Series Of Eruptions Research Articles

Francis Alive and Aloft: Franciscan Apocalypticism in the Colonial Andes

The seventeenth century opened with a bang, literally. In the year 1600, on the first Friday in the season of Lent, sometime between noon and 3:00 PM (that is, at the hour of the accustomed Lenten penitential processions), the Peruvian volcano of Huaynapudna began a protracted series of explosions and eruptions. It was the largest recorded volcanic eruption in the Western Hemisphere, greater by far than that of Mount Vesuvius in 79 CE, or Mount St. Helens in 1980, and only slightly smaller than the colossal eruption of Krakatoa, Indonesia, in 1883. The event sent both Christian Spaniards and neo-Christian Indians searching for answers to apocalyptic questions. On that same Friday, February 18, 1600, several other violent earthquakes leveled buildings nearby.

Crustal-scale recycling in caldera complexes and rift zones along the Yellowstone hotspot track: O and Hf isotopic evidence in diverse zircons from voluminous rhyolites of the Picabo volcanic field, Idaho

Rhyolites of the Picabo volcanic field (10.4–6.6 Ma) in eastern Idaho are preserved as thick ignimbrites and lavas along the margins of the Snake River Plain (SRP), and within a deep (>3 km) borehole near the central axis of the Yellowstone hotspot track. In this study we present new O and Hf isotope data and U–Pb geochronology for individual zircons, O isotope data for major phenocrysts (quartz, plagioclase, and pyroxene), whole rock Sr and Nd isotope ratios, and whole rock geochemistry for a suite of Picabo rhyolites. We synthesize our new datasets with published Ar–Ar geochronology to establish the eruptive framework of the Picabo volcanic field, and interpret its petrogenetic history in the context of other well-studied caldera complexes in the SRP. Caldera complex evolution at Picabo began with eruption of the 10.44±0.27 Ma (U–Pb) Tuff of Arbon Valley (TAV), a chemically zoned and normal-δ18O (δ18O magma=7.9‰) unit with high, zoned 87Sr/86Sri (0.71488–0.72520), and low-εNd(0) (−18) and εHf(0) (−28). The TAV and an associated post caldera lava flow possess the lowest εNd(0) (−23), indicating ∼40–60% derivation from the Archean upper crust. Normal-δ18O rhyolites were followed by a series of lower-δ18O eruptions with more typical (lower crustal) Sr–Nd–Hf isotope ratios and whole rock chemistry. The voluminous 8.25±0.26 Ma West Pocatello rhyolite has the lowest δ18O value (δ18Omelt=3.3‰), and we correlate it to a 1,000 m thick intracaldera tuff present in the INEL-1 borehole (with published zircon ages 8.04–8.35 Ma, and similarly low-δ18O zircon values). The significant (4–5‰) decrease in magmatic-δ18O values in Picabo rhyolites is accompanied by an increase in zircon δ18O heterogeneity from ∼1‰ variation in the TAV to >5‰ variation in the late-stage low-δ18O rhyolites, a trend similar to what is characteristic of Heise and Yellowstone, and which indicates remelting of variably hydrothermally altered tuffs followed by rapid batch assembly prior to eruption. However, due to the greater abundance of low-δ18O rhyolites at Picabo, the eruptive framework may reflect an intertwined history of caldera collapse and coeval Basin and Range rifting and hydrothermal alteration. We speculate that the source rocks with pre-existing low-δ18O alteration may be related to: (1) deeply buried and unexposed older deposits of Picabo-age or Twin Falls-age low-δ18O volcanics; and/or (2) regionally-abundant late Eocene Challis volcanics, which were hydrothermally altered near the surface prior to or during peak Picabo magmatism. Basin and Range extension, specifically the formation of metamorphic core complexes exposed in the region, could have facilitated the generation of low-δ18O magmas by exhuming heated rocks and creating the large water-rock ratios necessary for shallow hydrothermal alteration of tectonically (rift zones) and volcanically (calderas) buried volcanic rocks. These interpretations highlight the major processes by which supereruptive volumes of magma are generated in the SRP, mechanisms applicable to producing rhyolites worldwide that are facilitated by plume driven volcanism and extensional tectonics.

