Showing papers on "Phreatomagmatic eruption published in 2009"
TL;DR: Fossiliferous rocks from southwest China show that a major extinction in the Middle Permian coincided with extensive volcanic eruptions, and the onset of volcanism was marked by both large phreatomagmatic eruptions and extinctions amongst fusulinacean foraminifers and calcareous algae.
Abstract: The 260-million-year-old Emeishan volcanic province of southwest China overlies and is interbedded with Middle Permian carbonates that contain a record of the Guadalupian mass extinction. Sections in the region thus provide an opportunity to directly monitor the relative timing of extinction and volcanism within the same locations. These show that the onset of volcanism was marked by both large phreatomagmatic eruptions and extinctions amongst fusulinacean foraminifers and calcareous algae. The temporal coincidence of these two phenomena supports the idea of a cause-and-effect relationship. The crisis predates the onset of a major negative carbon isotope excursion that points to subsequent severe disturbance of the ocean-atmosphere carbon cycle.
286 citations
TL;DR: In this article, the authors use the historic earthquake and eruption records of Chile and the Andean southern volcanic zone to investigate eruption rates following large earthquakes, showing that both dynamic and static stresses associated with large earthquakes are important in eruption-triggering processes and have the potential to initiate volcanic eruption in arc settings over timescales of several months.
97 citations
TL;DR: Tecuitlapa Maar as discussed by the authors is a late Quaternary, 100m-deep, > 1 km-diameter crater with an alignment of scoria cones, building in height to the east, within it.
94 citations
TL;DR: The Croscat pyroclastic succession has been analyzed to investigate the transition between different eruptive styles in basaltic monogenetic volcanoes, with particular emphasis on the role of phreatomagmatism in triggering Violent Strombolian eruptions as mentioned in this paper.
83 citations
24 Mar 2009
TL;DR: In this article, an explosive eruption discharging = l0 6 kgs -1 of basaltic magma occurred in Karymskoye lake at an initial water depth of ~ 50 m. The most widespread hazards of the eruption were tsunamis and lahars.
Abstract: On 2-3 January 1996 an explosive eruption discharging = l0 6 kgs -1 of basaltic magma occurred in Karymskoye lake at an initial water depth of ~ 50 m. Characteristics of the deposits together with analyses of a videotape of several explosions have allowed us to model the eruptive events. Initial vent-clearing phreatic explosions ejected blocks of country rocks (up to 3 m diameter) to distances of up to 1.3 km. Then followed 10- 20 h of phreatomagmatic Surtseyan activity (100-200 outbursts of water-gas-pyroclastic mixtures to heights of up to 1 km, with initial velocities of 110 m s -1 |. The eruption slugs collapsed back into the lake and produced base surges (runout up to 1.3 km; average velocity 12.5 m s -1 ). The convective eruption plume rose to a height of 3 km and deposited a thin distal fall deposit. The eruption ended with the ejection of scoria-crust bombs (specific basaltic bombs with dense core and scoriaceous crust). Pyroclasts of the eruption are mostly poorly to moderately vesicular juvenile basaltic particles shaped by a combination of magmatic vesiculation and magma-water interaction. Ninety-five percent of the products (0.047 km 3 ) formed an underwater tuff ring composed of parallel layers of moderately to poorly sorted lapilli ash and ash lapilli (Md - 3.9 to 0.6 phi; sorting 1.5-3.2 phi), each 10-60 cm thick. They were deposited by water-rich base surges that originated from Surtseyan type eruption bursts. The most widespread hazards of the eruption were tsunamis and lahars. At distances < 1.3 km from the crater, base surges and ballistic clasts were very destructive. Eruptive activity in the lake before 1996 included two eruptions at c. 4800 14 C yr BP. The first left deposits similar to those of the 1996 eruption and thus is interpreted as a Surtseyan eruption that occurred at the same water depth as in 1996. The second of the 4800 l4 C yr BP eruptions deposited extensive cross-laminated base-surge deposits and is interpreted to have occurred in very shallow water.
