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The dynamics of phosphorus are intricately governed by geological and ecological processes. Examining phosphorus dynamics in volcanic islands can enhance our comprehension of its behavior within such unique geological systems. However, research on phosphorus dynamics in volcanic islands remains limited. We investigated the phosphorus content of volcaniclastic rocks and basalt soils from Weizhou Island, China, to understand the influencing factors on phosphorus dynamics. The results indicate that in the volcaniclastic profile, phosphorus concentrates at 20–40 cm (17 mg/kg), decreases at 40–60 cm (11.9 mg/kg), and increases at 80–200 cm up to 46.4 mg/kg proximate to the bedrock, for the basalt profile, phosphorus content increases from the surface (80.2 mg/kg) towards the bedrock (83.9 mg/kg). The differences in phosphorus distribution between volcaniclastic rocks and basalts reflect the influence of parent material, rock weathering degree, carbonate content, topographic elevation, sea level changes, and geological activities. A strong positive correlation (R = 0.96907) between total and available phosphorus has been observed, suggesting that total phosphorus content effectively predicts available phosphorus content. Volcaniclastic rocks in wharves and high-elevation areas show low total phosphorus, while forest land with dense vegetation and neutral to alkaline soil supports higher total phosphorus due to enhanced bioavailability for plant absorption and utilization. Overall, the basalt soil of the volcanic island Weizhou Island demonstrates superior long-term fertility compared to the volcaniclastic soil. Despite its low total phosphorus content, it mainly exists in a highly bioavailable form, facilitating plant absorption, which is crucial for enhancing agricultural yields and ecosystem restoration on volcanic islands. [ABSTRACT FROM AUTHOR]

Background: Teide National Park (Canary Islands) is an alpine volcanic ecosystem with shrub vegetation in which legume Spartocytisus supranubius is the most characteristic key species for nitrogen input to the ecosystem. Aims and methods: Bacterial and fungal communities in bulk and rhizosphere soils were analysed through high-throughput sequencing in undisturbed and wildfire-impacted areas to identify key microorganisms in burned and unburned soils. Results: Microbial communities in undisturbed areas exhibited comparable diversity in bulk and rhizosphere soils, but differed in structure and composition. An unusual abundance of non-photosynthetic Chloroflexi from the oligotrotrophic class Ktedonobacteria dominated the bulk soils, surpassing Proteobacteria, Acidobacteria and Actinobacteria. The rhizosphere effect resulted in a microbiome with a more balanced abundance of these four phyla and enriched in potentially plant growth-promoting microorganisms. The impact of a wildfire on the shrub vegetation resulted in a microbial community, especially the fungal community, reduced in diversity and changed in structure and composition, with many of the most characteristic rhizosphere genera becoming vanished, while others took advantage of the postfire conditions and became predominant. Conclusion: The microbial communities of Teide National Park in fire-affected soils, particularly in the rhizosphere environment of the legume shrubland are significantly altered two years after a wildfire, remaining far from unburned scenarios, suggesting a slow recovery in alpine ecosystem with dry volcanic soils. Pseudarthrobacter (Actinobacteria) and Coprinellus (Basidiomycota), the two most fire-favoured genera, are good indicators of fire severity and are proposed as bioindicators to monitor the recovery of the soil ecosystem. [ABSTRACT FROM AUTHOR]

Nabhan, A.; Widinly, N.; Memesh, A.; Khorsheed, M.; El-Sorogy, A.S., and Tawfik, M., 2023. Sedimentological and geomorphological characteristics of Jabal Kudumbul Island, southeast Red Sea, Saudi Arabia. Journal of Coastal Research, 39(6), 1114–1123. Charlotte (North Carolina), ISSN 0749-0208. A marine geological survey of the Quaternary volcanic island of Jabal Kudumbul in the rifted southeastern Red Sea in Saudi Arabia has been conducted for the first time. The survey aimed to document sedimentological and geomorphological characteristics from sample collection and interpretation of high-resolution satellite images taken in the last decade. Beach, sand dune, and sand sheet sedimentary facies types were identified. The volcanic mountain in the western zone of the island and the low-lying sandy shorelines in the eastern zone represent the main geomorphic landforms related to wave and current processes in the study area. The volcanic cone showed three volcano-stratigraphic facies units: basalt rocks, phreatomagmatic lapilli tuff, and vesicular basalt/scoria, indicating that they might have been formed during eruption and interaction between rising magma and shallow seas. The coastline constantly changes over time due to longshore processes and spring tides. A suite of complex wind, wave diffraction, longshore current, and biological processes and episodic synrifting in the area played dominant roles in facies and landscape creation and the overall development of Jabal Kudumbul Island. These findings provide important information for future studies on the arid islands in the Red Sea region beyond modern surficial deposits. [ABSTRACT FROM AUTHOR]

In this paper, we tackle the problem of the intensity attenuation at Ischia, a critical parameter in a high seismic risk area such as this volcanic island. Starting from the new revised catalogue of local earthquakes, we select a dataset of 118 macroseismic observations related to the four main historical events and analyse the characteristics of the intensity attenuation according to both the deterministic and probabilistic approaches, under the assumption of a point seismic source and isotropic decay (circular spreading). In the deterministic analysis, we derive the attenuation law through an empirical model fitting the average values of ΔI (the difference between epicentral intensity I0 and intensities observed at a site IS) versus the epicentral distances by the least-square method. In the probabilistic approach, the distribution of IS conditioned on the epicentre-site distance is given through a binomial-beta model for each class of I0. In the Bayesian framework, the model parameter p is considered as a random variable to which we assign a Beta probability distribution on the basis of our prior belief derived from investigations on the attenuation in Italy. The mode of the binomial distribution is taken as the intensity expected at that site (Iexp). The entire calculation procedure has been implemented in a python plugin for QGIS® software that, given location and I0 (or magnitude) of the earthquake to be simulated, generates a probabilistic seismic scenario according to the deterministic or probabilistic models of attenuation. This tool may be applied in seismic risk analyses at a local scale or in the seismic surveillance to produce real-time intensity shake-maps for this volcanic area. [ABSTRACT FROM AUTHOR]

