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1.
The year 2015 marks the bicentenary of the largest eruption in recent historic times: the 10–11 April 1815 eruption of Mount Tambora, Indonesia. Two hundred years after the eruption, an incomplete or inaccurate record of large eruptions over the past millennia, and uncertainties in determining the true sizes of eruptions, hamper our ability to predict when the next eruption of this scale may occur. Such events would have catastrophic effects locally and, possibly, world‐wide. The problem is compounded by a lack of detailed knowledge of how and over what timescales large magma reservoirs that feed such eruptions grow and assemble, and of the surface manifestations of these processes recorded through geophysical or geochemical monitoring techniques. 相似文献
2.
The 2011 eruption of Nabro volcano, Eritrea, produced one of the largest volcanic sulphur inputs to the atmosphere since the 1991 eruption of Mt. Pinatubo, yet has received comparatively little scientific attention. Nabro forms part of an off-axis alignment, broadly perpendicular to the Afar Rift, and has a history of large-magnitude explosive silicic eruptions, as well as smaller more mafic ones. Here, we present and analyse extensive petrological data obtained from samples of trachybasaltic tephra erupted during the 2011 eruption to assess the pre-eruptive magma storage system and explain the large sulphur emission. We show that the eruption involved two texturally distinct batches of magma, one of which was more primitive and richer in sulphur than the other, which was higher in water (up to 2.5 wt%). Modelling of the degassing and crystallisation histories demonstrates that the more primitive magma rose rapidly from depth and experienced degassing crystallisation, while the other experienced isobaric cooling in the crust at around 5 km depth. Interaction between the two batches occurred shortly before the eruption. The eruption itself was likely triggered by recharge-induced destabilisation of vertically extensive mush zone under the volcano. This could potentially account for the large volume of sulphur released. Some of the melt inclusions are volatile undersaturated, and suggest that the original water content of the magma was around 1.3 wt%, which is relatively high for an intraplate setting, but consistent with seismic studies of the Afar plume. This eruption was smaller than some geological eruptions at Nabro, but provides important insights into the plumbing systems and dynamics of off-axis volcanoes in Afar. 相似文献
3.
强火山活动是气候变化的重要自然驱动因素,可导致中国降水出现年际或年代际变化,甚至极端的旱涝现象。探究位于中国邻域的印度尼西亚—菲律宾一带的强火山喷发与中国旱涝分布格局的关系,有助于阐释中国旱涝发生的时空规律及机制,为预测未来火山爆发可能导致的降水异常提供借鉴。本文基于1500—2000年期间世界强火山活动和中国旱涝资料,运用时序叠加分析的方法辨识了印度尼西亚—菲律宾一带的强火山喷发后中国旱涝在年际尺度上的时空变化特征,并对1815年Tambora火山喷发进行案例分析。结果表明印度尼西亚—菲律宾一带的强火山喷发对中国的旱涝格局有一定的影响:强火山喷发后第0年至第2年,中国中东部各站点的整体变化为偏涝;在第3年,整体出现了偏旱的转变,且变化幅度相比其他年份较大;就地区而言,喷发后华北、华南地区分别出现了由旱转涝、由涝转旱的变化,并且这些变化大概持续了2~3年,随后2个区域均恢复了喷发前的旱涝趋势;印度尼西亚1815年Tambora火山喷发后0~3年,中国以涝情为主,但发生涝情的区域逐年在发生变化。 相似文献
4.
The major element chemical compositions of lava from four eruptionson the east rift zone of Kilauea between August 1968 and October1971 reflect three petrologic processes:
- Production of chemically distinct batches of magma in the mantle.
- Separation of olivine, augite, and plagioclase from liquidduringflow in the rift-zone conduits.
- Mixing of differentmagmas during ascent to the surface.
5.
Eruptions in the subglacial Katla caldera, South Iceland, release catastrophic jokulhlaups (meltwater floods). The ice surface
topography divides the caldera into three drainage sectors (Ko, So and En sectors) that drain onto Myrdalssandur, Solheimasandur
and Markarfljot plains, respectively. In historical times, floods from the Ko sector have been dominant, with only two recorded
So events. Geological records indicate that floods from the En sector occur every 500–800 years. A probabilistic model for
an eruption is formulated in general terms by a stochastic parameter that simulates a series giving the time interval in years
between two consecutive events. The model also contains a Markovian matrix that controls the location of the event and thereby
what watercourse is hit by the flood. A record of Katla eruptions since the 8th and the 9th century a.d., and geological information of volcanogenic floods towards the west over the last 8,000 years is used to calibrate the model.
