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The existence of worldwide tsunamis driven by atmospheric waves--or planetary meteotsunami waves--was first hypothesized after the catastrophic eruption of the Krakatau volcano in 1883. The then sparse and low-quality tide [...]

The eastern lobe of the Alaskan White River Ash volcanic event of AD 846-848 blanketed portions of Yukon and Northwest Territories, Canada, in 5 to 50 cm of tephra. The eruption has been linked to concurrent changes among hunter-gatherers, including the spread of new technologies and the continent-wide migration of a group of Dene ancestors from Subarctic Canada to the United States. We use published palaeoenvironmental data (primarily pollen and charcoal profiles) as well as studies of modern ash fall ecology and human health hazards associated with eruptions to reconstruct effects of the White River Ash east event on northern hunter-gatherer subsistence. While many components of local ecosystems appear to have rebounded quickly from ash deposition, we deduce a more pronounced impact on the important game species of caribou and salmon, the seasonal migration paths of which were intersected by thick deposits of ash. A trophic model informed by palaeoenvironmental data and ethnohistoric records suggests that negative biological effects of the ash temporarily pushed hunter-gatherer populations to neighbouring and less affected kin groups for up to 100 years. This synthesis contextualises archaeological theories of human responses to ecological disturbance events in circumpolar landscapes. Key words: Subarctic; hunter-gatherer; volcano; tephra; White River Ash; ethnohistory; pollen; ecology; disaster; palaeoenvironment; archaeology Le lobe occidental du depot de cendres volcaniques White River Ash, en Alaska, remontant aux annees 846-848 A.D., a recouvert certaines parties du Yukon et des Territoires du Nord-Ouest, au Canada, d'une couche de tephra de 5 a 50 cm. Cette eruption a ete liee a des changements simultanes chez les chasseurs-cueilleurs, dont l'adoption de nouvelles technologies et la migration a l'echelle du continent d'un groupe d'ancetres denes, de la zone subarctique canadienne jusqu'aux Etats-Unis. Nous avons publie des donnees paleoenvironnementales (principalement des profils de pollen et de charbon de bois) ainsi que des etudes d'ecologie moderne de chutes de cendres et de dangers pour la sante des etres humains decoulant d'eruptions afin de reconstituer les effets du depot occidental White River Ash sur la subsistance des chasseurs-cueilleurs nordiques. Meme si de nombreuses composantes des ecosystemes locaux semblent s'etre remises rapidement des depots de cendres, nous deduisons que les repercussions ont ete plus prononcees sur les especes de gibier de caribou et sur le saumon, dont les voies de migration saisonniere croisaient les epais depots de cendres. Un modele trophique etabli a l'aide de donnees paleoenvironnementales et d'enregistrements ethnohistoriques suggere que les effets biologiques negatifs des cendres ont pousse temporairement les populations de chasseurs-cueilleurs chez des groupes apparentes avoisinants et moins touches pendant une centaine d'annees. Cette synthese met en contexte les theories archeologiques se rapportant aux reactions humaines vis-a-vis d'evenements de perturbation ecologique dans les paysages circumpolaires. Mots cles : subarctique; chasseur-cueilleur; volcan; tephra; White River Ash; ethnohistoire; pollen; ecologie; catastrophe; paleoenvironnement; archeologie Traduit pour la revue Arctic par Nicole Giguere., INTRODUCTION Large-scale natural disturbances in the past have garnered archaeological interest as catalysts of change. Volcanic eruptions, earthquakes, and tsunamis have been portrayed as stimuli of new modes of cultural [...]

Aerosols have a potentially large effect on climate, particularly through their interactions with clouds, but the magnitude of this effect is highly uncertain. Large volcanic eruptions produce sulfur dioxide, which in turn produces aerosols; these eruptions thus represent a natural experiment through which to quantify aerosolcloud interactions. Here we show that the massive 20142015 fissure eruption in Holuhraun, Iceland, reduced the size of liquid cloud dropletsconsistent with expectationsbut had no discernible effect on other cloud properties. The reduction in droplet size led to cloud brightening and global-mean radiative forcing of around 0.2 watts per square metre for September to October 2014. Changes in cloud amount or cloud liquid water path, however, were undetectable, indicating that these indirect effects, and cloud systems in general, are well buffered against aerosol changes. This result will reduce uncertainties in future climate projections, because we are now able to reject results from climate models with an excessive liquid-water-path response., Author(s): Florent F. Malavelle (corresponding author) [1]; Jim M. Haywood [1, 2]; Andy Jones [2]; Andrew Gettelman [3]; Lieven Clarisse [4]; Sophie Bauduin [4]; Richard P. Allan [5, 6]; Inger [...]