Origin and Evolution of the Moon

AbstractSince the Moon is the only natural satellite of the Earth, the research on the formation of the Moon can not only find out the formation mechanism of the satellites of Solar System planets but also reveal the evolution law of galaxies in the universe. Hence many hypotheses have been proposed for the Moon's formation, including fission,capture,condensation,and impact event hypothesis, but they all have problems. Recently, the author of this abstract discovered the formation mechanism of the Moon, which can be called “evolution theory”, and described as follows: During some violent volcanic eruptions of the Earth, some rock debris such as pumice through deep rock hole could achieve a velocity no less than the first cosmic velocity (7.9 km/s) to enter an orbit around the Earth, one of the biggest debris is the young Moon.The orbit of the young Moon might be much closer to the Earth than it is today. There were a lot of ejecta from the Earth in the space. Hence, the Moon has merged these ejecta to become larger and larger, and farther and farther away from the Earth.This can be proved as follows: When the Moon moved around the Earth normally, the centrifugal force produced by the Moon's rotation around the Earth and the Earth's gravitation pull on the Moon had the same size. Let M be the mass of the Earth, m1 be the mass of the Moon, rm be the radius of the Moon, r be the centroid distance between the Earth and the Moon, v be the tangential velocity of the Moon around the Earth, then Gm1M/r2=m1v2/r, therefore $v=\sqrt{GM/r}$. Near the orbit of the Moon, there were also many smaller prograde planetesimals moving around the Earth in circular orbits of radius rx(r–rm<rx<r) with velocity vx. Since $v_x=\sqrt{GM/r_x}>\sqrt{GM/r}$, which implies vx > v, these planetesimals would finally catch and merge with the Moon.Especially,if a planetesimals was large enough, it would impact the Moon forcefully, making the Moon's velocity increase to a larger value v2. Then m1v22/r>m1v2/r=Gm1M/r2, therefore the Moon moved a reasonable distance away from the Earth.The early orbit of the Moon was much closer to the Earth's atmosphere than it is now, so the Moon had absorbed much water vapor from the atmosphere to form lunar maria. Due to the constant erosion of water,a series of volcanic eruptions occurred at the bottom of lunar maria.Violent eruption could also change the orbit of the Moon around the Earth. Since most maria are on the near-side visible from Earth, so many violent volcanic eruptions at the bottom of these lunar maria could push the moon away from the Earth. This can be proved as follows: Let M be the mass of the Earth, m1 be the mass of the Moon left by the volcanic eruption, m2 be the total mass of erupted matter, m0(=m1+m2) be the total mass of the Moon before the eruption, v be the tangential velocity of the Moon around the Earth, r0 and r1 be the centroid distance between the Earth and the Moon before or after the eruption respectively; since the volcano ejected many substances toward the Earth, r1 > r0. Before the eruption, the centrifugal force produced by the Moon's rotation around the Earth and the Earth's gravitation pull on the Moon had the same size, therefore Gm0M/r02=m0v2/r0, which implies GM/r02=v2/r0. After the eruption,if the Moon hadn't changed its orbit then its velocity around the Earth was still v, so Gm1M/r12=(Gm1M/r02) (r02/r12)=(m1v2/r0) (r02/r12) =(m1v2/r1) (r0/r1)<(m1v2/r1), adding the continuous giant reaction force produced by volcanic eruption, the join force could push the Moon away from the Earth, even to an orbit where the water vapor evaporated from the Moon would be attracted back to the Earth,leaving dry lunar maria.

Thermophilic bacteria of the genus Geobacillus from permafrost volcanic sedimentary rocks