In May 1965, a main landslide occurred in a deeply incised valley of Piton de la Fournaise volcano, in Réunion Island. This event occurred one day after heavy rainfalls and was consequently interpreted as a mud/debris flow. We take advantage of several sets of historical photographs to reappraise this event. They show that the collapse of a large part of the valley headwall produced a rock flow that dropped 1,740 m and traveled 5,050 m. The surface morphology suggests that the landslide produced a main flow that evolved in a secondary flow in the distal part. The main flow deposit is composed of a matrix‐rich fragmented facies and a jigsaw‐fracturated facies. The matrix presents a gravely‐to‐silty granulometry and fractal dimensions ranging between 2.472 and 2.865. Volumes of the collapsed material (59.7 ± 3.1 Mm3) and the deposit (46 ± 13 Mm3) were determined from a photogrammetric approach. We estimated velocities ranging between 86 and 44 m s−1 along the flow path. Our simulations with SHALTOP reveal that the landslide geometry and velocities are well reproduced with frictional Coulomb rheology. We thus interpret the 1965 Mahavel landslide as a main rock avalanche rather than a mud/debris flow. We propose that the trigger of the 1965 avalanche, and of the smaller events in 1995 and 2001, is the water infiltration related to the intense rainfalls, which systematically preceded by one day each collapse. Finally, the succession of dry and wet years before each collapse event could promote favorable conditions to failure. Plain Language Summary: In 1965, a main landslide occurred in a deeply incised valley of Réunion Island (Indian Ocean). It followed heavy rainfalls and was consequently interpreted as a main mudflow. We used historical photographs, deposit descriptions, and numerical simulations to reappraise this event that fortunately did not have any casualties. We show that about 60 Mm3 of volcanic rocks suddenly collapsed and produced a rock avalanche that traveled over a total distance of 5 km. The flow traveled at velocities ranging between 86 and 44 m s−1. We interpret this landslide as a rock avalanche instead of a mudflow. Our work finally suggests that the annual precipitation variability could be a main conditioning factor that promotes scarp collapses and consequently enhances erosion. The increase of precipitation variability with climate warming could therefore increase the occurrence of large collapses and rock avalanches in mountainous areas. Key Points: We use historical photographs, deposit descriptions, and numerical simulations to reappraise the 1965 Mahavel landslide of Réunion IslandThe collapse of 60 Mm3 of volcanic rocks triggered a large rock avalanche that traveled 5 km at velocities as high as 86 and 44 m s−1Rock avalanches are interpreted as the main process to explain the high long‐term erosion rates of Réunion Island [ABSTRACT FROM AUTHOR]

We applied two machine learning models to detect earthquakes from records observed with seismometers temporarily installed on a volcanic island. The two models are based on different principles: one regards seismic waveforms as images, using a convolutional neural network (CNN) to determine the first arrival times of P-waves, S-waves. The other model regards seismic waveforms as series data. The model processes seismic waveforms as data in a specific order of noise, P-wave, and S-wave, similar to natural language. The purpose of this study is to present the results of using machine learning first arrival times identification models with two principles for noisy seismic waveforms, caused by sea waves and strong winds in volcanic islands, and to evaluate the effectiveness of machine learning models for noisy observation records. We created a Confusion Matrix using first arrival times determined by an expert and evaluated the detection performance of these two models using some metrics of the matrix. Additionally, we assessed accuracy of the model-identified first arrival times by generating a frequency distribution of the difference from the expert's detecting time. The study discovered that the model treating data as series had superior detection ability for noisy data compared to the one treating data as images and the accuracy of the first arrival time detection was also better for the series data model too. We compared the results obtained on this island with those obtained at the permanent station, which is considered to have less noise interference, described in Mousavi et al., 2020. It was found that the difference in detection ability between the two models is slight for data obtained at permanent stations with low noise interference, but that the difference in detection ability between the algorithms of the two models is significant in noisy environments. • Applying 2 machine learning models for detection of earthquakes from noisy data. • 2 models algorism: Series data processing algorism and Image recognition algorism. • 2 model's names: EQ transformer and GPD. • The former one had higher detection ability than the latter in noisy environment. • No big difference in detection ability between the two models to low noisy data. [ABSTRACT FROM AUTHOR]

This paper presents an advanced borehole heat exchanger that has been developed in order to apply a ground source heat pump to a volcanic island where the existing borehole heat exchangers are inapplicable by local ordinance. The advanced borehole heat exchanger was fabricated and installed at a verification-test site to evaluate its heat capacity in terms of refrigeration ton (RT). The proposed heat exchanger was also compared with the conventional heat exchanger that was made of high-density polyethylene (HDPE) heat exchanger. The thermal response test was carried out by flowing water at various temperatures into the heat exchangers at the fixed flow rate of 180 L/min. The results revealed that the maximum heat capacity for the developed heat exchanger was measured at 63.9 kW, which is 160% higher than that of the high-density polyethylene heat exchanger (39.9 kW). It was also found that the developed HX has the highest heat gain achieving 94 kW as compare to 21 kW for high-density polyethylene-Hx.

A high concentration of fluoride in groundwater poses a risk to human health. One of the best-known problems related to excess fluoride in drinking water is dental fluorosis. The characteristic composition of volcanic rocks in oceanic islands tends to present high concentrations of fluoride in groundwater discharge in springs. This study investigates fluoride content in two springs (Encontro and Ferreiros) on the island of Brava (Cape Verde), with the objective of monitoring the operational control production and distribution of drinking water. Using a spectrophotometric method, the level of fluoride found in the water discharged from the Encontro spring was found to be in the range of 4.8 to 6.5 mg/L, whereas at the Ferreiros spring, it was 5.8 to 6.2 mg/L. These results are far above the threshold limit established in the decree No. 5 of 2017 of the Cape Verdean legislation, whose legal threshold value for fluoride is 1.5 mg/L, the same value established by the World Health Organization (WHO). Due to geological conditions and consequences for the health of the population, the water is not adequate for consumption without proper treatment. [ABSTRACT FROM AUTHOR]

Weizhou Island and Xieyang Island are two large and young volcanic sea islands in the northern part of the South China Sea. In this study, high-throughput sequencing (HTS) of 16S rRNA genes was used to explore the diversity of Actinobacteria in the Weizhou and Xieyang Islands. Moreover, a traditional culture-dependent method was utilized to isolate Actinobacteria, and their antibacterial and cytotoxic activities were detected. The alpha diversity indices (ACE metric) of the overall bacterial communities for the larger island (Weizhou) were higher than those for the smaller island (Xieyang). A beta diversity analysis showed a more dispersive pattern of overall bacterial and actinobacterial communities on a larger island (Weizhou). At the order level, Frankiales, Propionibacteriales, Streptomycetales, Micrococcales, Pseudonocardiales, Micromonosporales, Glycomycetales, Corynebacteriales, and Streptosporangiales were the predominant Actinobacteria. A total of 22.7% of the OTUs shared 88%-95% similarity with some known groups. More interestingly, 15 OTUs formed a distinct and most predominant clade, and shared identities of less than 95% with any known families. This is the first report about this unknown group and their 16S rRNA sequences obtained from volcanic soils. A total of 268 actinobacterial strains were isolated by the culturedependent method. Among them, 55 Streptomyces species were isolated, representing that 76.6% of the total. S. variabilis and S. flavogriseus were the most abundant. Moreover, some rare Actinobacteria were isolated. These included Micromonospora spp., Nocardia spp., Amycolatopsis spp., Tsukamurella spp., Mycobacterium spp., and Nonomuraea spp. Among them, eight Streptomyces spp. exhibited antibacterial activity against Bacillus cereus. Only three strains inhibited the growth of Escherichia coli. Four strains showed good activity against aquatic pathogenic bacterial strains of Streptococcus iniae. The cytotoxicity assay results showed that 27 strains (10.07%) exhibited cytotoxic activity against HeLa and A549 cell lines. Many actinobacterial strains with cytotoxic activity were identified as rare Actinobacteria, which illustrated that volcanic islands are vast reservoirs for Actinobacteria with promising antibacterial and cytotoxic activity. This study may significantly improve our understanding of actinobacterial communities on volcanic islands. The isolated Actinobacteria showed promising prospects for future use. [ABSTRACT FROM AUTHOR]