79 citations
TL;DR: In this article, the authors investigated the role of external water in the phreatoplinian phase of the Askja eruption and found that it was a foam prior to fragmentation.
64 citations
TL;DR: In this paper, the authors show that the 1974 western flank eruption of Mount Etna produced a rare, nearly aphyric and plagioclase-free trachybasalt that could not be derived from the central volcano conduits and was more alkaline and more radiogenic than all previous historical lavas.
Abstract: [1] The 1974 western flank eruption of Mount Etna produced a rare, nearly aphyric and plagioclase-free trachybasalt that could not be derived from the central volcano conduits and was more alkaline and more radiogenic than all previous historical lavas. New results for the petrochemistry and volatile content of its products, combined with contemporaneous seismic and volcanological observations, allow us to reinterpret the origin and significance of this event. We show that the eruption was most likely triggered by deep tectonic fracturing that allowed a dike-like intrusion to propagate in 9 days from ≥11 km depth up to the surface, bypassing the central conduits. Relatively fast, closed system decompression of the volatile-rich magma initially led to lava fountaining and the rapid growth of two pyroclastic cones (Mounts De Fiore), followed by Strombolian activity and the extrusion of viscous lava flows when gas-melt separation developed in the upper portion of the feeding fracture. The 1974 trachybasalt geochemistry indicates its derivation by mixing 25% of preexisting K-poor magma (best represented by 1763 La Montagnola eruption's products) and 75% of a new K-rich feeding magma that was gradually invading Mount Etna's plumbing system and became directly extruded during two violent flank eruptions in 2001–2003. We propose to classify 1974-type so-called “eccentric” eruptions on Etna as deep dike-fed (DDF) eruptions, as opposed to more common central conduit-fed flank eruptions, in order to highlight their actual origin rather than their topographic location. We ultimately discuss the possible precursors of such DDF eruptions.
59 citations
TL;DR: In this paper, a detailed study of the deposits from Montana Los Erales, a 70m-high Quaternary cinder cone belonging to a rift-related chain of vents in the Bandas del Sur region, in Southeast Tenerife, was undertaken.
52 citations
TL;DR: The Table Rock Complex (TRC) as mentioned in this paper is a large and well-exposed mafic phreatomagmatic complex in the Fort Rock-Christmas Lake valley basin, south-central Oregon.
51 citations
TL;DR: In the Campo de Calatrava Volcanic Field (CCVF, Central Spain), the eruption of Pliocene-Pleistocene maar craters into two clearly distinct types of pre-volcanic rocks allows the observation and comparison of hard-substrate and soft-surface maar lakes.
49 citations
TL;DR: Barren Island (India) is a relatively little studied, little known active volcano in the Andaman Sea, and the northernmost active volcano of the great Indonesian arc.
Abstract: Barren Island (India) is a relatively little studied, little known active volcano in the Andaman Sea, and the northernmost active volcano of the great Indonesian arc. The volcano is built of prehistoric (possibly late Pleistocene) lava flows (dominantly basalt and basaltic andesite, with minor andesite) intercalated with volcaniclastic deposits (tuff breccias, and ash beds deposited by pyroclastic falls and surges), which are exposed along a roughly circular caldera wall. There are indications of a complete phreatomagmatic tephra ring around the exposed base of the volcano. A polygenetic cinder cone has existed at the centre of the caldera and produced basalt-basaltic andesite aa and blocky aa lava flows, as well as tephra, during historic eruptions (1787–1832) and three recent eruptions (1991, 1994–95, 2005–06). The recent aa flows include a toothpaste aa flow, with tilted and overturned crustal slabs carried atop an aa core, as well as locally developed tumuli-like elliptical uplifts having corrugated crusts. Based on various evidence we infer that it belongs to either the 1991 or the 1994–95 eruptions. The volcano has recently (2008) begun yet another eruption, so far only of tephra. We make significantly different interpretations of several features of the volcano than previous workers. This study of the volcanology and eruptive styles of the Barren Island volcano lays the ground for detailed geochemical-isotopic and petrogenetic work, and provides clues to what the volcano can be expected to do in the future.