Geothermal environments on Earth are uniquehabitats for thermophilic and hyperthermophilicmicroorganisms and occur in volcanically activeregions. On the Antarctic continent and the adjacentislands, continuous volcanic activity occurredthroughout the Cenozoic era. At present, volcanoesErebus, Rittmann, and Melbourne show activity onthe continent. The islands of the South Sandwicharchipelago and Deception Island, which are adjacentto Antarctica are also of volcanic origin and arelocated in the zone of tectonic activity.The conditions in the thermal ecosystems localizednear a volcanic crater or an outlet of a fumarolesharply contrast with the environmental conditions onthe continent, which are characterized by negativeaverage annual temperatures, strong winds, and a highlevel of UV radiation in the summer period.Such ecosystems, which are geothermal oases isolated from one another, have been studied in detail,including those on the Antarctic continent [1–6].However, it is still unclear what occurs to microorganisms in the case of cessation of the geothermal activityand transfer of the ecosystems to the permafrost state.It may be suggested that if microorganisms from thegeothermal niches of Antarctic volcanoes encountercold conditions where the maximal temperature doesnot rise above 0°C, natural cryoconservation of themicrobial community in permafrost volcanic ashes orcinder occurs.The goal of the present work was to study the possibility of preservation of viable thermophilic microorganisms in permafrost volcanic rocks.In the work, the permafrost volcanic rocks of theDeception Island situated in the Bransfield Strait nearthe northwestern coast of the Antarctic Peninsula werestudied. The last series of volcanic eruptions wasrecorded in 1967–1970; however, the geothermalactivity is still observed in the form of fumaroles opening onto the surface as emission of lowtemperature(50–90°C) vapor and gases [7]. The samples were collected aseptically in the course of the joint Spanish–Russian Antarctic expedition in 2009 as described earlier [8] and delivered to the laboratory in the frozenstate. A total of three wells were drilled for sampling ona plane ground (62°59′7.40′′ S, 60°40′43.00′′ W) nearCrater Lake, and four samples from the depths of 1.0–1.8 m of the permafrost at least 180 years old wereinvestigated [9].Enumeration of thermophilic bacteria and theirsubsequent isolation were carried out on solid nutrientmedia TSA (Fluka) and R2A (Sigma) at 55°C, pH 7.0.The pure cultures were incubated under aerobic conditions in the 35–80°C range. The morphological,physiological, and biochemical features of the cellswere studied using the generally accepted methods[10]. In order to determine the 16S rRNA genesequence and the G+C composition, DNA was isolated according to Marmur [11]. Amplification of the16S rRNA gene was carried out with the universal bacterial primers 21F and 1492R and the Encyclo PCR kitof reagents (Evrogen, Russia) on an Eppendorf MasterCycler. The DNA was sequenced at Evrogen. Preliminary analysis of the nucleotide sequences obtainedwas carried out using the BLAST software package;the MEGA5 package [12] was used for alignment andphylogenetic analysis. The nucleotide compositionwas determined using the thermal DNA denaturationmethod on the Beckman Coulter DU800 spectrophotometer with a temperaturecontrolled cell. The typestrain

A large hydrothermal reservoir beneath Taal Volcano (Philippines) revealed by magnetotelluric observations and its implications to the volcanic activity.

Taal Volcano is one of the most active volcanoes in the Philippines. The magnetotelluric 3D forward analyses indicate the existence of a large high resistivity anomaly (∼100 Ω·m) with a volume of at least 3 km × 3 km × 3 km, which is capped by a conductive layer (∼10 Ω·m), beneath the Main Crater. This high resistivity anomaly is hypothesized to be a large hydrothermal reservoir, consisting of the aggregate of interconnected cracks in rigid and dense host rocks, which are filled with hydrothermal fluids coming from a magma batch below the reservoir. The hydrothermal fluids are considered partly in gas phase and liquid phase. The presence of such a large hydrothermal reservoir and the stagnant magma below may have influences on the volcano’s activity. Two possibilities are presented. First, the 30 January 1911 explosion event was a magmatic hydrothermal eruption rather than a base-surge associated with a phreato-magmatic eruption. Second, the earlier proposed four eruption series may be better interpreted by two cycles, each consisting of series of summit and flank eruptions.

The ~ 31 ka rhyolitic Plinian to sub-Plinian eruption of Tlaloc Volcano, Sierra Nevada, central Mexico