Studies on oceanic island biodiversity have been the foundation for much theoretical work. However, seamounts are mostly underexplored, and little information is available about their potential as stepping stones for oceanic dispersal and their role in diversification. Here we used a genetic approach to test different models of marine dispersal between the continental coast and a volcanic ridge composed of seamounts and oceanic islands. We observed that the stepping stone model best fits our results, with one reef fish species displaying ongoing gene flow and another showing endemic lineages restricted to the islands and most isolated seamounts. The data also suggest that connectivity among remote regions could be influenced by Pleistocene sea level fluctuations and that a widespread genetic lineage was originated from an island endemic. Recent findings on island endemic species showed a similar pattern of both origin and export of genetic lineages, indicating that this process occurred multiple times in the Pleistocene. This study highlights the role of seamounts in supporting subpopulations that, in turn, allow island colonization, diversification, and a biodiversity feedback process that nourishes source populations with evolutionary novelty from peripheral regions. [ABSTRACT FROM AUTHOR]

Abstract Volcanic eruptions are one of the largest natural disturbances and are followed by the establishment of novel plant and animal communities in terrestrial ecosystems. However, the role of pre‐eruption vegetation in the establishment of arthropod communities after volcanic disturbances is currently unknown. Here, we asked whether the legacy of pre‐eruption vegetation mediates the community structure of ground‐dwelling arthropods after volcanic disturbances. The 2015 eruption in Kuchinoerabu‐jima Island, southwest Japan, caused two types of disturbances [a pyroclastic flow and a lahar (i.e., mudflow)] in three types of forests (broad‐leaved, black pine, and cedar). We hypothesized that pre‐eruption vegetation would influence the community structure of ground‐dwelling arthropods after the disturbance, and we expected that these effects from vegetation would be more prevalent for the less severe disturbances. The total abundance of ground‐dwelling arthropods decreased more in the lahar than the pyroclastic flow, and arthropod species composition showed a greater change after the lahar. These findings suggest that the lahar disturbance was more severe than the pyroclastic disturbance. Contrary to expectations, the difference in the arthropod species composition among the vegetation types was greatest after the lahar. After the pyroclastic flow, leaf litter remained to some degree with all the vegetation types. After the lahar disturbance, however, although the litter in the cedar forests remained, the litter disappeared completely from broad‐leaved and black pine forests. The disappearance of litter from these two forest types after the lahar may be responsible for the greater difference in arthropod species composition among the vegetation types. This study shows that the legacy effects of pre‐eruption vegetation on terrestrial arthropod communities after volcanic disturbance were different depending on the type of disturbance. Focusing on the role of pre‐eruption biotic factors would contribute to a better understanding of the recovery processes of terrestrial ecosystems after large natural disturbances.

Surtsey, a young basaltic island off the south coast of Iceland, was built by volcanic activity in 1963–1967 from a pre-eruption oceanic seafloor depth of 130 m. An aeromagnetic survey was carried out in October 2021 over a 60 km2 area covering Surtsey and its surroundings. It aimed to explore the internal structure and the possible existence of basaltic intrusions associated with the five vents active at different times over the 3.5 years of eruptive activity. The survey line spacing was 200 m and the flying altitude was generally 90 m a.s.l. The strongest anomalies (amplitude ∼700 nT) are caused by the 30–100 m thick subaerially erupted lava field on the southern part of Surtsey, formed in two episodes of effusive activity:1964–1965 and 1966–1967. 2D spectral analysis and Euler deconvolution indicate that the causative bodies of anomalies outside the island of Surtsey are located within the uppermost 300 m of the seafloor and their horizontal dimensions are similar to or smaller than their depth. 3D forward modeling of the island and its surroundings, constrained by observations during the formation of the island and drill cores extracted in 1979 and 2017, is consistent with an absence, at all vents, of pillow lava and therefore effusive activity in their opening phases. However, the data support the existence of a 10–20 m thick pillow lava field on the seafloor, 2.5–3 km2 in area, extending about ∼1 km to the south of Surtsey. The field is considered to have been fed by magma reaching the seafloor via channelized intrusive flow through the foreset breccia constituting the submarine part of an emerging lava delta during the early stage of effusive eruption in May–July 1964. The general scarcity of significant magnetic bodies within the edifices is consistent with magma fragmentation dominating the submarine eruptions from the onset of activity. A small magnetic anomaly is observed over the submarine edifice of Surtla, built during short-lived activity over ∼10 days in 1963–1964. This anomaly is consistent with observed subaqueous weak or moderate explosive activity that may have allowed a dyke to be preserved within the submarine tephra mound. More violent Surtseyan activity was observed at other vents, however, and may have destroyed any initial dykes that, if preserved, might have been resolved magnetically. Indications of magnetized volcanic rocks of unknown age predating the Surtsey eruption are found beneath the flank of the ephemeral island of Jólnir, the southernmost of the Surtsey vents. [ABSTRACT FROM AUTHOR]

Visconti, G.; Scopelliti, G.; Caldareri, F.; Agate, M.; Cambera, I.; Sulli, A., and Arculeo, M., 2022. Hatching success of Caretta caretta on a Mediterranean volcanic beach: Impacts from environmental parameters and substrate composition. Journal of Coastal Research, 38(3), 603–612. Coconut Creek (Florida), ISSN 0749-0208. New data on the potential impact of environmental parameters and the mineralogical nature of the substrate on the hatching success of the loggerhead sea turtle Caretta caretta on a volcanic beach on Linosa Island in the central Mediterranean Sea are reported. During 2 years of investigation (2018–19), five nests were observed. The temperature and moisture of the nests were determined along with the grain size and mineralogical nature of the substrate. The temperature values of the nests recorded at depths of 5 and 35 cm showed an average temperature incubation of 32.2°C ± 1.4°C and 32.8°C ± 1.6°C, respectively, with peaks close to 37°C. The sedimentological analysis carried out on two cores revealed the prevalence of large sandy particle and sediment moisture of about 35% in the deeper layers. A total of 214 laid eggs were recorded in 2018 with only 44 emerged turtles, whereas 45 turtles emerged from 199 laid eggs in 2019. Both years showed a low hatching success (25%–30%) and a high frequency of anomalies (>60%), which were present in individuals as nonmodal scutes or bifid limbs. Results suggest that environmental parameters such as temperature, sand moisture, and the geological nature of the substrate seem to play an important role in the reproductive success of this species. Some aspects for improving the nesting site and egg development conditions are also discussed. [ABSTRACT FROM AUTHOR]

Study region: Water resource management relies fundamentally on our ability to monitor climate forcing variability, especially in tropical mountainous environment where the temporal and spatial variability of rainfall strongly controls the dynamics of the water resource. In West Java Island, rainfall temporal and spatial distribution significantly varies in function of regional climatology and volcanoes morphology while accessibility issues and the complexity of climatic phenomena notably are limitations for reliable rainfall ground instrumentation. Study focus: Here, we assess the ability of climate reanalyses (CHELSA and TerraClimate) and satellite products (CHIRPS) in capturing rainfall high resolution spatial variability. The accuracy of rainfall amounts, variability and dynamics of each global product is estimated using the three component of Kling-Gupta efficiency score. As direct statistical comparison is influenced by resolution issues, our approach is completed by a process-based one. The spatial and orographic rainfall patterns of the global products are analyzed according to known climatic phenomena. Hydrological Insights: It appears that, TerraClimate provides the most accurate and stable estimation for temporal monitoring. CHIRPS shows consistent rainfall patterns with atmospheric circulation and volcanoes morphology but overestimates overall rainfall amounts. This study presents a methodology for assessing global climatic products over poorly instrumented areas. The results demonstrate that high resolution global products are somewhat interesting for water resources management. However, several temporal and spatial biases still limit their integration for operational purposes.