The model is then used to find the probabilities for floods from the three sectors: Ko, So and En. The simulations predict
that the most probable eruption interval for the En sector and the So sector is several times smaller than the average time
interval, implying infrequent periods of high activity in these sectors. A correlation is found between the magnitude of eruptions
and the following time intervals. Using the statistical approach and considering this magnitude–time interval correlation,
the probability of an eruption in Katla volcano is considered to be 20% within the next 10 years. This compares to a probability
of 93% if only a simple average is considered. These probabilities do not take account of long-term eruption precursors and
should therefore be regarded as minimum values. 相似文献
6.
The main goal of this investigation is estimating volume of volatile emission, atmospheric and climatic impact of the Kurile
Lake caldera-forming eruption, one of the Earth’s largest Holocene explosive eruptions. The volatile content of magma before
the eruption was estimated by comparing H2O, S, Cl and F contents in natural quenched glassy melt inclusions trapped by plagioclase phenocrysts. The volatile content
of igneous rocks after eruption was estimated by comparing concentrations of degassed matrix glasses. As a result of KO-eruption
not more than (3.7–4.2) × 1012 kg of water, (4.3–4.9) × 1010 kg of chlorine, (8.6–9.8) × 109 kg of fluorine and (2.6–2.9) × 1010 kg of sulphur were injected into the atmosphere. This eruption had to produce an important climatic impact. 相似文献
7.
Eruption records in the terrestrial stratigraphy are often incomplete due to erosion after tephra deposition, limited exposure and lack of precise dating owing to discontinuity of strata. A lake system and sequence adjacent to active volcanoes can record various volcanic events such as explosive eruptions and subaqueous density flows being extensions of eruption triggered and secondary triggered lahars. A lacustrine environment can constrain precise ages of such events because of constant and continuous background sedimentation. A total of 71 subaqueous density flow deposits in a 28 m long core from Lake Inawashiro‐ko reveals missing terrestrial volcanic activity at Adatara and Bandai volcanoes during the past 50 kyr. Sedimentary facies, colour, grain size, petrography, clay mineralogy, micro X‐ray fluorescence analysis and chemistry of included glass shards characterize the flow event deposits and clarify their origin: (i) clay‐rich grey hyperpycnites, extended from subaerial cohesive lahars at Adatara volcano, with sulphide/sulphate minerals and high sulphur content which point to a source from hydrothermally altered material ejected by phreatic eruptions; and (ii) clay‐rich brown density flow deposits, induced by magmatic hydrothermal eruptions and associated edifice collapse at Bandai volcano, with the common presence of fresh juvenile glass shards and low‐grade hydrothermally altered minerals; whereas (iii) non‐volcanic turbidites are limited to the oldest large slope failure and the 2011 Tohoku‐oki earthquake events. The high‐resolution chronology of volcanic activity during the last 50 kyr expressed by lacustrine event deposits shows that phreatic eruption frequency at Adatara has roughly tripled and explosive eruptions at Bandai have increased by ca 50%. These results challenge hikers, ski‐fields and downstream communities to re‐evaluate the increased volcanic risks from more frequent eruptions and far‐reaching lahars, and demonstrate the utility of lahar and lacustrine volcanic density flow deposits to unravel missing terrestrial eruption records, otherwise the recurrence rate may be underestimated at many volcanoes. 相似文献
8.
Although a relationship between the occurrence of large earthquakes and the eruptions of close mud volcanoes is well known, several uncertainties remain on understanding the triggering mechanisms. In the present study, we evaluate both the static and dynamic strains induced by earthquakes in the substratum of mud volcanoes. We studied the effects of two earthquakes of M w 6.18 and 6.08 occurred in the Caspian Sea on 25 November 2000 close to Baku city, Azerbaijan. A total of 33 eruptions occurred at 24 mud volcanoes within a maximum distance of 108 km from the epicentres in the 5 years following the earthquakes. The overall eruption rate in the studied area of the 50 years before the 2000 earthquakes was 1.24 that is much smaller than the eruption rate of 6.6 of the 5 years following these earthquakes. The largest number of eruptions occurred within 2 years from the earthquakes with the highest frequency within 6 months. Our calculated earthquake-induced static effects show that crustal dilatation might have triggered only seven eruptions at a maximum distance of about 60 km from the epicentres and within 3 years. Based on our data, dynamic rather than static strain is likely to have been the dominating “promoting” factor because it affected all the studied unrest volcanoes and its magnitude was much larger. 相似文献
9.