Tlaloc is a late Pleistocene stratovolcano located NE of México City. It is the northernmost volcano of the N–S Sierra Nevada Volcanic Range, which consists from north to south of Tlaloc, Telapón, Iztaccíhuatl, and Popocatépetl volcanoes. Tlaloc has always been considered the oldest (and extinct) volcano of the Sierra Nevada Volcanic Range. Recent field data revealed that Tlaloc was very active during late Pleistocene through a series of explosive eruptions. One of these eruptions produced the Multilayered White Pumice (MWP) a rhyolitic pyroclastic sequence. The eruption began with a 24-km high Plinian column MWP-F1 that was dispersed to the NE by prevailing winds. It was interrupted by fountaining of the column with the generation of a pyroclastic density current that emplaced MWP-S1 layer. Then, followed five unstable sub-Plinian columns (MWP-F2 to F6) that reached altitudes between 16 and 19km. Fall deposits as a whole are 1m thick at 12km from the vent, cover a minimum area of 577km2 for a total volume of 4.68km3 (DRE 1.58km3). The eruption ejected a total mass of 3.45×1012kg at different mass discharges. The last sub-Plinian column (MWP-F6) collapsed and produced dense pyroclastic density currents that deposited pumiceous pyroclastic flows (MWP-PF) following main ravines to the north and east of the vent. These density currents filled gullies with 23m-thick deposits at a distance of 12km from the vent totaling a minimum DRE volume of 0.2km3. Pyroclastic flow deposits charred tree trunks that yielded an age of 31,490+1995/−1595yrB.P. that closely date the age of the eruption. Rain during this phase of the eruption generated syn-eruptive lahars (MWP-DF). Post-eruptive lahars (MWP-ED) finally swept the volcano flanks.The MWP deposits consist of abundant white pumice (up to 96vol.%), rare gray pumice, cognate lithics, accidental altered lithics, xenocrysts. White and gray pumice clasts contain phenocrysts of quartz, plagioclase, sanidine, biotite, rare Fe–Ti oxides, monazite, zircon and apatite. Xenocrysts are represented by plagioclase, microcline, orthoclase and quartz likely coming from a deeper plutonic body. Both pumices have a rhyolitic composition (74.98±1wt.% SiO2 in water free basis) representing one of the most acidic products of Tlaloc and the entire Sierra Nevada Volcanic Range. The rhyolitic liquid was likely extracted from a mush-like plutonic body reaching the minimum predicted vesicularity values for Plinian fragmentation for which the triggering mechanism of the MWP eruption is attributed to the high viscosity of the magma that provoked overpressure of the magmatic system. The parameters studied suggest that eruption behavior evolved from Plinian to sub-Plinian eruptive columns over time due to conduit dynamics rather than variations in magma properties of the MWP products.

Reflectance confocal microscopy characteristics of eight cases of pustular eruptions and histopathological correlations

Reflectance confocal microscopy (RCM)'s interest has been well established for the non-invasive diagnosis of skin cancers, especially melanocytic, and in the differential diagnosis between benign and malignant cutaneous lesions. However, its diagnostic interest in inflammatory skin diseases still needs to be demonstrated. Our purpose was to evaluate the correlation between RCM and conventional histopathology in a series of pustular eruptions of different pathogeny. Reflectance confocal microscopy analysis was performed in eight consecutive unselected patients in whom the diagnoses of pustular psoriasis, bacterial sur-infection, herpes-type virus skin sur-infection, Sneddon-Wilkinson subcorneal putulosis and Hailey-Hailey disease have been made and images were compared to conventional histopathology. Neutrophils within the epidermis exhibited never reported earlier specific features, with either a shiny granular sludge or polylobated particules with a bright granular content. Moreover, some specific etiologies could be identified, such as acantholysis and herpes-type virus-infected keratinocytes. Our studies show a good correlation between RCM and conventional histopathology in pustular eruptions. Reflectance confocal microscopy may play an important role in the differential diagnosis of pustular eruptions; as most of the pathologic clues are epidermal, narrow thickness of the field of imaging, its main technical limitation, is indeed of lesser importance.

Post-glacial time series of explosive eruptions and associated changes in the magma plumbing system of Lonquimay volcano, south central Chile

