Eruption Of February Research Articles

Eruption dynamics of the 23 February 2013 event at Mt. Etna

Volcanic activity at Mt. Etna in the last decade has mostly been manifested by sequences of short paroxysmal episodes characterised by powerful lava fountains and high eruption columns. On the 23 February 2013, an exceptionally intense episode occurred at the New South-East Crater, producing a fountain >800 m high (among the highest ever recorded at Etna) and a ~9 km eruption column that dispersed ash >400 km from the vent. Textural and petrographic analyses of lapilli revealed that magma erupted during the high-intensity phase is characterised by low microlite contents (<7 area%), high vesicularity (76–83%), and high vesicle number densities (6–8.2 × 106 cm−3). The short-lived initial Strombolian explosions removed viscous magma from the conduit, enabling the rapid ascent of gas-rich, microlite-poor magma and the eruption of an 800 m high fountain and 9 km high eruption column. For the 23 February eruption, the high vesicularity and low microlite content of the pyroclasts support the hypothesis that volatile-rich magma was the driver of the high intensity lava fountain. This eruptive event, along with three other recent events at Etna over the last 15 years, can be defined as subplinian based on eruption rate and column height, but also generated incandescent 800–1000 m fountains. For these reasons, we propose to term this event, and others at Etna characterised by similar eruption features and parameters, as subplinian fountaining events.

Ground deformation measurement of Sinabung vulcano eruption using DInSAR technique

Mt Sinabung has been erupting and spewing fumes many times in the recent year after inactive for four centuries. This paper investigates the ground deformation due to the Mt Sinabung eruption in February 2018 using Differential Interferometry Synthetic Aperture Radar Technique (DInSAR). The deformation observed and extracted from Sentinel 1A satellite data in ascending orbit that provided by Europe Space Agency (ESA). The result shows eruption direction and depth vulcanic fumes in millimeters units. This study will improve our mitigating and understanding to predict future eruption effect.

Passive monitoring of particulate matter and gaseous pollutants in Fogo Island, Cape Verde

An air quality monitoring campaign by passive sampling techniques was carried out, for the first time, between November 2016 and January 2017 on the Cape Verdean island of Fogo, whose volcanic mountain rises up to 2829 m. Levels of SO2 and acid gases (HF, HCl, HNO3, H2SO4 and H3PO4) were, in most cases, below the detection limits. Alkylpentanes, hexane, cycloalkanes and toluene were the dominant volatile organic compounds. The m,p-xylene/ethylbenzene ratios revealed that air masses arriving at Cape Verde have been subjected to significant aging processes. High toluene/benzene ratios suggested extra sources of toluene in addition to vehicle emissions. Deposition rates of total settleable dust ranged from 23 to 155 mg/m2/day. On average, organic carbon accounted for 15.6% of the dust mass, whereas elemental carbon was generally undetected. Minerals comprised the dominant mass fraction. The dust levels were mostly affected by two main airflows: the westerlies and the Saharan Air Layer. These air masses contributed to the transport of mineral dust from desert regions, secondary inorganic constituents (SO42−, NO3− and NH4+) and tracers of biomass burning emissions, such as potassium. Sea salt represented 12% of the mass of settleable dust. Scanning electron microscope observations of several particles with different compositions, shapes and sizes revealed high silica mass fractions in all samples, as well as variable contents of carbonates, sulphates, aluminosilicates, Fe, Ti, F and NaCl, suggesting that, in addition to the already mentioned sources, dust is likely linked to industrial emissions in the northern and north-western coast of the African continent. Although some atmospheric constituents presented higher concentrations near the crater, the small fumarolic activity still present after cessation of the eruption in February 2015 has a limited impact on air quality, which is most affected by long range transport and some local sources at specific locations.