Gamalama is an active stratovolcano on Ternate, a small volcanic island in Maluku Utara, Indonesia. Since 1510, a total of 77 eruptions have been recorded, with various impacts on the population and environment on the island and its surroundings. In July 2015, Gamalama erupted after < 24 h of precursor signs. The seismic activity continued to increase until September 2015, as marked by three sudden eruptions that were not preceded by significant volcanic and tremor earthquakes. This research was intended to understand the chronology and impact of the 2015 Gamalama eruption, which is categorically unusual, and to learn how the government conducted relevant crisis management and in what manners the community affected by ejected materials reacted to it. The former was achieved by analyzing the data provided by the Gamalama volcano observatory. As for the latter, interviews with key stakeholders in volcanic disaster management and a questionnaire-based survey involving 85 respondents in the most affected areas were conducted. The results showed that despite the relatively small Volcanic Explosivity Index (VEI = 2), the 2015 eruption was rather unexpected to many parties because it began with a short-term precursor sign (less than a day). The impact included tephra deposits as thick as 2–6 mm was in the Loto, Togafo, and Takome Villages. A total of 1791 people was recorded evacuating to several locations, such as Afe Taduma village, the SMKN 2 camp, the SKB camp, and the Naval Base camp. After a rapid impact assessment and coordination with the Center for Volcanology and Geological Hazard Mitigation (CVGHM), the government issued a status of emergency and evacuation orders. In cases when eruptions are initiated with a short-term precursor, the large population size and geographic condition of Ternate Island create a particular challenge in the resultant evacuation. Nevertheless, with prior mitigation measures and evacuation drills in hazard zones, evacuation can be carried out effectively. Even when a large-scale Gamalama eruption requires an evacuation to neighboring islands, a properly implemented mitigation such as the establishment of sister islands can substantially facilitate volcanic crisis management activities on small islands. [ABSTRACT FROM AUTHOR]

Three Holocene tufas from Gran Canaria volcanic island were studied with the aim of deciphering their sedimentary evolution through space and time. Las Temisas tufa (south‐eastern arid part of the island) is dominantly composed of oncoids, intraclasts, phytoclasts, coated stems, minor thin stromatolites, and a high amount of siliciclastics. It was deposited in a fluvial system with variable flow velocities and palustrine conditions areas, which alternated with high energy events. Azuaje tufa (northern humid part of the island) is composed of coated stems, stromatolites, oncoids and phytoclasts, with relatively low amounts of siliciclastics, suggesting slow‐flowing and palustrine conditions and a relatively low incidence of (high energy) floodings. Los Berrazales tufa (north‐west of Gran Ganaria, the most humid one), is mainly composed of coated stems and crystalline crusts, formed in a laminar flow regime. Dominant clastic sedimentation in Las Temisas and high calcite growth rates in Los Berrazales led to a poor development of stromatolites in comparison with Azuaje. Las Temisas and Azuaje deposits have similar upward evolution with decreasing trend in siliciclastics and increasing trend in carbonates. However, Las Temisas has higher siliciclastic and lower phytoclastic contents suggesting a less vegetated area and more arid climate than in the other deposits. Additionally, tufas record local events common in volcanic terrains. Azuaje presents three units bounded by erosive discontinuities, which reveal significant erosion by enhanced runoff that could be caused by loss of vegetation due to wildfires related to volcanic eruptions at headwaters. Las Temisas record a possible interruption in sedimentation represented by aligned boulders due to rockfalls from the hillsides. These deposits formed from waters with similar chemistry providing to the carbonates their similar signals in δ13C–δ18O stable isotopes and 87Sr/86Sr ratios like that of the volcanic rocks. This work shows how, in volcanic areas, tufas are unique archives of the climate, vegetation and volcanic‐related processes, because all imprint the sedimentary regime of tufa deposition. [ABSTRACT FROM AUTHOR]

Nicotiana glauca it is naturally distributed throughout South America. It was introduced in North America, Europe, Africa, Asia and Oceania and arrived to the Canary Islands as an ornamental plant, where has been invading altered soils. Endophytic fungi are known to produce active compounds that provide protection to their host against diseases and attack of herbivores, these microorganisms being an interesting source of novel molecules. So far, the endophytic fungal communities of Nicotiana have not been studied in the Canary Islands. The goal of this study is to evaluate the diversity of the fungal endophytes community associated with Nicotiana glauca. A total of 36 fungal species were isolated from roots, stems and leaves of plants collected in three locations from Tenerife Island - San Miguel de Abona, Fasnia and Puerto de la Cruz. The highest species richness values were found in leaves and stems (Margalef index = 3.33 and 3.36, respectively) versus roots (Margalef index = 2.52). Simpson's index complements the results of the Margalef index, indicating a fungal community with a high dominance value in roots (D = 0.65) due to the presence of multiple Fusarium species. Fungal community in Fasnia had the highest value of species richness (Margalef index = 3.69 versus 2.17 and 2.27 for San Miguel de Abona and Puerto de la Cruz, respectively). Results indicate fungal specificity to organ and location with 13 genera isolated from a single location and organ, among which rare species like Collariella and Gelasinospora. In this study was detected and isolated for the first time in Canary Islands the fungal species Collariella hilkhuijsenii which is of importance for the ecology of this genus scarcely known. Special attention should be offered to the presence of Fusarium, which possibly relates to the alkaloid production ability of both, the plant and the fungal strains. [ABSTRACT FROM AUTHOR]

The island-forming Nishinoshima eruptions in the Ogasawara Islands, Japan, provide a rare opportunity to examine how the terrestrial part of Earth’s surface increases via volcanism. Here, the sequence of recent eruptive activity of Nishinoshima is described based on long-term geological and geochemical monitoring of eruptive products. Processes of island growth and temporal changes in the magma chemistry are discussed. The growth of Nishinoshima was sustained by the effusion of low-viscosity andesite lava flows since 2013. The lava flows spread radially with numerous branches, resulting in compound lava flows. Lava flows form the coherent base of the new volcanic edifice; however, pyroclastic eruptions further developed the subaerial volcanic edifice. The duration of three consecutive eruptive episodes decreased from 2 years to a week through the entire eruptive sequence, with a decreasing eruptive volume and discharge rate through time. However, the latest, fourth episode was the most intense and largest, with a magma discharge rate on the order of 106 m3/day. The temporal change in the chemical composition of the magma indicates that more mafic magma was involved in the later episodes. The initial andesite magma with ∼60 wt% SiO2 changed to basaltic andesite magma with ∼55 wt% SiO2, including olivine phenocryst, during the last episode. The eruptive behavior and geochemical characteristics suggest that the 2013–2020 Nishinoshima eruption was fueled by magma resulting from the mixing of silicic and mafic components in a shallow reservoir and by magma episodically supplied from deeper reservoirs. The lava effusion and the occasional explosive eruptions, sustained by the discharge of magma caused by the interactions of these multiple magma reservoirs at different depths, contributed to the formation and growth of the new Nishinoshima volcanic island since 2013. Comparisons with several examples of island-forming eruptions in shallow seas indicate that a long-lasting voluminous lava effusion with a discharge rate on the order of at least 104 m3/day (annual average) to 105 m3/day (monthly average) is required for the formation and growth of a new volcanic island with a diameter on km-scale that can survive sea-wave erosion over the years.