R. K. R. Vupputuri 《Natural Hazards》1984,5(1):1-16
A coupled one-dimensional radiative-convective-photochemical diffusion model, which takes into account the influence of ocean inertia on global radiative perturbations is used to investigate the possible climatic and other atmospheric effects of a major volcanic eruption, thought to be similar in magnitude to that of the Tambora eruption, Indonesia, which took place in 1815. A volcanic cloud was introduced in the model stratosphere between 20–25 km and the global average peak aerosol optical thickness was assumed to be 0.25. Both the aerosol optical thickness and aerosol composition, which determine the optical properties, were allowed to vary in the model atmosphere during the life cycle of the volcanic cloud. The results indicate that the global average surface temperature decreases steadily from the date of eruption (7–12 April 1815) with maximum cooling of 1° K occurring in the spring of 1816. The calculations also show significant warming of the stratosphere, with temperature increasing up to 15° K at 25 km in less than six months after the date of eruption. The important effects of the Tambora eruption on stratospheric ozone and UV-B radiation at the surface are also mentioned. 相似文献
10.
GUDRÚN LARSEN Bryndís G. Róbertsdóttir Bergrún A. Óladóttir JÓN EIRÍKSSON 《第四纪科学杂志》2020,35(1-2):143-154
Hekla volcano is a major producer of large, widespread silicic tephras. About 3000 years ago, the dominant eruption mode shifted from infrequent large (>1 km3) to more frequent moderate (<1 km3) eruptions. In the following two millennia ≥20 explosive silicic-to-intermediate eruptions occurred, and six or more basaltic. Three categories can be identified with dacite/andesite to basaltic andesite in the oldest eruptions through basaltic andesite to basalt in the youngest eruptions. Ten tephra layers of the first category have distinct field characteristics: a pale lower unit and a dark upper unit (two coloured or TC-layers). Colour separation is sharp indicating a stratified magma chamber origin. The lower unit is dominantly andesitic (61–63% SiO2), while the upper unit is basaltic andesite (53–57% SiO2). Volumes of the eight largest TC-layers range from 0.2 to 0.7 km3 as freshly fallen. Radiocarbon and soil accumulation rate dates constrain the TC-layers to between 3000 and 2200 years ago. Two of these (~2890 and ~2920 b2k) are likely to occur overseas. Low SiO2 in the last erupted tephra of the TC-layers is comparable to that of historical Hekla lavas, implying a final effusive phase. The Hekla edifice may, consequently, be younger than 3000 years. 相似文献
11.
Mount Etna is an open conduit volcano, characterised by persistent activity, consisting of degassing and explosive phenomena
at summit craters, frequent flank eruptions, and more rarely, eccentric eruptions. All eruption typologies can give rise to
lava flows, which represent the greatest hazard by the volcano to the inhabited areas. Historical documents and scientific
papers related to the 20th century effusive activity have been examined in detail, and volcanological parameters have been
compiled in a database. The cumulative curve of emitted lava volume highlights the presence of two main eruptive periods:
(a) the 1900–1971 interval, characterised by a moderate slope of the curve, amounting to 436 × 106 m3 of lava with average effusion rate of 0.2 m3/s and (b) the 1971–1999 period, in which a significant increase in eruption frequency is associated with a large issued lava
volume (767 × 106 m3) and a higher effusion rate (0.8 m3/s). The collected data have been plotted to highlight different eruptive behaviour as a function of eruptive periods and
summit vs. flank eruptions. The latter have been further subdivided into two categories: eruptions characterised by high effusion
rates and short duration, and eruptions dominated by low effusion rate, long duration and larger volume of erupted lava. Circular
zones around the summit area have been drawn for summit eruptions based on the maximum lava flow length; flank eruptions have
been considered by taking into account the eruptive fracture elevation and combining them with lava flow lengths of 4 and
6 km. This work highlights that the greatest lava flow hazard at Etna is on the south and east sectors of the volcano. This
should be properly considered in future land-use planning by local authorities. 相似文献
12.