Dynamic Land Resources Management at the Mount Kelud, Indonesia

There is a contradictive situation between the theory that believes that high volcanic hazard areas should be for limited production zones and those areas that are intensively utilised for several production activities. This paper tries to discuss that contradictive situation from both the perspective of natural hazards and natural resources, therefore, the best options for the land utilisation pattern might be formulated at these high volcanic hazards areas. We conducted landscape analysis that covers volcanic morphology, volcanic materials, and both natural and artificial processes that modify the morphology and materials characteristics. The natural processes occurring in the high volcanic hazard might cover non-volcanic processes such as erosion and landslide. The artificial processes were usually considered as land utilisation activities by the local community. In such areas where both natural and artificial processes occurred, we conducted in-depth interviews to assess the community perception on thread and benefits of the last Kelud Eruption in February 2014. We evaluated the current land resources utilisation and portrayed the local adaptive land resource utilisation. There were three types of land resources available at the active volcano: space, natural scenery, and volcanic materials. The availability of these land resources was in a dynamic condition both in terms of quality and quantity. Immediately after the eruption, the natural scenery made the area attractive as a tourist destination. Following the high intensity of rainfall, the volcanic materials might be used as high-quality construction materials. The available space might be utilised for any purposes after the situation became relatively stable. The current space was mostly used for agricultural enterprises which accommodates the physical and socio-cultural characteristics of the active volcano environment.

Automatic Recognition of Landslides Based on Neural Network Analysis of Seismic Signals: An Application to the Monitoring of Stromboli Volcano (Southern Italy)

In the last 9 years, the amount and the quality of geophysical and volcanological observations of Stromboli's' activity have undergone a marked increase. This new information highlighted that the landslides on the Sciara del Fuoco flank are tightly linked to the volcanic activity. Actually, at the beginning of the December 28, 2002, effusive eruption, the seismic monitoring network was less dense than now, and therefore it is not known if there was an increase in the landslide rate before the eruption. Despite this, it is known that a big landslide occurred 2 days after the beginning of the eruption which caused a tsunami (December 30, 2002). More recently, the effusive eruption in February 2007 was preceded by an increase in landslides on the Sciara del Fuoco flank, which were recorded by the seismological monitoring system that had been improved after the 2002–2003 crisis. These episodes led us to believe that monitoring the Sciara del Fuoco flank instability is an important topic, and that landslides might be significant short-term precursors of effusive eruptions at the Stromboli volcano. To automatically detect landslide signals, we have developed a specialized neural algorithm. This can distinguish between landslides and the other types of seismic signals usually recorded at the Stromboli volcano (i.e., explosion quakes and volcanic tremor). The discrimination results show an average performance of 98.67 %. According to the experience of the crisis of 2007, to identify changes that can be considered as precursors of effusive eruptions, we set up an automatic decision-making method based on the neural network responses. This method can operate on a continuous data stream. It calculates a landslide percentage index (LPI) that depends on the number of records that are classified by the net as landslides over a given time interval. We tested the method on February 27, 2007, including the beginning of the effusive phase. The index showed an increase as early as at 09:00 UTC on that day and reached its maximum value (100 %) at 12:00, about 40 min before the onset of the eruption. After the beginning of the effusive phase, the index remains high due to the blocks that roll down along the slope from the front of the lava flow. On the basis of these tests, we propose a decision-making method that is able to recognize a trend in the LPI similar to that of 2007 eruption, allowing the identification of precursors of effusive phases at the Stromboli volcano.

Structures and evolution of the plumbing system of Piton de la Fournaise volcano inferred from clustering of 2007 eruptive cycle seismicity

Analysis of seismic activity associated with the eruptions of 2007, which led to the collapse of the Dolomieu crater on April 5th, reveals the link between the seismicity and the magma transfers at Piton de la Fournaise. Three eruptive phases occurred on February 18th, March 30th and April 2nd, 2007, at the summit, 2,000 m, and 600 m high on the South-East flank respectively, illustrating the three types of eruptions defined for the current Piton de la Fournaise activity. We use cross-correlation of seismic waveforms and clustering to improve the earthquake locations and determine the best-constrained focal mechanisms (with an average of 78 P phase polarities). The pre-eruptive seismicity of the February and March eruptions is composed of time extended clusters that also preceded other distal eruptions from 2000 to 2007. Our analysis shows that the seismic swarm prior to the February eruption initiated the intrusion that led to the April 2007 eruption. The seismicity preceding the Dolomieu crater collapse consists of numerous, but time-limited, clusters and specific seismic activity that accompanied the Dolomieu crater collapse. From April 1st to April 5th, earthquakes with CLVD mechanisms combined with normal faulting sources occurred between 0.8 and 0 km asl, until the complete rupture of the shallow magma storage roof. This collapse induced the propagation of a de-pressurization front and triggered a migration of seismicity from 0 to − 8 km along a very narrow path.