The Hakon Mosby Mud Volcano is a highly active methane seep hosting different chemosynthetic communities such as thiotrophic bacterial mats and siboglinid tubeworm assemblages. This study focuses on in situ measurements of methane fluxes to and from these different habitats, in comparison to benthic methane and oxygen consumption rates. By quantifying in situ oxygen, methane, and sulfide fluxes in different habitats, a spatial budget covering areas of 10-1000-m diameter was established. The range of dissolved methane efflux (770-2 mmol [m.sup.-2] [d.sup.-1]) from the center to the outer rim was associated with a decrease in temperature gradients from 46[degrees]C [m.sup.-1] to < 1[degrees]C [m.sup.-1], indicating that spatial variations in fluid flow control the distribution of benthic habitats and activities. Accordingly, total oxygen uptake (TOU) varied between the different habitats by one order of magnitude from 15 mmol [m.sup.-2] [d.sup.-1] to 161 mmol [m.sup.-2] [d.sup.-1]. High fluid flow rates appeared to suppress benthic activities by limiting the availability of electron acceptors. Accordingly, the highest TOU was associated with the lowest fluid flow and methane efflux. This was most likely due to the aerobic oxidation of methane, which may be more relevant as a sink for methane as previously considered in submarine ecosystems. doi: 10.4319/lo.2010.55.6.2366

During the 2002 eruption, the NW flank of Stromboli volcano (Southern Italy) experienced large landslides that produced tsunami waves with a maximum runup of 10 m in height. This paper focuses on the geomechanical behavior of the loose volcaniclastic layers, the weakest component of the deposit forming the volcano flank. Tests on the coarse-grained volcaniclastic soil and on the rock material forming the grains were conducted in dry conditions, a feature of the subaerial slope. The rock material, in spite of its high porosity, exhibits relatively high stiffness and strength due to the remarkable continuity of the solid skeleton. Accordingly, the volcaniclastic soil is characterized by high shear strength. During shear tests, however, significant grain crushing occurs, which partly explains the nonlinear shear strength envelope and the strain softening associated with contractive behavior. Grain crushing was also found to affect compressibility and its time dependency, investigated under oedometric conditions. DOI: 10.1061/(ASCE)GT.1943-5606.0000218 CE Database subject headings: Rocks; Shear strength; Laboratory tests; Landslides; Volcanic ash; Italy. Author keywords: Volcanic rocks; Shear strength; Laboratory test; Landslides; Volcaniclastic soil.

Destruction of human property by lava flow invasion is a significant volcanic hazard at Mount Etna (Italy), where reliable risk maps are important for risk mitigatinn. We present new high-resolution quantitative risk maps of Mount Etna that are based on lava flow simulations starting from more than 70,000 different potential vents, a probability distribution of vent location, an empirical relationship for the maximum length of lava flows, and a database of buildings. In addition to standard risk maps, which classify areas according to the expected damage at each point, we classify each point of the volcano with respect to the damage that would occur if a vent opened at that point. The resulting maps should help local authorities in making the necessary decisions to deal with ongoing eruptions and to plan long-term land use. doi: 10.1130/G30187A.1