The Lonquimay volcanic complex (LVC) in the high Southern Andes comprises a stratocone and NE-trending flank-cone alignments. Numerous effusive and explosive volcanic eruptions characterize its post-glacial magmatic activity. Our tephrostratigraphic record, pre-dating the four historically documented eruptions, comprises 22 dated pyroclastic deposits that are used to constrain repose time distribution and eruption probability of the LVC magmatic system. Statistical examination of the stratigraphy-based eruption time series yields probabilities of 20–50 % for at least one explosive (VEI ≥ 3) eruption within the next 100 years as of 2011. The tephra deposits are subdivided into three petrographic groups: a felsic group (Lonquimay colored-pumice tephra, LCPT), an intermediate population (Lonquimay gray pumice tephra, LGPT), and a mafic member (Lonquimay dark scoria tephra, LDST). The distribution of these petrographic groups through the LVC tephrostratigraphy is linked to the observed changes in repose times. LDST-deposits as well as deposits compositionally zoned from LCPT to LGPT dominate the lower part of the stratigraphy for which recurrence times are short (RTmean = 417 ± 169a). Deposits younger than 6,000 b2k (years before 2000 AD) have dominantly LCPT and minor LDST compositions, no longer contain LGPT, and repose times are significantly longer (RTmean = 1,350 ± 310a). We interpret the change in eruption regime to result from a rearrangement in the magma storage and plumbing system. Thermobarometric calculations based on cpx–liquid equilibria and amphibole compositions reveal three distinct magma storage levels: the mafic LDST derive from mid crustal storage (P mean = 476 ± 95 MPa, T mean = 1,073 ± 24 °C), felsic LCPT mainly erupted from upper-crustal level (P mean = 86 ± 49 MPa, T mean = 936 ± 24 °C), whereas LGPT samples yield intermediate storage depths (P mean = 239 ± 100 MPa, T mean = 1,013 ± 17 °C). Magma contributions from this intermediate reservoir are restricted to >6,000 b2k when the Lonquimay plumbing system was in a regime of short repose times; disappearance of the intermediate reservoir coincides with the change to longer repose times between eruptions.

Yellowstone's Deep Roots

Geophysics![Figure][1] CREDIT: THINKSTOCK Yellowstone National Park in the western United States, renowned for its geothermal features, including geysers and hot springs, rests on a ∼4000-km2 caldera attributed to a series of supervolcano eruptions over the past 2 million years. The volcanic and geothermal activity is caused by the presence of a hot spot currently resting below the park that migrated eastward over the course of millions of years. Conflicting geological evidence implies that the source of this hotspot volcanism is either a deep plume originating hundreds of km below Earth's surface in the lower mantle or more shallow upper mantle melting caused primarily by extension of the continental lithosphere—a process that occurs elsewhere in the western United States. Schmandt et al. , analyzing data collected by the dense USArray seismic network while it was deployed across the region, addressed this debate through seismic imaging of the mantle below Yellowstone. Comparing the temperature-sensitive depth variation of mantle discontinuities at 410 and 660 km to global averages indicates the presence of a high-temperature upwelling that is vertically heterogeneous. The shallowing of the 660-km discontinuity, which marks the boundary between the upper and lower mantle, suggests that this plume-like structure originates in the lower mantle, but just how deep down remains unclear. Earth Planet. Sci. Lett. 10.1016/j.epsl.2012.03.025 (2012). [1]: pending:yes

Inferring phases of thermal unrest at Mt. Asama (Japan) from infrared satellite observations

On 1 September 2004 a vulcanian eruption, the strongest since 1983, occurred at Mt. Asama, one of the most active volcanoes in Japan. An ash plume that rose 2km above the crater was emitted, together with incandescent blocks ejected several kilometers away from the summit crater. Subsequently, after a short quiescence period of about 2weeks, a series of minor eruptions took place from 14 September. They were considered unusual for Mt. Asama for the presence of juvenile material dominant among fallout. Small and moderate eruptions continued even in the following months to end in December 2004. On the basis of GPS observations, a dike intrusion occurred under the western flank of Mt. Asama about 6weeks before 1 September eruption, triggering the magma ascension towards the surface. This phenomenon produced many signs of unrest including a thermal activity observed on the ground from the end of July 2004. The retrospective analysis presented in this paper, performed applying the RSTVOLC algorithm to Moderate Resolution Imaging Spectroradiometer (MODIS) data, shows the occurrence of pre-eruptive hot spots at Mt. Asama during 1–31 August and 11–12 September 2004. These results extend observations of a previous MODIS-based independent study and show the occurrence of a distinct phase of thermal unrest, of short-time duration, a few days before the 14 September minor eruption. Moreover, by the temporal trend of radiative power from infrared data, time of occurrence of dome extrusion is also estimated, in good agreement with independent radar observations. These outcomes seem to be compatible with different mechanisms of upward propagation of magma speculated by previous authors, confirming the potential of infrared satellite observations in identifying thermal precursory signals of volcanic eruptions, provided that proper detection algorithms are used.