Stratovolcano growth by co‐eruptive intrusion: The 2008 eruption of Tungurahua Ecuador

Volcanic edifices are constructed by a combination of erupted material and internal growth. We use the L‐band satellite ALOS to produce InSAR measurements at Tungurahua Volcano, Ecuador. We find a maximum of 17.5 cm of uplift on the upper western flank between December 2007 and March 2008, coincident with an eruption in February 2008. The deformation can be modeled using an ellipsoidal or sill‐like source within the edifice. The models require an elongated aspect ratio with a length of 4–6 km. The intruded volume of 1.2 × 106 m3 is roughly equivalent to the bulk erupted volume of 1.5 × 106 m3 and together the values are roughly equal to the long‐term magma flux. The question remains whether this uplift is permanent, thus contributing to the internal growth of the edifice, or temporary, in which case the magma will be released in a future eruption.

Trace element degassing and enrichment in the eruptive plume of the 2000 eruption of Hekla volcano, Iceland

During its last eruption in February 2000, Hekla volcano (Iceland) emitted a sub-Plinian plume that was condensed and scavenged down to the ground by heavy snowstorms, offering the unique opportunity to study the chemistry of the gaseous plume released during highly explosive eruptions. In this paper, we present results on trace element and minor volatile species (sulfates, chlorides, and fluorides) concentrations in snow samples collected shortly after the beginning of the eruption. The goal of this study is to better constrain the degassing and mobility of trace elements in gaseous emissions. Trace element volatility at Hekla is quantified by means of enrichment factors (EF) relative to Be. Well-known volatile trace elements (e.g., transition metals, heavy metals, and metalloids) are considerably enriched in the volcanic plume of Hekla. Their abundances are governed by the primary magmatic degassing of sulfate and/or halide compounds, which are gaseous at magmatic temperature. Their volatility is, however, slightly lower than in basaltic systems, most likely because of the lower magma temperature and higher magma viscosity at Hekla. More surprisingly, refractory elements (e.g., REE, Th, Ba, and Y) are also significantly enriched in the eruptive plume of Hekla where their apparent volatility is two orders of magnitude higher than in mafic systems. In addition, REE patterns normalized to the Hekla 2000 lava composition show a significant enrichment of HREE over LREE, suggesting the presence of REE fluorides in the volcanic plume. Such enrichments in the most refractory elements and REE fractionation are difficult to reconcile with primary degassing processes, since REE fluorides are not gaseous at magma temperature. REE enrichments at Hekla could be attributed to incongruent dissolution of tephra grains at low temperature by F-rich volcanic gases and aerosols within the eruptive plume. This view is supported by both leaching experiments performed on Hekla tephra and thermodynamic considerations on REE mobility in hydrothermal fluids and modeling of glass dissolution in F-rich aqueous solutions. Tephra dissolution may also explain the observed enrichments in other refractory elements (e.g., Th, Y, and Ba) and could contribute to the degassing mass balance of some volatile trace elements, provided they are mobile in F-rich fluids. It thus appears that both primary magmatic degassing and secondary tephra dissolution processes govern the chemistry of eruptive plumes released during explosive eruptions.

V838 Mon: light echo evolution and distance estimate

Following its 2002 February eruption, V838 Mon developed a light echo that continues to expand and evolve as light from the outburst scatters off progressively more distant circumstellar and/or interstellar material. Multifilter images of the light echo, obtained with the South African Astronomical Observatory (SAAO) 1.0-m telescope between 2002 May and 2004 December, are analysed and made available electronically. The expansion of the light echo is measured from the images and the data compared with models for scattering by a thin sheet and a thin shell of dust. From these model results we infer that the dust is probably in the form of a thin sheet distant from the star, suggesting that the material is of interstellar origin, rather than being from earlier stages in the evolution of the star. Although the fit is uncertain, we derive a stellar distance of ∼9 kpc and a star–dust distance of ∼5 pc, in good agreement with recent results reported from other methods. We also present JHKL and Cousins UBVRI photometry obtained at the SAAO during the post-outburst second, third and fourth observing seasons of the star. These data show complex infrared colour behaviour while V838 Mon is slowly brightening in the optical.