Tazieffite, ideally [Pb.sub.20][Cd.sub.2][(As,Bi).sub.22][S.sub.50][Cl.sub.10], is a new mineral from the high-temperature fumaroles of the Mutnovsky volcano, Kamchatka Peninsula, Russian Federation. It occurs as tiny, slender, needleshaped crystals, up to 400 [micro]m long and 10 [micro]m across, generally forming fibrous aggregates. Tazieffite is closely associated with greenockite, galena, mutnovskite, kudriavite, and Cd-rich cannizzarite. Other minerals spatially associated are pyrite, anhydrite, and cristobalite. Tazieffite is silvery-gray in color, occasionally with a magenta tint when it forms aggregates of extremely fine needles. It has a black streak and metallic luster. In plane-polarized incident light, tazieffite is weakly bireflectant and weakly pleochroic from dark gray to a blue-gray. Between crossed polars, the mineral is weakly anisotropic, without characteristic rotation tints. Reflectance percentages measured in air ([R.sub.min] and [R.sub.max]) for a single grain are 33.9, 34.1 (471.1 nm), 32.8, 33.0 (548.3 nm), 32.4, 32.6 (586.6 nm), and 30.9, 31.1 (652.3 nm), respectively. Electron microprobe analyses yield the following ranges of concentrations: Pb 41.88-44.14 (avg. 42.90), Cd 0.87-1.16 (avg. 1.03), Sn 0.31-0.69 (avg. 0.48), Bi 20.43-22.94 (avg. 21.90), As 8.64-10.73 (avg. 9.66), S 16.10-17.48 (avg. 16.58), Se 0.82-1.28 (avg. 1.04), C12.39-2.77 (avg. 2.63), Br 0.09-0.15 (avg. 0.12), 1 0.27-0.58 (avg. 0.42). The empirical chemical formula, calculated on the basis of 44 cations, is [Pb.sub.20.06][([Cd.sub.0.89] [Sn.sub.0..39]In002).sub.[sigma]1. 30][([As.sub.12.9] [Bi.sub.10,15]).sub.[sigma]22.64] [([S.sub.50.08][Se.sub.1.28]).sub.[sigma].sub.51.36][([Cl.sub.7.18] [I.sub.0.32][Br.sub.0.15]).sub.[sigma]7.65]. Tazieffite is closely related to the halogen-sulfosalt vurroite, [Pb.sub.20] [Sn.sub.2][Bi.sub.22][S.sub.54][Cl.sub.6], both from a chemical and structural point of view. It represents the (Cd,As)-dominant of vurroite, according to the coupled heterovalent substitution [Sn.sup.4+] + 2[S.sup.2] [right arrow] [Cd.sup.2+] + 2[Cl.sup.-]. The crystal structure of tazieffite was refined in the space group C2/c to R = 0.0370 for 4271 reflections with I > 2[sigma](I). Unit-cell parameters are a = 8.3520(17), b = 45.5920(92), c = 27.2610(55) [Angstrom], [beta] = 98.84(3), with V = 10257(4) [[Angstrom].sup.3], and Z = 4. The structure of tazieffite consists of lozenge-shaped composite rods made of coordination polyhedra of Pb around an octahedrally coordinated (Cd,Sn,Pb) position, interconnected into layers parallel to (010). These layers are separated by ribbons of As and Bi in distorted octahedral coordination. The ribbons form wavy, discontinuous double layers of the PbS archetype. Lone electron pairs of As and Bi are accommodated in the central portions of the PbS-like layers. The possibility that small amounts of N[H.sup.+.sub.4] are incorporated in the crystal structure of tazieffite is discussed. The name of this new mineral species (IMA 2008-012) honors Haroun Tazieff (Warszawa, May 11, 1914-Paris, February 6, 1998), famous Belgian/French volcanologist, who was a pioneer in the field study of volcanoes and devoted his life to the study of volcanic gases. Keywords: Tazieffite, chloro-sulfosalt, Mutnovsky volcano, fumaroles, vurroite isotype