Linking Petrology and Seismology at an Active Volcano

Many active volcanoes exhibit changes in seismicity, ground deformation, and gas emissions, which in some instances arise from magma movement in the crust before eruption. An enduring challenge in volcano monitoring is interpreting signs of unrest in terms of the causal subterranean magmatic processes. We examined over 300 zoned orthopyroxene crystals from the 1980-1986 eruption of Mount St. Helens that record pulsatory intrusions of new magma and volatiles into an existing larger reservoir before the eruption occurred. Diffusion chronometry applied to orthopyroxene crystal rims shows that episodes of magma intrusion correlate temporally with recorded seismicity, providing evidence that some seismic events are related to magma intrusion. These time scales are commensurate with monitoring signals at restless volcanoes, thus improving our ability to forecast volcanic eruptions by using petrology.

In the Greek isles a volcano has awakened

In 1650 B.C.E. a series of massive volcanic eruptions decimated the ancient seafaring Minoan civilization. Over the next 4 millennia, the largely subaquatic Santorini caldera had a series of smaller eruptions, with five such events within the past 600 years, ending most recently in 1950. From the air the Santorini caldera appears as a small cluster within the larger collection of Greek islands in the southern Aegean Sea. Following a 60‐year lull, Santorini woke up on 9 January 2011 with a swarm of low‐magnitude earthquakes.

Geochemical and isotopic development of the Coromandel Volcanic Zone, northern New Zealand, since 18 Ma

Cenozoic subduction-related volcanism in northern New Zealand developed from mainly basaltic and andesitic volcanisms in the Early Miocene to mainly silicic volcanism in the present Taupo Volcanic Zone. The first explosive silicic eruptions occurred at 12Ma and large silicic calderas formed from 8Ma. This transition is recorded by the 18–1.9Ma Coromandel Volcanic Zone (CVZ) succession, which provides an outstanding opportunity to investigate the origins of the modern North Island volcanism. New major and trace element data on a rock suite representing CVZ andesites, rhyolites and basalts indicate a consistent subduction-related origin for the entire succession. The CVZ andesites generally define a consistent medium-potassic differentiation trend, however, distinct andesites with relatively sodic compositions occur at the bases of two consecutive eruptive series at ~18 and ~10Ma. The distinct andesites are geochemically similar to basalts that erupted sporadically near the oceanic margin of the CVZ. CVZ rhyolites are medium- to high-potassic, peraluminous rocks with initial 87Sr/86Sr values comparable to or somewhat more radiogenic than coeval andesites (≥0.7049). Their bulk rock composition suggests derivation from sources comparable to least-differentiated andesites or basalts. We interpret the consecutive andesitic successions to represent stages in CVZ development during which distinct arc segments developed consecutively. The early stage in each segment yielded mainly intermediate volcanism whereas in the later stage volcanism locally proceeded rapidly (within ~1Myr of initial andesitic activity) to silicic activity. Taken together, the succession records the rapid development and migration of arc system in a dynamic plate boundary setting.

Lidar Observations of Aerosol Disturbances of the Stratosphere over Tomsk (56.5∘N;85.0∘E) in Volcanic Activity Period 2006–2011

The lidar measurements (Tomsk:56.5∘N;85.0∘E) of the optical characteristics of the stratospheric aerosol layer (SAL) in the volcanic activity period 2006–2011 are summarized and analyzed. The background SAL state with minimum aerosol content, observed since 1997 under the conditions of long-term volcanically quiet period, was interrupted in October 2006 by series of explosive eruptions of volcanoes of Pacific Ring of Fire: Rabaul (October 2006, New Guinea); Okmok and Kasatochi (July-August 2008, Aleutian Islands); Redoubt (March-April 2009, Alaska); Sarychev Peak (June 2009, Kuril Islands); Grimsvötn (May 2011, Iceland). A short-term and minor disturbance of the lower stratosphere was also observed in April 2010 after eruption of the Icelandic volcano Eyjafjallajokull. The developed regional empirical model of the vertical distribution of background SAL optical characteristics was used to identify the periods of elevated stratospheric aerosol content after each of the volcanic eruptions. Trends of variations in the total ozone content are also considered.