External and Internal Reconnection in Two Filament‐Carrying Magnetic Cavity Solar Eruptions

We observe two near-limb solar filament eruptions, one of 2000 February 26 and the other of 2002 January 4. For both we use 195 Angstroms, Fe XII images from the Extreme-Ultraviolet Imaging Telescope (EIT) and magnetograms from the Michelson Doppler Imager (MDI), both of which are on the Solar arid Heliospheric Observatory (SOHO). For the earlier event we also use soft X-ray telescope (SXT), hard X-ray telescope (HXT), and Bragg Crystal Spectrometer (BCS) data from the Yohkoh satellite, and hard X-ray data from the BATSE experiment on the Compton Gamma Ray Observation, (CGRO). Both events occur in quadrupolar magnetic regions, and both have coronal features that we infer belong to the same magnetic cavity structures as the filaments. In both cases, the cavity and filament first rise slowly at approximately 10 kilometers per second prior to eruption and then accelerate to approximately 100 kilometers per second during the eruption, although the slow-rise movement for the higher altitude cavity elements is clearer in the later event. We estimate that both filaments and both cavities contain masses of approximately 10(exp 14)-10(exp 15) and approximately 10(exp 15)-10(exp 16)g, respectively. We consider whether two specific magnetic reconnection-based models for eruption onset, the tether cutting and the breakout models, are consistent with our observations. In the earlier event, soft X-rays from SXT show an intensity increase during the 12 minute interval over which fast eruption begins, which is consistent with tether-cutting-model predictions. Substantial hard X-rays, however, do not occur until after fast eruption is underway, and so this is a constraint the tether-cutting model must satisfy. During the same 12 minute interval over which fast eruption begins, there are brightenings and topological changes in the corona indicative of high-altitude reconnection early in the eruption, and this is consistent with breakout predictions. In both eruptions, the state of the overlying loops at the time of onset of the fast-rise phase of the corresponding filament can be compared with expectations from the breakout model, thereby setting constraints that the breakout model must meet. Our findings are consistent with both runaway tether-cutting-type reconnection and fast breakout-type reconnection, occurring early in the fast phase of the February eruption and with both types of reconnection being important in unleashing the explosion, but we are not able to say which, if either, type of reconnection actually triggered the fast phase. In any case, we have found specific constraints that either model, or any other model, must satisfy if correct.

Integrated satellite observations of the 2001 eruption of Mt. Cleveland, Alaska

Satellite data were the primary source of information for the eruption of Mt. Cleveland, Alaska on 19 February, and 11 and 19 March 2001. Multiple data sets were used pre-, syn- and post-eruption to mitigate the hazard and determine an eruption chronology. The 19 February eruption was the largest of the three, resulting in a volcanic cloud that formed an arc over 1000 km long, moved to the NE across Alaska and was tracked using satellite data over more than a 50-h period. The volcanic cloud was “concurrently” detected on the GOES, AVHRR and MODIS data at various times and their respective signals compared. All three sensors detected a cloud that had a very similar shape and position but there were differences in their areal extent and internal structural detail. GOES data showed the largest volcanic cloud in terms of area, probably due to its oblique geometry. MODIS bands 31 and 32, which are comparable to GOES and AVHRR thermal infrared wavelengths, were the least effective single channels at detecting the volcanic cloud of those investigated (MODIS bands 28, 29, 31 and 32). MODIS bands 28 and 29 detected the largest volcanic clouds that could easily be distinguished from weather clouds. Of the split-window data, MODIS bands 29 minus band 32 detected the largest cloud, but the band 31 minus band 32 data showed the volcanic cloud with the most internal structural detail. The Puff tracking model accurately tracked the movement, and predicted the extent and shape of this complex cloud even into areas beyond satellite detection. Numerous thermal anomalies were also observed during the eruption on the twice-daily AVHRR data and the high spatial-resolution Landsat data. The high-resolution Radarsat data showed that the AVHRR thermal anomalies were due to lava and debris flow features and a newly formed fan along the west coast of the island. Field observations and images from a hand-held Forward Looking Infrared Radiometer (FLIR) showed that the flow features were ′a′a lava, debris flows and a warm debris fan along the west coast. Real-time satellite data were the primary tool used to monitor the eruption, track changes and to mitigate hazards. High-resolution data, even though coverage is infrequent, were critical in helping to identify volcanic processes and to compile an eruption chronology.