TL;DR: In this paper, the authors distinguish two facies within the Masaya Triple Layer from each other: La Concepcion facies to the south and Managua facies in the northwest.
TL;DR: The Plinian Lower Pumice 2 (LP2) eruption was one of the first major caldera-forming eruptions of the Santorini volcanic complex (Greece) as mentioned in this paper.
TL;DR: In this article, a multidisciplinary project was launched for studying the hydrothermal activity of Taal volcano in the Philippines, and combined surveys were carried out to investigate self-potential, total magnetic field, ground temperature and carbon dioxide soil degassing, along with satellite thermal imaging of the Main Crater Lake.
Abstract: Since 1572, 33 phreatic to phreatomagmatic eruptions have occurred on Taal volcano (Philippines), some of them causing several hundred casualties. Considering the time delay between two consecutive eruptions, there is an 88% probability that Taal volcano should have already erupted. Since 1992, several phases of seismic activity have been recorded accompanied by ground deformation, opening of fissures, and surface activity. The volcanic activity of Taal appears to be controlled by dike injections and magma supply, buffered by a hydrothermal system that releases fluids and heat through boiling and subsequent steaming. In early 2005, a multidisciplinary project was launched for studying the hydrothermal activity. To map the hydrothermal system, combined surveys were carried out to investigate self-potential, total magnetic field, ground temperature and carbon dioxide soil degassing, along with satellite thermal imaging of the Main Crater Lake. The elevated temperatures and high concentrations of carbon dioxide, as well as electromagnetic anomalies, indicate large-scale hydrothermal degassing. This process is enhanced along the tectonic features (e.g., crater rim and faults) of the volcano, while active fissures opened along the E–W northern flank during the 1992–1994 seismic activity. Heat and fluids from the hydrothermal system are essentially released in the northern part of the crater, which is bounded to the South by a suspected NW–SE fault along which seismicity seems to take place, and dikes are thought to be intruded. During the January 2005 surveys, a new seismic crisis started, and the felt earthquakes prompted spontaneous evacuation of hundreds of inhabitants living on the volcano. Repeated surveys show changes of self-potential, total magnetic field, and ground temperature with time, without any noticeable spatial enlargement. These observations suggest that the northern flank located between the crater rim and the 1992–1994 fissures is connected with a deep thermal source in Main crater and is reactivated during seismic crises. This sector could be subjected to flank failure.
TL;DR: In this paper, three eruptive episodes during the 2006 summit eruptions of Mount Etna were exceptionally well documented by visual, seismic, and thermal monitoring, which provides a key to distinguish between endogenous and exogenous origins of the phenomena observed and documents the complex magma dynamics within the volcano.
Abstract: [1] Three eruptive episodes during the 2006 summit eruptions of Mount Etna were exceptionally well documented by visual, seismic, and thermal monitoring. The first (16 November) was strongly explosive, with vigorous Strombolian activity and ash emission from multiple vents, lava emission, and phreatomagmatic explosions generating pyroclastic density currents (PDCs). The second episode (19 November) had a rather weakly explosive component, with mild Strombolian activity but more voluminous lava emission. The third (24 November) was a moderately explosive paroxysm, with intermittent lava fountaining and generation of a tephra column as well as lava emission and PDCs. Data recorded by a thermal monitoring camera clearly document the different phases of each paroxysm, weather clouds occasionally hampering thermal monitoring. The images show a rapid onset of the volcanic activity, which during each of the paroxysms reached a peak in eruptive and thermal intensity and then decreased gradually. The stronger phreatomagmatic explosions and PDCs on 16 and 24 November did not yield any seismic signature linked to the opening of new vents nor were they associated with peculiar characteristics of the seismic signal. Nevertheless, eruptive styles (Strombolian activity, lava emission) and different levels in the intensity of explosive activity were generally well reflected in the amplitude and frequency content of the seismic signal and in the source location of the volcanic tremor centroid throughout the three eruptive episodes. This multidisciplinary study, therefore, not only provides a key to distinguish between endogenous and exogenous origins of the phenomena observed but also documents the complex magma dynamics within the volcano.