Aim: Accounting for geo‐environmental dynamics is crucial to understand community assembly across islands. Whittaker et al. (J Biogeogr, 35:977–994, 2008)'s General Dynamic Model (GDM) aims towards this goal. Yet, it does not explicitly consider that most islands belong to archipelagos. We examined how island biodiversity dynamics are influenced by the interaction of eco‐evolutionary processes acting at the archipelago level with each island's geo‐environmental dynamics. Location: Hypothetical archipelagos. Taxon: Any. Methods: We used an individual‐based model, ecologically neutral within the archipelago. Several islands emerge in succession with a typical volcanic ontogeny. We considered both mainland and inter‐island dispersal. Geographically isolated lineages diverged over time, possibly speciating. Results: We found diversity to be at dynamic equilibrium. In an archipelago, islands hosted more diversity and more endemic species, at both island and archipelago levels, than an equivalently‐sized single isolated island. This was due to an 'archipelago effect': inter‐island dispersal increased within‐island diversity through species occurrence on multiple islands; species may undergo anagenetic changes on the colonised islands, eventually speciating, thereby increasing archipelago diversity. Biodiversity dynamics of different islands may differ even on islands with identical geo‐environmental dynamics because the archipelago effect varied over time and affected each island differently ('history effect'). By accounting for these effects, we predicted detectable deviations from the GDM predictions, which are largest for remote archipelagos, with islands located close together and with an intermediate time of island emergence. In linear stepping‐stone archipelagos, we predicted higher diversity on centrally located islands. Main conclusions: Our results demonstrate that analyses of insular biodiversity data would greatly benefit from explicitly accounting for both archipelago and history effects. We suggest incorporating variables characterising the spatio‐temporal structure of the whole archipelago. We discuss possible difficulties in distinguishing between the archipelago effect and equilibrium diversity dynamics. [ABSTRACT FROM AUTHOR]

Both Savai'i Island and Upolu Island of Samoa are home to numerous potential geosites that could form the basis of geopark projects at a range of scales from local, regional, or global. During the Samoa Geoparks Project Phase 1, intensive research identified Samoa's geoheritage values, resulting in the selection of the island of Savai'i as a location for development of geosite inventories, using a first-order approach to create a scientific basis for future geoheritage, geoconservation, and geotourism ventures. The rationale behind this decision was based on the size of the island; the geodiverse and largely untouched landscapes with high geodiversity values; and superbly exposed young volcanic features that are relatively accessible. Most of these volcanic features derived from Holocene and even historical volcanic activity. Within the potential areas of geosites, volcanic features currently utilized as tourist attractions (mataaga in Samoan) are mostly associated with living cultural activities in terms of traditional stories, myth, and place names. These geoheritage components are a very significant part of the Samoa Geoparks Project in general. Workshop and training for further development of the Samoa Geoparks Project are recommended in this study to co-design and co-develop the geopark concept with local communities working in collaboration with geoscience experts. The role of external geoscientists has been redefined as facilitators of participatory methods using iterative, step-by-step processes, where each facet of the geopark is co-produced through truly inclusive methods and frameworks. [ABSTRACT FROM AUTHOR]

IODP Expedition 340 successfully drilled a series of sites offshore Montserrat, Martinique and Dominica in the Lesser Antilles from March to April 2012. These are among the few drill sites gathered around volcanic islands, and the first scientific drilling of large and likely tsunamigenic volcanic island-arc landslide deposits. These cores provide evidence and tests of previous hypotheses for the composition and origin of those deposits. Sites U1394, U1399, and U1400 that penetrated landslide deposits recovered exclusively seafloor sediment, comprising mainly turbidites and hemipelagic deposits, and lacked debris avalanche deposits. This supports the concepts that i/ volcanic debris avalanches tend to stop at the slope break, and ii/ widespread and voluminous failures of preexisting low-gradient seafloor sediment can be triggered by initial emplacement of material from the volcano. Offshore Martinique (U1399 and 1400), the landslide deposits comprised blocks of parallel strata that were tilted or microfaulted, sometimes separated by intervals of homogenized sediment (intense shearing), while Site U1394 offshore Montserrat penetrated a flat-lying block of intact strata. The most likely mechanism for generating these large-scale seafloor sediment failures appears to be propagation of a decollement from proximal areas loaded and incised by a volcanic debris avalanche. These results have implications for the magnitude of tsunami generation. Under some conditions, volcanic island landslide deposits composed of mainly seafloor sediment will tend to form smaller magnitude tsunamis than equivalent volumes of subaerial block-rich mass flows rapidly entering water. Expedition 340 also successfully drilled sites to access the undisturbed record of eruption fallout layers intercalated with marine sediment which provide an outstanding high-resolution data set to analyze eruption and landslides cycles, improve understanding of magmatic evolution as well as offshore sedimentation processes.

On volcanic islands, the release of animals from predators and competitors can lead to increased body size and population density as well as the expanded habitat use of introduced animals relative to their mainland counterparts. Such alterations might facilitate the spread of diseases on islands when these exotic animals also carry pathogenic agents; however, this has rarely been investigated. The commensal Asian house rat (Rattus tanezumi) is confined to human residential surroundings in mainland Taiwan but can be observed in the forests of nearby Orchid Island, which is a tropical volcanic island. Orchid Island is also a hot spot for scrub typhus, a lethal febrile disease transmitted by larval trombiculid mites (chiggers) that are infected primarily with the rickettsia Orientia tsutsugamushi (OT). We predicted an increase in chigger abundance when rodents (the primary host of chiggers) invade forests from human settlements since soils are largely absent in the latter habitat but necessary for the survival of nymphal and adult mites. A trimonthly rodent survey at 10 sites in three habitats (human residential, grassland, and forest) found only R. tanezumi and showed more R. tanezumi and chiggers in forests than in human residential sites. There was a positive association between rodent and chigger abundance, as well as between rodent body weight and chigger load. Lastly, >95% of chiggers were Leptotrombidium deliense and their OT infection rates were similar among all habitats. Our study demonstrated potentially elevated risks of scrub typhus when this commensal rat species is allowed to invade natural habitats on islands. Additionally, while the success of invasive species can be ascribed to their parasites being left behind, island invaders might instead obtain more parasites if the parasite requires only a single host (e.g., trombiculid mite), is a host generalist (e.g., L. deliense), and is transferred from unsuitable to suitable habitats (i.e., human settlements on the mainland to forests on an island).