Infrasonic Observations of the Hekla Eruption of February 26, 2000

INTRODUCTION On February 26-27, 2000 infrasonic signals associated with the eruption of the Hekla Volcano, Iceland, were recorded by the Swedish infrasound network. This network is operated by the Swedish Institute of Space Physics and consists of 4 stations located in Kiruna, Jamton and Lycksele in Northern Sweden and Uppsala in Central Sweden. Each station consists of an array of 3 modified Lidstrommicrophones (see Appendix 1) with a 7 Hz low-pass filter, so that the effective frequency range is 0.5 6 Hz. A sampling rate of 18 Hz is used at all stations. The microphones at each array are located in the corners of a right angle triangle, where the perpendicular sides are 75 m long and oriented East-West and North-South. Shelters reduce wind noise at each array element. The Kiruna and Lycksele array data may be accessed at http://callisto.space.umu.se. Geographical coordinates for the stations are given in Table I.

Mayon volcano, Philippines: change of monitoring strategy after microgravity and GPS measurements from 1992 to 1996

Mayon volcano is part of the Bicol volcanic chain on the island Luzon, Philippines. During this century there were ten activity periods distributed almost regularly. Because of the density of population (about one million people living in the vicinity of the volcano) three seismological observatories are in operation.Measurements of gravity changes started in 1992, just before the eruption of February/March 1993. Two profiles at the slope were established, connected to a regional network around the volcano. In order to enable the determination of mass changes between the campaigns the height control was provided by parallel GPS measurements. In all, the network consists of 26 points which were remeasured with three gravimetres at least three times within one campaign.During five campaigns within 4 years the differential GPS gives no significant changes of the elevation (within ±4cm). Nevertheless, the gravity increased significantly by up to 1500nm/s2 (equivalent to 150μGal).As no significant change of elevation is observed (GPS), no extended shallow magma chamber system below the volcano can be proved. This is in accordance with geochemical results indicating a rather undifferentiated magma. The youngest lava which is of interest for the eruption dynamics belongs to the medium-K basaltic andesite field of the K2O vs SiO2 diagram.A rather qualitative check of groundwater level changes reveals that these cannot be the sources for the observed gravity changes. Thus, the increase of gravity after the eruption of February 1993 can be explained by a mass redistribution in the volcanic vent from above the level of the gravity points to below.Practical conclusions of these results lead to changes in the monitoring strategy: Deformation measurements did not reveal any volcanic activities; at least for the eruption of 1993 no significant deformation was observed. Gravity could be an indicator for long-term changes. Thus, repeated gravity measurements/GPS at selected points could be used in parallel to seismic monitoring to detect slow mass movements prior to changes in seismicity.

Statistical forecasting of repetitious dome failures during the waning eruption of Redoubt Volcano, Alaska, February–April 1990