TL;DR: In this paper, the authors used radiocarbon ages and extensive geological fieldwork to show that during the past 11ka 24 monogenetic basaltic eruptions occurred in the north sector of Gran Canaria.
Abstract: Previous published data, combined with our results of 13 new radiocarbon ages and extensive geological fieldwork, indicate that during the past 11 ka 24 monogenetic basaltic eruptions occurred in the north sector of Gran Canaria. These eruptions can be grouped into three periods of eruptive activity: 1900–3200 14C a BP; 5700–6000 14C a BP; and an older period represented by only one eruption, El Draguillo, dated at 10 610 ± 190 14C a BP. Archaeological studies have shown that the more recent eruptions affected prehistoric human settlements on the island. Field studies demonstrate that the eruptions typically built strombolian cones (30–250 m in height) and associated relatively long lava flows (100–10 350 m in length); a few eruptions also produced tephra fall deposits. The total erupted volume of these eruptions is about 0.388 km3 (46.1% as tephra fall, 41.8% as cinder cone deposits and 12.1% as lava flows). The relatively low eruption rate (∼0.04 km3 ka−1) during the past 11 ka is consistent with Gran Canaria's stage of evolution in the regional volcano-tectonic setting of the Canary Archipelago. The results of our study were used to construct a volcanic hazards map that clearly delimits two sectors in the NE sector of Gran Canaria, where potential future eruptions would pose a substantial risk for densely populated areas. Copyright © 2009 John Wiley & Sons, Ltd.
TL;DR: In this article, a review summarises research undertaken during the last decade and provides a new summary of the distribution of rhyolitic glaciovolcanic rocks erupted during the past 0.8 Ma from at least fifteen volcanic systems.
TL;DR: In this article, the authors present new evidence for fresh volcanic landforms and deposits, supported by a radiocarbon date of 1915±65 years B.P., giving a maximum age to a phreatomagmatic tuff cone offshore of Cape Tapaga, east Upolu.
TL;DR: In this article, the authors presented the stratigraphy, lithology, volcanology, and age of the Acahualinca section in Managua, including a famous footprint layer exposed in two museum pits.
Abstract: We present the stratigraphy, lithology, volcanology, and age of the Acahualinca section in Managua, including a famous footprint layer exposed in two museum pits. The ca. 4-m-high walls of the main northern pit (Pit I) expose excellent cross sections of Late Holocene volcaniclastic deposits in northern Managua. We have subdivided the section into six lithostratigraphic units, some of which we correlate to Late Holocene eruptions. Unit I (1.2 m thick), chiefly of hydroclastic origin, begins with the footprint layer. The bulk is dominated by mostly massive basaltic-andesitic tephra layers, interpreted to represent separate pulses of a basically phreatomagmatic eruptive episode. We correlate these deposits based on compositional and stratigraphic evidence to the Masaya Triple Layer erupted at Masaya volcano ca. 2,120 ± 120 a B.P.. The eruption occurred during the dry season. A major erosional channel unconformity up to 1 m deep in the western half of Pit I separates Units II and I. Unit II begins with basal dacitic pumice lapilli up to 10 cm thick overlain by a massive to bedded fine-grained dacitic tuff including a layer of accretionary lapilli and pockets of well-rounded pumice lapilli. Angular nonvesicular glass shards are interpreted to represent hydroclastic fragmentation. The dacitic tephra is correlated unequivocally with the ca. 1.9-ka-Plinian dacitic Chiltepe eruption. Unit III, a lithified basaltic-andesitic deposit up to 50 cm thick and extremely rich in branch molds and excellent leaf impressions, is correlated with the Masaya Tuff erupted ca. 1.8 ka ago. Unit IV, a reworked massive basaltic-andesitic deposit, rich in brown tuff clasts and well bedded and cross bedded in the northwestern corner of Pit I, cuts erosionally down as far as Unit I. A poorly defined, pale brown mass flow deposit up to 1 m thick (Unit V) is overlain by 1–1.5 m of dominantly reworked, chiefly basaltic tephra topped by soil (Unit VI). A major erosional channel carved chiefly between deposition of Units II and I may have existed as a shallow drainage channel even prior to deposition of the footprint layer. The swath of the footprints is oriented NNW, roughly parallel to, and just east of, the axis of the channel. The interpretation of the footprint layer as the initial product of a powerful eruption at Masaya volcano followed without erosional breaks by additional layers of the same eruptive phase is strong evidence that the group of 15 or 16 people tried to escape from an eruption.