Kilauea may be one of the world's most intensively monitored volcanoes, but its eruptive history over the past several thousand years remains rather poorly known. Our study has revealed the vestiges of thin basaltic tephra deposits, overlooked by previous workers, that originally blanketed wide, near-summit areas and extended more than 17 km to the south coast of Hawai'i. These deposits, correlative with parts of tephra units at the summit and at sites farther north and northwest, show that Kilauea, commonly regarded as a gentle volcano, was the site of energetic pyroclastic eruptions and indicate the volcano is significantly more hazardous than previously realized. Seventeen new calibrated accelerator mass spectrometry (AMS) radiocarbon ages suggest these deposits, here named the Kulanaokuaiki Tephra, were emplaced ca. A.D. 400-1000, a time of no previously known pyroclastic activity at the volcano. Tephra correlations are based chiefly on a marker unit that contains unusually high values of Ti[O.sub.2] and [K.sub.2]O and on paleomagnetic signatures of associated lava flows, which show that the Kulanaokuaiki deposits are the time-stratigraphic equivalent of the upper part of a newly exhumed section of the Uwekahuna Ash in the volcano's northwest caldera wall. This section, thought to have been permanently buried by rockfalls in 1983, is thicker and more complete than the previously accepted type Uwekahuna at the base of the caldera wall. Collectively, these findings justify the elevation of the Uwekahuna Ash to formation status; the newly recognized Kulanaokuaiki Tephra to the south, the chief focus of this study, is defined as a member of the Uwekahuna Ash. The Kulanaokuaiki Tephra is the product of energetic pyroclastic falls; no surge- or pyroclastic-flow deposits were identified with certainty, despite recent interpretations that Uwekahuna surges extended 10-20 km from Kilauea's summit. Keywords: Kilauea volcano, pyroclastic eruptions, high Ti[O.sub.2] and [K.sub.2]O marker unit, pyroclastic surges, stratigraphy, radiocarbon ages, paleomagnetism.

The spaceborne thermal monitoring of the great eruption of Pu'u 'O'o-Kupaianaha in Hawaii (1987 to present) was attempted, integrating high-resolution SWIR-TIR and low-resolution MIR-TIR observations. Data acquired by multispectral payloads ASTER and MODIS onboard spacecraft Terra, and MODIS onboard Aqua, were processed behind real time by the use of computing routines 'MyVOL' and 'MyMOD' based on assessed theory and designed for real-time operations. The process was tested against the 2000-2005 eruptive history, both in geometry and volume dynamics of the lava flow. Here, instant lava effusion rates obtained from approximately 1800 cloud-free (over a total > 3000) day-/nighttime MODIS scenes and 12 cloud-free (over a total of 30) nighttime ASTER scenes are compared with each other and with volcanological ground truth composed of gas (S[O.sub.2])- and electromagnetic potential (very low frequency)-derived eruption rates. Remote-sensed eruption rates are consistent with ground truth from approximately 1 [m.sup.3]/s up to the peak effusion rates of 1.2-1.3 million [m.sup.3]/day observed in 2005. Index Terms--Aqua, ASTER, eruption rate, Hawaii, lava, MODIS, Terra, volcano.

Alteration textures in volcanic glass from the seafloor fall into two classes, one suggestive of abiotic/diffusive hydration and chemical exchange, and another likely to be caused by microbial, cavity-forming, congruent dissolution. Glass bioalteration is common in submarine lavas throughout the world's ocean, dominant in the upper 300 m of the oceanic crust, and found in all well-preserved ophiolites and greenstone belts dating back to 3.5 Ga. It may yield a significant fraction of the global biomass and geochemical fluxes and is relevant to the development of the earliest life on Earth. We present a critical review concerning these glass bioalteration textures and present new data on their microchemical environment. We explore arguments for their biogenicity and further develop the prevalent model for their formation by relating corrosion morphology to the mechanism of microbial dissolution, Biological alteration produces conspicuous micron-scale granular and tubular textures. Granular glass alteration is well explained by colonizing microbes that selectively dissolve the glass in their contact area, forming a sponge-like interconnected network of micron-sized cavities along glass surfaces. Tubular alteration meanwhile, is more likely to be caused by filamentous cell extensions in a process similar to fungal tunneling of soil feldspars and marine carbonates. While we see clear functional similarities to fungal dissolution behavior, we do not know whether fungal or prokaryotic organisms are involved. However, this functional constraint may eventually help to identify potential microbes responsible for these features, potentially including eukaryotic or prokaryotic organisms. Yet, we caution that these organisms may be difficult to identify and to study, because they are likely to be sparsely distributed, slow growing, and difficult to cultivate. Keywords: volcanic glass microbes bioerosion oceanic crust ophiolites greenstone belts

The author talks about the extremely large John Day Fossil Beds that are found to be buried under two towering mountain ranges of East Oregon, namely the Coast Range and the Cascades. These fossil beds are shown to be well protected beneath the John Day National Monument and are shown to be formed by the volcanic eruptions and tuffs.