The waning phase of the 1989–1990 eruption of Redoubt Volcano in the Cook Inlet region of south-central Alaska comprised a quasi-regular pattern of repetitious dome growth and destruction that lasted from February 15 to late April 1990. The dome failures produced ash plumes hazardous to airline traffic. In response to this hazard, the Alaska Volcano Observatory sought to forecast these ash-producing events using two approaches. One approach built on early successes in issuing warnings before major eruptions on December 14, 1989 and January 2, 1990. These warnings were based largely on changes in seismic activity related to the occurrence of precursory swarms of long-period seismic events. The search for precursory swarms of long-period seismicity was continued through the waning phase of the eruption and led to warnings before tephra eruptions on March 23 and April 6. The observed regularity of dome failures after February 15 suggested that a statistical forecasting method based on a constant-rate failure model might also be successful. The first statistical forecast was issued on March 16 after seven events had occurred, at an average interval of 4.5 days. At this time, the interval between dome failures abruptly lengthened. Accordingly, the forecast was unsuccessful and further forecasting was suspended until the regularity of subsequent failures could be confirmed. Statistical forecasting resumed on April 12, after four dome failure episodes separated by an average of 7.8 days. One dome failure (April 15) was successfully forecast using a 70% confidence window, and a second event (April 21) was narrowly missed before the end of the activity. The cessation of dome failures after April 21 resulted in a concluding false alarm. Although forecasting success during the eruption was limited, retrospective analysis shows that early and consistent application of the statistical method using a constant-rate failure model and a 90% confidence window could have yielded five successful forecasts and two false alarms; no events would have been missed. On closer examination, the intervals between successive dome failures are not uniform but tend to increase with time. This increase attests to the continuous, slowly decreasing supply of magma to the surface vent during the waning phase of the eruption. The domes formed in a precarious position in a breach in the summit crater rim where they were susceptible to gravitational collapse. The instability of the February 15–April 21 domes relative to the earlier domes is attributed to reaming the lip of the vent by a laterally directed explosion during the major dome-destroying eruption of February 15, a process which would leave a less secure foundation for subsequent domes.

P40 ホワイト島火山 1992 年 2 月 20 日の噴火に伴う地震

P40 ホワイト島火山 1992 年 2 月 20 日の噴火に伴う地震

The 1974 etna eruption: Multispectral analysis of skylab images reveals the vegetation canopy as a likely transducer of pre-eruptive volcanic emissions

On the Skylab images taken over Mt. Etna in September, 1973, an area with a reduced near-infrared reflectivity was observed in the zone where five months later the lateral eruption of February 1974 took place. This fact suggested to the authors the working hypothesis that the vegetation was influenced by latent volcanic phenomena. Moreover the intensification of linear features across the same area led to the development of a new point of view in which the vegetation is perceived as a volcanologic transducer. Ground investigations and thermal-infrared and multispectral surveys performed in July 1974 neither confirmed nor contradicted the first part of the assumption because subsequent paroxysmal phenomena modified the area investigated. The multispectral analysis on the other hand gave a greater emphasis to the correlation between the linear features and the distribution of plants. A more detailed study of this relationship is suggested.

The 1959 February Eruption of Volcano Kirishima

The 1959 February Eruption of Volcano Kirishima

Vesuvian Eruption of February 4, 1886

THE rent that was formed on May 2, 1885, in the upper part of the great cone (NATURE, vol. xxxii. p. 55) gave issue to lava until December 25. A small quantity again issued between January 2 and January 5, 1886, after which no more made its appearance till this new outburst.In consequence of the rise of level of the magma in the chimney, the cone of eruption has grown very much during the last month.

On the Lavas of Hekla, and on the Sublimations Produced During the Eruption of February 27, 1878

On the Lavas of Hekla, and on the Sublimations Produced During the Eruption of February 27, 1878

ON AN ASCENT OF MOUNT HEKLA, AND ON THE ERUPTION OF FEBRUARY 27, 1878

ON February 27 last severe earthquakes were felt throughout the south-west portion of Iceland, particularly in the districts of Land, Rangarollir, Hreppa, and Fljotschlith, which are situated immediately to the south and south-west of Mount Hekla. Between 8 and 9 P.M. an intense illumination of the sky, at first believed to be actual fire, was seen to the south-east. This was found to be due to the reflection by clouds of the light emitted by molten lava within a subsidiary crater, or bocca del fuoco, as the Italians would call it, of Hekla. On the following day dense columns of smoke ascended from the crater, and quantities of volcanic ashes fell in the districts of Hreppa and Biskupstundur. The light was seen at Reykjavik, nearly seventy miles distant, and there appeared to be two vents of fire.