Volcanic aquifers supply a substantial portion of water resources in many parts of the world, including islands, and their productivity depends strongly on volcanic stratigraphy, which exhibits considerable heterogeneity. We investigated water inflow to lava tube caves formed from numerous basaltic lava flows in the northeastern coastal area of Jeju Island after storm events and monitored relative inflow rates monthly over 1 year to characterize groundwater flow processes in the upper parts of volcanic aquifers, and to evaluate the applicability of the previous hydrogeological models proposed for the island. Considerable water inflow arose shortly after storms from exposed palaeosol layers on the walls of the caves. The monthly monitoring results showed that wall inflow associated with these palaeosol layers is substantial. In both cases, discharge from ceiling drips was much less and more temporally variable compared to wall inflow discharge. Water flowing into the caves was rapidly drained through the floor at all monitoring sites. The lateral extent of the palaeosol layers was identified using drill core logs near the cave and outcrops in the coastal area. Based on these results, we inferred that multiple perched aquifers are formed by low‐permeability palaeosol layers between lava flows, which are connected by vertical flows at discontinuities in the palaeosol layer, eventually reaching the basal aquifer. This study revealed the water inflow processes observed in lava tube caves constrained by palaeosol layers, and established a hydrogeological conceptual model incorporating multiple perched aquifers in both coastal and mountainous areas associated with extensive palaeosol layers formed during volcanic hiatuses. This finding would help elucidate recharge, groundwater flow, and contaminant transport processes in many volcanic aquifers that are not adequately represented by the previous models, and contribute to better management of groundwater in those areas. [ABSTRACT FROM AUTHOR]

Volcanic eruptions are one of the largest natural disturbances and are followed by the establishment of novel plant and animal communities in terrestrial ecosystems. However, the role of pre‐eruption vegetation in the establishment of arthropod communities after volcanic disturbances is currently unknown. Here, we asked whether the legacy of pre‐eruption vegetation mediates the community structure of ground‐dwelling arthropods after volcanic disturbances. The 2015 eruption in Kuchinoerabu‐jima Island, southwest Japan, caused two types of disturbances [a pyroclastic flow and a lahar (i.e., mudflow)] in three types of forests (broad‐leaved, black pine, and cedar). We hypothesized that pre‐eruption vegetation would influence the community structure of ground‐dwelling arthropods after the disturbance, and we expected that these effects from vegetation would be more prevalent for the less severe disturbances. The total abundance of ground‐dwelling arthropods decreased more in the lahar than the pyroclastic flow, and arthropod species composition showed a greater change after the lahar. These findings suggest that the lahar disturbance was more severe than the pyroclastic disturbance. Contrary to expectations, the difference in the arthropod species composition among the vegetation types was greatest after the lahar. After the pyroclastic flow, leaf litter remained to some degree with all the vegetation types. After the lahar disturbance, however, although the litter in the cedar forests remained, the litter disappeared completely from broad‐leaved and black pine forests. The disappearance of litter from these two forest types after the lahar may be responsible for the greater difference in arthropod species composition among the vegetation types. This study shows that the legacy effects of pre‐eruption vegetation on terrestrial arthropod communities after volcanic disturbance were different depending on the type of disturbance. Focusing on the role of pre‐eruption biotic factors would contribute to a better understanding of the recovery processes of terrestrial ecosystems after large natural disturbances. [ABSTRACT FROM AUTHOR]

This paper presents new bathymetric data acquired around Linosa Island, in the Pelagie Archipelago, revealing the submarine extension of the volcanic edifice, more wide and complex than previously known. The seafloor of Linosa, from the coastal area to about 1000 m depth, was mapped with multibeam systems during the ‘Linosa 2016’ and ‘BioGeoLin 2017’ surveys. A bathymetric map of the surveyed area (about 298 km2) was drawn at the original 1:30,000 scale. Overall, the submarine portions of Linosa extend on a total area of about 159 km2 and are preferentially developed in a NW-SE direction, in agreement with the regional main tectonic trend in the area. The new bathymetric data allow to recognize different sectors in the submarine extension of the volcanic edifice where constructional (volcanic) activity alternates with erosive-depositional processes affecting the submarine flanks of the island.

Heard Island is a subantarctic volcanic island in the southern Indian Ocean and includes Australia's only active volcano, Big Ben (2813 m high, 18 km diameter). The most recent eruption of lava at Big Ben occurred in November 2020. Heard Island is the southernmost subaerial exposure of the Kerguelen Plateau, a mainly submerged large igneous province formed as a result of the activity of the Kerguelen plume over the last 130 Myrs. Using published and unpublished data and reports, modern satellite images, and private and public rock collections, we produced a new geological map of Heard Island supplemented by new 40Ar/39Ar isotopic ages. The volcanoes on Heard Island have been constructed on a ~ 300-m-thick platform of 10–5-Myr-old submarine volcaniclastic rocks known as the Drygalski Formation, now exposed above sea level. The Drygalski Formation is underlain by the Oligocene Laurens Peninsula Limestones. Exposed Big Ben lavas are dominated by basanite, basalt, and trachybasalt compositions. Two Big Ben lavas were dated at 11.1 ± 1.1 ka and 23.9 ± 2.1 ka, expanding the range of ages previously reported for nonhistorical lavas from Big Ben (356 ± 51–33 ± 52 ka). Sector collapse occurred on Big Ben prior to the formation of the current eruptive centre, Mawson Peak (likely after 23 ± 16 ka). Laurens Peninsula lies to the west of Big Ben and consists of trachyte and basanite lavas and domes. Laurens Peninsula lavas have ages in the range 5.1 ± 3.5 to 76.6 ± 5.5 ka. Young basaltic cones are located around the coast of Heard Island and range in age from 1.9 ± 3.8 to 13.3 ± 4.1 ka. Heard Island is a relatively small volcanic edifice with a low average magma discharge rate (~0.0002 km3/yr) when compared with other intraplate basaltic volcanic islands. [ABSTRACT FROM AUTHOR]

Sedimentary rocks are rarely preserved on reefless volcanic oceanic islands because their sediments are mostly exported from coastal areas towards the deep sea and such islands typically undergo subsidence. In contrast, the exceptional geological record of the uplifted Santa Maria Island (Azores) provides a unique opportunity to gain insight on such coastal systems. This study focuses on a locality at Ponta do Cedro (eastern Santa Maria Island), which features a series of marine fossiliferous sediments wedged between steep lava deltas. As demonstrated by local structure, these sediments correspond to clinoforms deposited on the steep submarine slope of an active volcanic island, implying transport from shallow waters to greater depths and subsequent colonization by benthic communities. Rapid volcanic progradation eventually sealed the deposits, allowing for their preservation and providing a rare snapshot of the ecology during those intervals, in addition to insights on sedimentary dynamics along submarine island slopes. This study reveals spatial relationships between wedges of sedimentary bodies encapsulated by lavas in the Ponta do Cedro section, and interprets depositional processes preserved in those strata based on sedimentological and palaeontological data. The dynamics of the environment are mostly related to relative sea‐level changes, intense volcanic activity and regional uplift during the Neogene. [ABSTRACT FROM AUTHOR]