SYMPATHETIC FILAMENT ERUPTIONS FROM A BIPOLAR HELMET STREAMER IN THE SUN

On 2005 August 5, two solar filaments erupted successively from different confined arcades underlying a common overarching multiple-arcade bipolar helmet streamer. We present detailed observations of these two events and identify them as sympathetic filament eruptions. The first (F1) is a small active-region filament located near the outskirts of the streamer arcade. It underwent a nonradial eruption, initially moving in the interior of the streamer arcade and resulting in an over-and-out coronal mass ejection. The second filament (F2), a larger quiescent one far away from F1, was clearly disturbed during the F1 eruption. It then underwent a very slow eruption and finally disappeared completely and permanently. Because two belt-shaped diffuse dimmings formed along the footprints of the streamer arcade in the first eruption and persisted throughout the complete disappearance of F2, the eruption series are interpreted as sympathetic: the simple expansion of the common streamer arcade forced by the F1 eruption weakened magnetic flux overlying F2 and thus led to its slow eruption, with the dimming formation indicating their physical connection. Our observations suggest that multiple-arcade bipolar helmet-streamer configurations are appropriate to producing sympathetic eruptions. Combined with the recent observations of unipolar-streamer sympathetic events, it appears that a multiple-arcade unipolar or bipolar helmet streamer can serve as a common magnetic configuration for sympathetic eruptions.

Search for possible relationship between volcanic ash particles and thunderstorm lightning activity

Explosive volcanic eruptions that eject columns of ash from the crater often generate lightning discharges strong enough to be remotely located by very low frequency radio waves. A fraction of volcanic ash particles can stay and disperse long enough to have an effect on weather phenomena days later such as thunderstorms and lightnings. In this work we report on lightning activity analysis over Europe following two recent series of volcanic eruptions in order to identify possible correlations between ash release and subsequent thunderstorm flash frequency. Our attempts gave negative results which can be related to the fact that we have limited information on local atmospheric variables of high enough resolution, however lightning frequency is apparently determined by very local circumstances.

Volcanic impact on the Atlantic Ocean over the last millennium

Abstract. The oceanic response to volcanic eruptions over the last 1000 years is investigated with a focus on the North Atlantic Ocean, using a fully coupled AOGCM forced by a realistic time series of volcanic eruptions, total solar irradiance (TSI) and atmospheric greenhouse gases concentration. The model simulates little response to TSI variations but a strong and long-lasting thermal and dynamical oceanic adjustment to volcanic forcing, which is shown to be a function of the time period of the volcanic eruptions. The thermal response consists of a fast tropical cooling due to the radiative forcing by the volcanic eruptions, followed by a penetration of this cooling in the subtropical ocean interior one to five years after the eruption, and propagation of the anomalies toward the high latitudes. The oceanic circulation first adjusts rapidly to low latitude anomalous wind stress induced by the strong cooling. The Atlantic Meridional Overturning Circulation (AMOC) shows a significant intensification 5 to 10 years after the eruptions of the period post-1400 A.D., in response to anomalous atmospheric momentum forcing, and a slight weakening in the following decade. In response to the stronger eruptions occurring between 1100 and 1300, the AMOC shows no intensification and a stronger reduction after 10 years. This study thus stresses the diversity of AMOC response to volcanic eruptions in climate models and discusses possible explanations.

Eruptive scenarios of phonolitic volcanism at Teide–Pico Viejo volcanic complex (Tenerife, Canary Islands)

Recent studies on Teide–Pico Viejo (TPV) complex have revealed that explosive activity of phonolitic and basaltic magmas, including plinian and subplinian eruptions, and the generation of a wide range of pyroclastic density currents (PDCs) have also been significant. We perform a statistical analysis of the time series of past eruptions and the spatial extent of their erupted products, including lava flows, fallout and PDCs. We use an extreme value theory statistical method to calculate eruption recurrence. The analysis of past activity and extent of some well-identified deposits is used to calculate the eruption recurrence probabilities of various sizes and for different time periods. With this information, we compute several significant scenarios using the GIS-based VORIS 2 software (Felpeto et al., J Volcanol Geotherm Res 166:106–116, 2007) in order to evaluate the potential extent of the main eruption hazards that could be expected from TPV. The simulated hazard scenarios show that the southern flank of Tenerife is protected by Las Canadas caldera wall against lava flows and pyroclastic density currents, but not against ash fallout. The Icod Valley, and to a minor extent also the La Orotava valley, is directly exposed to most of TPV hazards, in particular to the gravity driven flows. This study represents a step forward in the evaluation of volcanic hazard at TPV with regard to previous studies, and the results obtained should be useful for intermediate and long-term land-use and emergency planning.