The northern Antarctic Peninsula region has undergone ~10 m.y. of eruptive activity by basaltic volcanoes, mainly in subglacial settings. Spectacular exposures of lava-fed deltas, capped by basalt flows and commonly underlain by glacigenic sediments on top of a Cretaceous sedimentary 'basement,' characterize James Ross, Vega, and other islands and promontories in the region. Neogene strata are collectively known as the James Ross Island Volcanic Group and record a cryptic history of glaciation, with the timing of events determinable by argon-isotope dating. Focusing especially on the glacigenic sediments themselves, and their relationships with overlying or bounding volcanic rocks, we define facies associations related to (1) eruptions beneath thick ice (>200 m) that produced lava-fed deltas resting on, and intermingling with, diamictite; and (2) eruptions under marine conditions that typically culminated in the development of several tuff-cone successions, some on top of presumably relict glacially striated surfaces. A combination of provenance studies on clasts in the glacigenic sediments, some of which are derived from the Antarctic Peninsula, and geochronology, leads to the conclusion that an Antarctic Peninsula Ice Sheet extended over James Ross and Vega Islands at about the time that the main volcanic edifices began to grow, i.e., prior to ca. 6.2 Ma at least. Much of the subsequent development of the succession is attributed to the interaction between the growing volcanoes and local ice caps. Full resolution of glacial-interglacial events in this region promises to inform the debate about the stability of the most climatically sensitive part of the Antarctic Ice Sheet during the Neogene Period. Keywords: Neogene glacial fluctuations, James Ross Island, Antarctic Peninsula Ice Sheet, glacier-volcano interaction, glacigenic sediments, lava-fed deltas, argon dating, strontium dating.

Scoria-cone eruptions are typically low in volume and explosivity compared with eruptions from stratovolcanoes, but they can affect local populations profoundly. Scoriacone eruption effects vary dramatically due to eruption style, tephra blanket extent, climate, types of land use, the culture and complexity of the affected group, and resulting governmental action. A comparison of a historic eruption (Paricutin, Mexico) with prehistoric eruptions (herein we primarily focus on Sunset Crater in northern Arizona, USA) elucidates the controls on and effects of these variables. Long-term effects of lava flows extend little beyond the flow edges. These flows, however, can be used for defensive purposes, providing refuges from invasion for those who know them well. In arid lands, tephra blankets serve as mulches, decreasing runoff and evaporation, increasing infiltration, and regulating soil temperature. Management and retention of these scoria mulches, which can open new areas for agriculture, become a priority for farming communities. In humid areas, though, the tephra blanket may impede plant growth and increase erosion. Cultural responses to eruptions vary, from cultural collapse, through fragmentation of society, dramatic changes, and development of new technologies, to little apparent change. Eruptions may also be viewed as retribution for poor behavior, and attempts are made to mollify angry gods. Keywords: Scoria cones, geoarchaeology, volcanic risk, agriculture, Sunset Crater, Paricutin.

Millions of people live in the shadows of volcanoes and massive eruptions though rare can be deadly. A study examining the various parts of eruptions that are most hazardous to humans is illustrated.

The volcanic hazard potential of Mount Etna volcano is currently nourished by longlasting, powerful eruptions of basaltic magmas coupled with increased seismicity and ground deformation, and the world's largest discharge of volcanic gases. The current evolutionary cycle of Mount Etna activity is consistent with subduction-related chemical modifications of the mantle source. Arrival of a new mantle-derived magma batch beneath the volcano has been hypothesized, but is still elusive among the erupted products. Here we demonstrate petrological and geochemical affinities between the magmas supplying modern eruptions and high-Mg, fallstratified (FS) basalts ejected violently ~4 k.y. ago. The FS primitive magmas (~13 wt% MgO) are characteristically volatile enriched (at least 3.8 wt% [H.sub.2]O and 3300 ppm C[O.sub.2]), and bear a trace element signature of a garuet-bearing, metasomatized source (high Gd/Yb, K/La, U/Nb, Pb/Ce, Ca/Al). They started crystallizing olivine ([Fo.sub.91]), clinopyroxene (Mg# 92.5), and Cr spinel deep in the plumbing system (>5 kbar), contributing to the cumulate piles at depth and to differentiated alkaline basalt and trachybasalt magmas in the shallow conduit. Continuous influx of mantle-derived, volatile-rich magmas, such as those that supplied the FS fallout, provides a good explanation for major compositional and eruptive features of Mount Etna. Keywords: Mount Etna, volcano, picrite, melt inclusions, volatiles, degassing, mantle, metasomatism.