Background: Due to their isolation, islands offer excellent areas for the study of distribution of benthic diatoms. On the other hand, diatoms bearing canal raphe have received less attention compared to other groups of diatoms such as Navicula, Pinnularia or Amphora. Questions: Is it possible that thermal springs on islands offer a refuge for infrequent diatom species? Studied species: Platichthys furnensis C. Delgado, V. Gonçalves & S.F.P. Almeida sp. nov. Study site and dates: The species here described was collected in the epilithon of a thermal spring in São Miguel Island (Azores Archipelago, Portugal) in September 2015. Methods: This new taxon was compared to other diatom species of the genera Nitzschia, Tryblionella, Entomoneis and Hantzschia and to the other species of the genus Platichthys. The morphology is documented by light and scanning electron images and discussed in detail. Results: Platichthys furnensis was found in a thermal pool, a similar habitat to the one where P. krammeri type was collected in Chile in 1940. P. furnensis has many structures that are characteristic of the recently described genus Platichthys, including raised canal raphe and fibulae, compressed valve face, steep valve face and numerous open copulae. Conclusions: The description of the new taxon is interesting because it is the first species within Platichthys to be described from the Northern Hemisphere.

ABSTRACT The pedological studies carried out so far in Trindade Island (TI) have obtained patchy evidences of allophane, without detailed mineralogical and micromorphological studies to confirm the occurrence of Andosols in TI. Therefore, in this study, the mineralogical, micromorphological, physical and chemical characterization of four soil profiles from Vulcão do Paredão (P1) and Morro Vermelho formations (P2, P3, and P4) were carried on the latest volcanic events in Brazil from Trindade Island (TI) with the aim of to evaluate the presence of Andosols in this oceanic island. Profiles P1 and P2 are developed on pyroclastic bombs, and show, respectively, A-Bi- C and decapitated A-C horizons, whereas P3 and P4 are developed on lapillitic and bomb pyroclasts, show A-C horizons. The soil profiles have a reddish and brownish clayey matrix, are highly friable and show a plastic consistency. Their microstructures are granular, single grain and intergrain microaggregate, in which aggregates display an undifferentiated b-fabric. The mineralogical constituents of the bulk fraction are biotite, hematite, magnetite, ilmenite, pyroxene, olivine, halloysite, goethite, anatase, and rutile. The clay fraction is marked by the presence of halloysite, ferrihydrite, and little amounts of allophane. All soils presented andic properties and can be classified as non-allophanic Andosols. In addition, micromorphological features closely resemble those reported in Andosols from other volcanic islands from elsewhere. The predominance of halloysite in the clay fraction formed by alteration of sideromelane, suggests that allophane would be an intermediate phase of this rapid transformation favored by the wet climate conditions of the highest parts of TI.

Summary: The topographical complexity of coral reefs is of primary importance for a number of hydrodynamical and ecological processes. The present study is based on a series of high‐resolution seabottom elevation measurements along the Maupiti Barrier Reef, French Polynesia. Several statistical metrics and spectral analysis are used to characterize the spatial evolution of the coral geometrical structure from the reef crest to the backreef. A consistent fractal‐like power law exists in the spectral density of bottom elevation for length scales between 0.1 and 7 m, while at larger scale, the reef structure shows a different pattern. Such a fine characterization of the reef geometrical structure provides key elements to reconstruct the reef history, to improve the representation of reef roughness in hydrodynamical models and to monitor the evolution of coral reef systems in the context of global change. © 2020 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Volcanic eruptions can have significant impacts on plant and animal communities. Thus, it is important to understand the recovery process following these eruptions, particularly on isolated islands, in order to assist with biodiversity management and conservation. We studied relationships between vegetation structure and avian species composition on Miyakejima Island, Japan, where a volcanic eruption in 2000 destroyed almost half of the vegetated land. Bird species and nine vegetation variables were surveyed at 24 sampling sites from 2011 to 2014. The results showed that avian species composition mainly varied along two vegetation variables, namely plant species richness and total basal area of all tree species. Bird species were classified into four groups, that is, grassland species, widely distributed species, developing-forest species, and developed-forest species. Developed-forest species were only recorded at the sites where vegetation height was more than 10 m. The relationship between developed-forest bird abundance and vegetation height was similar to that between total basal area of all tree species and vegetation height. The restoration of mature evergreen forest is essential to conserve avian diversity on the island, and natural seed dispersal by birds plays an important role in supporting forest restoration after a major disturbance. [ABSTRACT FROM AUTHOR]

This paper presents new bathymetric data acquired around Linosa Island, in the Pelagie Archipelago, revealing the submarine extension of the volcanic edifice, more wide and complex than previously known. The seafloor of Linosa, from the coastal area to about 1000 m depth, was mapped with multibeam systems during the ‘Linosa 2016’ and ‘BioGeoLin 2017’ surveys. A bathymetric map of the surveyed area (about 298 km2) was drawn at the original 1:30,000 scale. Overall, the submarine portions of Linosa extend on a total area of about 159 km2 and are preferentially developed in a NW-SE direction, in agreement with the regional main tectonic trend in the area. The new bathymetric data allow to recognize different sectors in the submarine extension of the volcanic edifice where constructional (volcanic) activity alternates with erosive-depositional processes affecting the submarine flanks of the island. [ABSTRACT FROM AUTHOR]

Submerged flanks of volcanic islands are prone to hazards including submarine landslides that may trigger damaging tsunamis and sediment-laden seafloor flows (called “turbidity currents”). These hazards can break seafloor infrastructure which is critical for global communications and energy transmission. Small Island Developing States are particularly vulnerable to these hazards due to their remote and isolated nature, small size, high population densities, and weak economies. Despite their vulnerability, few detailed offshore surveys exist for such islands, resulting in a geohazard “blindspot,” particularly in the South Pacific. Understanding how these hazards are triggered is important; however, pin-pointing specific triggers is challenging as most studies have been unable to link continuously between onshore and offshore environments, and focus primarily on large-scale eruptions with sudden production of massive volumes of sediment. We address these issues by integrating the first detailed (2 × 2 m) bathymetry data acquired from Tanna Island, Vanuatu with a combination of terrestrial remote sensing data, onshore and offshore sediment sampling, and documented historical events. Mount Yasur on Tanna has experienced low-magnitude Strombolian activity for at least the last 600 years. We find clear evidence for submarine landslides and turbidity currents, yet none of the identified triggers are related to major volcanic eruptions, in contrast to conclusions from several previous studies. Instead we find that cascades of non-volcanic events (including outburst floods with discharges of >1,000 m3/s, and tropical cyclones), that may be separated by decades, are more important for preconditioning and triggering of landslides and turbidity currents in oversupplied sedimentary regimes such as at Tanna. We conclude with a general model for how submarine landslides and turbidity currents are triggered at volcanic and other heavily eroding mountainous islands. Our model highlights the often-ignored importance of outburst floods, non-linear responses to land-use and climatic changes, and the complex interactions between a range of coastal and tectonic processes that may overshadow volcanic regimes.