Volcanic hazard assessment for the Canary Islands (Spain) using extreme value theory

Abstract. The Canary Islands are an active volcanic region densely populated and visited by several millions of tourists every year. Nearly twenty eruptions have been reported through written chronicles in the last 600 yr, suggesting that the probability of a new eruption in the near future is far from zero. This shows the importance of assessing and monitoring the volcanic hazard of the region in order to reduce and manage its potential volcanic risk, and ultimately contribute to the design of appropriate preparedness plans. Hence, the probabilistic analysis of the volcanic eruption time series for the Canary Islands is an essential step for the assessment of volcanic hazard and risk in the area. Such a series describes complex processes involving different types of eruptions over different time scales. Here we propose a statistical method for calculating the probabilities of future eruptions which is most appropriate given the nature of the documented historical eruptive data. We first characterize the eruptions by their magnitudes, and then carry out a preliminary analysis of the data to establish the requirements for the statistical method. Past studies in eruptive time series used conventional statistics and treated the series as an homogeneous process. In this paper, we will use a method that accounts for the time-dependence of the series and includes rare or extreme events, in the form of few data of large eruptions, since these data require special methods of analysis. Hence, we will use a statistical method from extreme value theory. In particular, we will apply a non-homogeneous Poisson process to the historical eruptive data of the Canary Islands to estimate the probability of having at least one volcanic event of a magnitude greater than one in the upcoming years. This is done in three steps: First, we analyze the historical eruptive series to assess independence and homogeneity of the process. Second, we perform a Weibull analysis of the distribution of repose time between successive eruptions. Third, we analyze the non-homogeneous Poisson process with a generalized Pareto distribution as the intensity function.

Influences of the 2010 Eyjafjallajökull volcanic plume on air quality in the northern Alpine region

Abstract. A series of major eruptions of the Eyjafjallajökull volcano in Iceland started on 14 April 2010 and continued until the end of May 2010. The volcanic emissions moved over nearly the whole of Europe and were observed first on 16 April 2010 in Southern Germany with different remote sensing systems from the ground and space. Enhanced PM10 and SO2 concentrations were detected on 17 April at mountain stations (Zugspitze/Schneefernerhaus and Schauinsland) as well as in Innsbruck by in situ measurement devices. On 19 April intensive vertical mixing and advection along with clear-sky conditions facilitated the entrainment of volcanic material down to the ground. The subsequent formation of a stably stratified lower atmosphere with limited mixing near the ground during the evening of 19 April led to an additional enhancement of near-surface particle concentrations. Consequently, on 19 April and 20 April exceedances of the daily threshold value for particulate matter (PM10) were reported at nearly all monitoring stations of the North Alpine foothills as well as at mountain and valley stations in the northern Alps. The chemical analyses of ambient PM10 at monitoring stations of the North Alpine foothills yielded elevated Titanium concentrations on 19/20 April which prove the presence of volcanic plume material. Following this result the PM10 threshold exceedances are also associated with the volcanic plume. The entrainment of the volcanic plume material mainly affected the concentrations of coarse particles (>1 μm) – interpreted as volcanic ash – and ultrafine particles (<100 nm), while the concentrations of accumulation mode aerosol (0.1–1 μm) were not changed significantly. With regard to the occurrence of ultrafine particles, it is concluded that their formation was triggered by high sulphuric acid concentrations which are necessarily generated by the photochemical processes in a plume rich in sulphur dioxide under high solar irradiance. It became evident that during the course of several days, the Eyjafjallajökull volcanic emissions influenced the near-surface atmosphere and thus the ambient air quality. Although the volcanic plume contributed to the overall exposure of the population of the northern Alpine region on two days, only minor effects on the exacerbation of respiratory and cardiovascular symptoms can be expected.