A common association of thin, late Holocene Mono and Inyo crater tephra beds buried by debris flows within a 250-km-long corridor of western Nevada suggests that there has been at times a genetic link between these two otherwise independent processes. The unambiguous depositional relations and the undisturbed character of the tephra beds at more than 20 sites indicate that tephra deposition was often followed by burial under debris flows produced by intense precipitation. Considering that average return periods are hundreds of years for such storms, it is highly improbable that this stratigraphic association is random coincidence. We propose that the most plausible explanation for this association is that some Plinian ash columns produced intense thunderstorms, resulting in large debris flows that buried the tephra beds. Keywords: Plinian eruptions, Mono and Inyo Craters, tephra, debris flows.

Five Pleistocene basaltic volcanoes in Crater Flat (southern Nevada) demonstrate the complexity of eruption processes associated with small-volume basalts, and the effects of initial emplacement characteristics on posteruptive geomorphic evolution of the volcanic surfaces. The volcanoes record explosive processes ranging from 'classical' Strombolian mechanisms to, potentially, violent Strombolian mechanisms. Cone growth was accompanied and sometimes disrupted by effusion of lavas from the bases of cones. Pyroclastic cones were built upon a gently southward-sloping surface and were prone to failure of their downslope (southern) flanks. Early lavas flowed primarily southward and, at Red and Black Cone volcanoes, carried abundant rafts of cone material on the tops of the flows. These resulting early lava fields eventually built platforms such that later flows erupted from the eastern (at Red Cone) and northern (at Black Cone) bases of the cones. Three major surface features--scoria cones, lava fields with abundant rafts of pyroclastic material, and lava fields with little or no pyroclastic material--experienced different posteruptive surficial processes. Failure to account for the different initial surface features can lead to erroneous conclusions about the relative ages of the surfaces based upon modern morphology. Conversely, the recognition of different volcanic surfaces provides the opportunity to study the effects of different initial properties upon posteruptive geomorphic processes. Contrary to previous interpretations that the individual volcanoes were emplaced by polycyclic eruptions (separated by thousands or tens of thousands of years), we argue that the Pleistocene Crater Flat volcanoes are monogenetic, each having formed in a single eruptive episode lasting up to a few years. We show that all eruptive products emanated from the areas of the volcanoes' main cones rather than from scattered vents, as inferred by previous workers. These conclusions provide insight into the processes associated with continental basaltic magmatism and information related to the geometry and timing of volcanic events, which is useful in risk assessments. Keywords: scoria cone, basalt, lava flow, polycyclic, monogenetic, Strombolian, violent Strombolian.

Evaluating volcanic hazards requires knowledge of the processes that trigger eruptions and the nature and timing of geophysical signals related to these processes. One approach to addressing this need is to link geophysically observable signals (e.g., those related to seismic, aeromagnetic, inflationary, or degassing processes) to pre-eruptive magmatic events deduced (in hindsight) from studies of erupted magmas. Here we present data on sanidine crystals from the A.D. 79 eruption of Vesuvius that show abrupt changes in Ba concentration caused by magma chamber recharge events prior to eruption. These changes have been degraded by diffusion during the time interval between recharge and eruption, and we have determined the length of this time interval by modeling the measured Ba concentration gradients. The results identify three distinct recharge events in the century before the eruption, the most recent occurring ~20 yr beforehand. Keywords: magma, Vesuvius, recharge, diffusion, strontium isotopes.