Raised marine terraces and submerged insular shelves are used through an integrated approach as markers of relative sea level changes along the flanks of the Salina volcanic island (Aeolian Arc, southern Italy) for the purpose of evaluating its crustal vertical deformation pattern through time. Paleo sea level positions are estimated for the terrace inner margins exposed subaerially at different elevations and the erosive shelf edges recognized offshore at different depths. Compared with the eustatic sea levels at the main highstands (for the terraces) and lowstands (for the shelf edges) derived from the literature, these paleo sea level markers allowed us to reconstruct the interplay among different processes shaping the flanks of the island and, in particular, to quantify the pattern, magnitudes and rates of vertical movements affecting the different sectors of Salina since the time of their formation. A uniform uplift process at rates of 0.35 m ka−1 during the Last Interglacial is estimated for Salina (extended to most of the Aeolian Arc) as evidence of a regional (tectonic) vertical deformation affecting the sub‐volcanic basement in a subduction‐related geodynamic context. Before that, a dominant subsidence at rates of 0.39–0.56 m ka−1 is instead suggested for the time interval between 465 ka (MIS 12) and the onset of the Last Interglacial (MIS 5.5, 124 ka). By matching the insular shelf edges with the main lowstands of the sea level curve, a relative age attribution is provided for the (mostly) submerged volcanic centres on which the deepest (and oldest) insular shelves were carved, with insights on the chronological development of the older stages of Salina and the early emergence of the island. The shift from subsidence to uplift at the Last Interglacial suggests a major geodynamic change and variation of the stress regime acting on the Aeolian sub‐volcanic basement. © 2019 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Volcanic soils cover only approximately 1% of the Earth's surface, yet they support 10% of the world's population due to their inherent fertility. However, deep magmatic processes may lead to depletion of certain elements in volcanic rocks. The imbalance of essential elements, such as cobalt, in soil parent materials can affect the health of plants and grazing animals and, thus, humans. Within the particular geological context of the Azores, the present study aims to assess cobalt concentration in volcanic soils to predict the risk of cobalt deficiency in animals and humans. Samples from agricultural topsoils and pasture grass were collected in six volcanic regions of São Miguel Island, and their physicochemical properties were measured, including selected transition metal element contents, such as iron, manganese and cobalt. The soil cobalt concentration was below 5 mg/kg in Povoação< Furnas/Congro< Sete Cidades< Fogo and was higher than 10 mg/kg in Picos< Nordeste. Cobalt concentrations were very low in pasture grass. Values below 0.1 mg/kg were observed in Furnas/Congro

The current understanding of tsunamis generated by volcanic-island landslides is reliant on numerical models benchmarked against reconstructions of past events. As the largest historical event with timed tsunami observations, the 1888 sector collapse of Ritter Island, Papua New Guinea provides an outstanding opportunity to better understand the linked process of landslide emplacement and tsunami generation. Here, we use a combination of geophysical imaging, bathymetric mapping, seafloor observations and sampling to demonstrate that the Ritter landslide deposits are spatially and stratigraphically heterogeneous, reflecting a complex evolution of mass-flow processes. The primary landslide mass was dominated by well-bedded scoriaceous deposits, which rapidly disintegrated to form an erosive volcaniclastic flow that incised the substrate over much of its pathway. The major proportion of this initial flow is inferred to have been deposited up to 80 km from Ritter. The initial flow was followed by secondary failure of seafloor sediment, over 40 km from Ritter. The most distal part of the 1888 deposit has parallel internal boundaries, suggesting that multiple discrete units were deposited by a series of mass-flow processes initiated by the primary collapse. The last of these flows was derived from a submarine eruption triggered by the collapse. This syn-collapse eruption deposit is compositionally distinct from pre- and post-collapse eruptive products, suggesting that the collapse immediately destabilised the underlying magma reservoir. Subsequent eruptions have been fed by a modified plumbing system, constructing a submarine volcanic cone within the collapse scar through at least six post-collapse eruptions. Our results show that the initial tsunami-generating landslide at Ritter generated a stratigraphically complex set of deposits with a total volume that is several times larger than the initial failure. Given the potential for such complexity, there is no simple relationship between the volume of the tsunamigenic phase of a volcanic-island landslide and the final deposit volume, and deposit area or run-out cannot be used to infer primary landslide magnitude. The tsunamigenic potential of prehistoric sector-collapse deposits cannot, therefore, be assessed simply from surface mapping, but requires internal geophysical imaging and direct sampling to reconstruct the event. • Ritter Island's sector collapse provides an exemplar of volcanic tsunami hazards. • Deposit heterogeneity reflects erosion, secondary failure and a triggered eruption. • The volume of the distal deposit alone far exceeds the tsunamigenic failure. • A single catastrophic collapse led to stratigraphically complex distal deposits. • Accurate assessment of tsunami potential requires internal imaging and sampling. [ABSTRACT FROM AUTHOR]

Tracking early oceans on Mars has fundamental climatic and exobiological implications but requires unambiguous datable markers. Here we show that the Olympus Mons giant volcano shares morphological similarities with active volcanic islands on Earth where major constructional slope breaks systematically occur at the sea-air transition in response to sharp lava viscosity contrasts. We propose that the upper rim of the 6-km high concentric main escarpment surrounding Olympus Mons most likely formed by lava flowing into liquid water when the edifice was an active volcanic island during the late Noachian - early Hesperian. Similar features on the northern flank of the 1800 km-distant Alba Mons volcano further support an extended early Ocean initially occupying Martian lowlands. Abnormal current shoreline heights imply major surface uplift promoted by internal dynamics during the main phase of development of the Tharsis Bulge at some time during the Hesperian. After ocean retreat, the uplifted shorelines were partly blanketed by late sub-aerial activity during the Amazonian. The newly proposed volcanic shorelines can be dated by radiometric methods, constituting exceptional targets to track early liquid water at key temporal steps and provide valuable insights into the timing and fate of Martian Oceans. • Olympus Mons (OM) shares morphological similarities with volcanic islands on Earth. • Upper rim of OM main basal escarpment support lava flowing into early liquid water. • Similar characteristics on Alba Mons support extended early ocean in Martian lowlands. • Excessive shoreline height is modelled by major uplift during upward plume load. • Radiometric dating of such volcanic shorelines can help tracking early Martian oceans. [ABSTRACT FROM AUTHOR]

Study region: Montserrat, Lesser Antilles, Caribbean. Study focus: Analysis of δ2H and δ18O isotopes, and chlorofluorocarbon (CFC) anthropogenic tracers in Montserrat groundwater provides insights into the age and provenance of the spring waters. New hydrological insights: δ2H and δ18O analysis indicates uniform recharge elevations for groundwaters on Montserrat. CFC-11 and CFC-12 analysis reveals age differences between isotopically similar, high elevation springs and low elevation aquifer waters. Low CFC concentrations within a confined low elevation aquifer suggest water ages of ∼45 years. High CFC concentrations in the northern and western springs are explained by rapid infiltration of cool (high CFC concentration) rainfall into saturated compartments, with flow through the vadose zone to the phreatic zone dominated by compartment flow. Lower CFC concentrations in a number of aligned warmer springs suggest a contribution from older, warmer waters from depth. Temperatures and CFC concentrations indicate older component supply rates of up to 8 L/s to the highest yielding spring on Centre Hills, with contributions of up to 75% in the warmest spring waters.