TL;DR: The Asososca Tephra comprises the asymmetrically distributed, well-stratified phreatomagmatic products of the 1245 +−125/−120-yr BP Asossoca maar eruption West of Managua, Nicaragua as discussed by the authors.
TL;DR: In this article, field, geochronologic and geochemical evidence from proximal fine-grained tephras, and from limited exposures of Holocene lava flows and a small pyroclastic flow document ten-to-12 eruptions of Mount Rainier over the last 2,600 years.
Abstract: Field, geochronologic, and geochemical evidence from proximal fine-grained tephras, and from limited exposures of Holocene lava flows and a small pyroclastic flow document ten–12 eruptions of Mount Rainier over the last 2,600 years, contrasting with previously published evidence for only 11–12 eruptions of the volcano for all of the Holocene. Except for the pumiceous subplinian C event of 2,200 cal year BP, the late-Holocene eruptions were weakly explosive, involving lava effusions and at least two block-and-ash pyroclastic flows. Eruptions were clustered from ∼2,600 to ∼2,200 cal year BP, an interval referred to as the Summerland eruptive period that includes the youngest lava effusion from the volcano. Thin, fine-grained tephras are the only known primary volcanic products from eruptions near 1,500 and 1,000 cal year BP, but these and earlier eruptions were penecontemporaneous with far-traveled lahars, probably created from newly erupted materials melting snow and glacial ice. The most recent magmatic eruption of Mount Rainier, documented geochemically, was the 1,000 cal year BP event. Products from a proposed eruption of Mount Rainier between AD 1820 and 1854 (X tephra of Mullineaux (US Geol Surv Bull 1326:1–83, 1974)) are redeposited C tephra, probably transported onto young moraines by snow avalanches, and do not record a nineteenth century eruption. We found no conclusive evidence for an eruption associated with the clay-rich Electron Mudflow of ∼500 cal year BP, and though rare, non-eruptive collapse of unstable edifice flanks remains as a potential hazard from Mount Rainier.
TL;DR: In this article, an integrated approach involving volcanology, geochemistry and numerical modeling has enabled the reconstruction of the volcanic history of the Fox kimberlite pipe, where the observed deposits within the vent include a basal massive, poorly sorted, matrix supported, lithic fragment rich, column collapse lapilli tuff.
TL;DR: In this article, the hazards from various types of pyroclastic density currents (PDCs) have until now received virtually no attention at this volcano, despite the recent recognition of Mount Etna as a periodically violently explosive volcano.
TL;DR: In this article, Beus et al. characterized the phreatomagmatic deposits at Narbona Pass, a mid-Tertiary maar in the Navajo volcanic field (NVF), in order to reconstruct the evolution and dynamic conditions of the eruption.
