes indicates heterogeneity in the parental magmas prior to interactions with crustal lithologies. The observed variations likely represent variability in primary magma compositions as a result of different degrees of sediment addition at the slab-wedge interface. Coupled variations in isotopic composition, LILE/HFSE ratios (e.g. Rb/Zr and Ba/La) and SiO2 also clearly indicate that shallower level crustal interactions have occurred. Andesites from Ruapehu Volcano have more consistent parental magma compositions, and require greater amounts of a source sediment contribution. Notably, the compositions of older Ruapehu lavas can be modelled by interactions between mantle-derived magmas and lower crustal granulites, whereas younger lavas have probably interacted more with mid- to shallow crustal meta-sedimentary greywacke-argillite lithologies of the Permian to Cretaceous composite Torlesse Terrane. Hf-Nd isotopic compositions of meta-igneous granulite xenoliths from Mt. Ruapehu are consistent with previous interpretations that they are derived from oceanic crust that underlies the Torlesse meta-sediments. The results indicate that interactions with sediments at both the slab-wedge interface and in the lithosphere must be considered when evaluating trace element and isotopic variations in continental arcs.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE BV, 2017
Keywords
Taupo Volcanic Zone, New Zealand, Hf and Nd isotopes, AFC processes, Source addition, Basalt, Andesite
National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-331251 (URN)10.1016/j.lithos.2017.04.009 (DOI)000405252300016 ()
Funder
Swedish Research Council
Available from: 2017-10-24 Created: 2017-10-24 Last updated: 2017-10-24Bibliographically approved
Budd, D. A., Troll, V. R., Deegan, F. M., Jolis, E., Smith, V., Whitehouse, M., . . . Bindeman, I. (2017). Magma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz. Scientific Reports, 7, Article ID 40624.
Open this publication in new window or tab >>Magma reservoir dynamics at Toba caldera, Indonesia, recorded by oxygen isotope zoning in quartz
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2017 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 40624Article in journal (Refereed) Published
Abstract [en]

Quartz is a common phase in high-silica igneous rocks and is resistant to post-eruptive alteration, thus offering a reliable record of magmatic processes in silicic magma systems. Here we employ the 75 ka Toba super-eruption as a case study to show that quartz can resolve late-stage temporal changes in magmatic δ18O values. Overall, Toba quartz crystals exhibit comparatively high δ18O values, up to 10.2‰, due to magma residence within, and assimilation of, local granite basement. However, some 40% of the analysed quartz crystals display a decrease in δ18O values in outermost growth zones compared to their cores, with values as low as 6.7‰ (maximum ∆core−rim = 1.8‰). These lower values are consistent with the limited zircon record available for Toba, and the crystallisation history of Toba quartz traces an influx of a low-δ18O component into the magma reservoir just prior to eruption. Here we argue that this late-stage low-δ18O component is derived from hydrothermally-altered roof material. Our study demonstrates that quartz isotope stratigraphy can resolve magmatic events that may remain undetected by whole-rock or zircon isotope studies, and that assimilation of altered roof material may represent a viable eruption trigger in large Toba-style magmatic systems.

National Category
Geochemistry
Identifiers
urn:nbn:se:uu:diva-316065 (URN)10.1038/srep40624 (DOI)000392659100001 ()28120860 (PubMedID)
Funder
Swedish Research CouncilThe Royal Swedish Academy of Sciences
Available from: 2017-02-24 Created: 2017-02-24 Last updated: 2017-11-29Bibliographically approved
Deegan, F., Troll, V. R., Whitehouse, M. J., Jolis, E. M. & Freda, C. (2016). Boron isotope fractionation in magma via crustal carbonate dissolution. Scientific Reports, 6, Article ID 30774.
Open this publication in new window or tab >>Boron isotope fractionation in magma via crustal carbonate dissolution
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2016 (English)In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, article id 30774Article in journal (Refereed) Published
Abstract [en]

Carbon dioxide released by arc volcanoes is widely considered to originate from the mantle and from subducted sediments. Fluids released from upper arc carbonates, however, have recently been proposed to help modulate arc CO2 fluxes. Here we use boron as a tracer, which substitutes for carbon in limestone, to further investigate crustal carbonate degassing in volcanic arcs. We performed laboratory experiments replicating limestone assimilation into magma at crustal pressure-temperature conditions and analysed boron isotope ratios in the resulting experimental glasses. Limestone dissolution and assimilation generates CaO-enriched glass near the reaction site and a CO2-dominated vapour phase. The CaO-rich glasses have extremely low delta B-11 values down to -41.5%, reflecting preferential partitioning of B-10 into the assimilating melt. Loss of B-11 from the reaction site occurs via the CO2 vapour phase generated during carbonate dissolution, which transports B-11 away from the reaction site as a boron-rich fluid phase. Our results demonstrate the efficacy of boron isotope fractionation during crustal carbonate assimilation and suggest that low delta B-11 melt values in arc magmas could flag shallow-level additions to the subduction cycle.

National Category
Earth and Related Environmental Sciences
Identifiers
urn:nbn:se:uu:diva-302679 (URN)10.1038/srep30774 (DOI)000380873400001 ()27488228 (PubMedID)
Funder
Swedish Research CouncilThe Royal Swedish Academy of SciencesNatural‐Disaster Science
Available from: 2016-09-08 Created: 2016-09-08 Last updated: 2017-11-21Bibliographically approved
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