Abstract: Phreatomagmatic deposits at Narbona Pass, a mid-Tertiary maar in the Navajo volcanic field (NVF), New Mexico (USA), were characterized in order to reconstruct the evolution and dynamic conditions of the eruption. Our findings shed light on the temporal evolution of the eruption, dominant depositional mechanisms, influence of liquid water on deposit characteristics, geometry and evolution of the vent, efficiency of fragmentation, and the relative importance of magmatic and external volatiles. The basal deposits form a thick (5–20 m), massive lapilli tuff to tuff-breccia deposit. This is overlain by alternating bedded sequences of symmetrical to antidune cross-stratified tuff and lapilli tuff; and diffusely-stratified, clast-supported, reversely-graded lapilli tuffs that pinch and swell laterally. This sequence is interpreted to reflect an initial vent-clearing phase that produced concentrated pyroclastic density currents, followed by a pulsating eruption that produced multiple density currents with varying particle concentrations and flow conditions to yield the well-stratified deposits. Only minor localized soft-sediment deformation was observed, no accretionary lapilli were found, and grain accretion occurs on the lee side of dunes. This suggests that little to no liquid water existed in the density currents during deposition. Juvenile material is dominantly present as blocky fine ash and finely vesiculated fine to coarse lapilli pumice. This indicates that phreatomagmatic fragmentation was predominant, but also that the magma was volatile-rich and vesiculating at the time of eruption. This is the first study to document a significant magmatic volatile component in an NVF maar-diatreme eruption. The top of the phreatomagmatic sequence abruptly contacts the overlying minette lava flows, indicating no gradual drying-out period between the explosive and effusive phases. The lithology of the accidental clasts is consistent throughout the vertical pyroclastic stratigraphy, suggesting that the diatreme eruption did not penetrate below the base of the uppermost country rock unit, a sandstone aquifer ∼360 m thick. By comparison, other NVF diatremes several tens of kilometers away were excavated to depths of ∼1,000 m beneath the paleosurface (e.g., Delaney PT. Ship Rock, New Mexico: the vent of a violent volcanic eruption. In: Beus SS (ed) Geological society of America Centennial Field Guide, Rocky Mountain Section 2:411–415 (1987)). This can be accounted for by structurally controlled variations in aquifer thickness beneath different regions of the volcanic field. Variations in accidental clast composition and bedding style around the edifice are indicative of a laterally migrating or widening vent that encountered lateral variations in subsurface geology. We offer reasonable evidence that this subsurface lithology controlled the availability of external water to the magma, which in turn controlled characteristics of deposits and their distribution around the vent.
TL;DR: Ambae Island is a mafic stratovolcano located in the northern Vanuatu volcanic arc and has a NE-SW rift-controlled elongated shape.
TL;DR: In this paper, the authors studied the juvenile components (scoria and pumice) of pyroclastic deposits from the Secche di Lazzaro (SDL) phreatomagmatic activity with the associated Neostromboli sector collapse.
TL;DR: In this paper, Eocene intrusion of alkaline basaltic to trachyandesitic magmas into unlithified, Upper Cretaceous to Eocene fluvial strata in part of the Trans-Pecos igneous province in West Texas produced an array of features recording both nonexplosive and explosive magma/wet-sediment interaction.
TL;DR: In this article, it was shown that the 3D structure of the erosional remnant of 71 Gulch Volcano does not require the presence of a lake at the time of its formation; it is equally possible that it represents a subaerial phreatomagmatic upper conduit.
TL;DR: In this paper, an ephemeral (and proximal) outcrop at the quaternary basaltic Puig de la Garrinada cinder volcano was studied in order to decipher eruptive mechanism variations in the course of a single eruption.
TL;DR: The Orion South kimberlite body in the Fort a la Corne field in central Saskatchewan has been investigated in this paper, where the authors found a wide variety of primary pyroclastic, volcaniclastic and re-sedimented volcanic lastic deposits.