Kilauea Volcano has erupted lava from its summit caldera andfrom two rift zones that extend from the summit towards theeast and south-west. Lavas erupted from the summit of the volcanodiffer from each other principally in their content of olivineand define lines of ‘olivine control’ on magnesiavariation diagrams. Lavas erupted on the rift zones may be similarin composition to the summit lavas or may be differentiatedby processes that involve minerals other than olivine. All ofthe differentiated lavas have less than 6·8 per centMgO and plot off the extension of olivine control lines forthe summit lavas. Prehistoric vents (before A.D. 1750) fromwhich differentiated lavas have been erupted are found on theeast rift zone and in the western Koae fault zone adjacent tothe south-west rift zone; historic vents for differentiatedlavas are confined to the east rift zone. Twenty-one new analysesare presented for several of the east rift differentiates andfor the newly discovered differentiates adjacent to the south-westrift zone. The differentiates have MgO as low as 3·9per cent and SiO2 as high as 56 per cent; both extremes arefound in the prehistoric lavas adjacent to the south-west rift. Detailed petrochemical studies suggest the following conclusions:
- Thechemical composition of magma erupted at Kilauea summitvarieswith the date of eruption. Lavas erupted before 1750,duringthe eighteenth and nineteenth centuries, and in the twentiethcentury form groups that can be distinguished chemically. Ona lesser scale, each Kilauea summit eruption in the twentiethcentury has a chemistry that is distinctive with respect tothe chemistry of every other summit eruption.
- During lateprehistoric time pockets of differentiated magmawere formedwithin the rift zones by separation of the liquidremainingafter partial crystallization of bodies of summitmagma. Thisprocess presumably is still going on within theeast rift zone,but the more recently separated liquids havenot yet been eruptedto the surface. The relative time at whichthese differentiatedmagmas were produced can be estimated fromcalculations basedon their chemical compositions, which showthat the differentiatescould lie on the liquid line of descentfor Kilauea summit magmaof prehistoric composition but noton any liquid line of descentfor younger summit magmas.
- Lava from some eruptions, notablythe early part of the 1955eruption on the lower east rift,has the composition of theliquid fraction as it is generatedwithin the rift. Lava compositionsof other eruptions, includingthose of the later lavas of 1955,are best explained by mixingof magma supplied from a centralreservoir beneath Kilauea summitwith the differentiated liquidin the rift. Lava from each summiteruption is unique chemically,so it is possible to recognizeits presence or absence as componentsof mixing in such mixedlavas. It appears that summit magmaof composition characteristicof the 1952 and 1961 Halemaumaueruptions contributed to thecomposition of the mixed lavasproduced in the latter part ofthe 1955 eruption. Summit magmaof 1961 composition is alonesufficient to explain the compositionof mixed lavas eruptedin 1960 and 1961. In rift lavas eruptedfrom 1962 to 1965, thecomposition of lava erupted in Halemaumauin 1967, in additionto the 1961 composition, is a componentof mixing, and it isthe dominant summit component in the compositionof the two1965 eruptions. The proportion of summit magma todifferentiatedmagma needed to explain the composition of lavaserupted onthe upper east rift increases from 1961 to 1965;this increaseindicates that the differentiated magma was beingdiluted andused up by repeated flooding of this part of therift zone bymagma supplied from the central reservoir.
- The fact that componentsof ‘summit composition’appear in rift eruptionsbefore they appear undiluted in Halemaumausuggests that thecentral reservoir is vertically zoned. Rifteruptions are fedfrom lower levels where younger magma is available,and summiteruptions are fed from the relatively older magmaabove. Thechemical distinction between lava of successive summiteruptionsimplies that significant convective mixing of magmadoes nottake place throughout the central reservoir.
- The unique anduniform composition of lava of each successivesummit eruptionalso suggests that summit eruptions end whenall of the magmaof one composition has been erupted. The magmaerupted fromthe upper levels of the reservoir during one cycleis continuallyreplaced from below by younger magma of differentcomposition.In order for eruption to be renewed in Halemaumau,new magmafrom the mantle must be held in storage at intermediatelevelsbefore it attains an ‘eruptive state’.
- The hypothesispresented in 2–4 above permits qualitativepredictionsconcerning future lava compositions. The compositionof thenext lava to be erupted in Halemaumau is expected tobe distinctfrom that of the 1967 eruption, and this compositionwill presumablybe identified in rift eruptions occurring between1967 and thetime of its appearance in Halemaumau.
- Differentiates of prehistoricage also were apparently formedin the same way as those ofhistoric age, but the mixing cannotbe described quantitativelybecause of poor control on the stratigraphyand the compositionsof erupted lavas. One lava in the Koaegroup, that from YellowCone, appears to be a mixture of a picriticmagma (12 per centMgO) with a differentiated liquid with lessthan 2·5per cent MgO and nearly 60 per cent SiO2.
13.
The behavior of chlorine and sulfur during differentiation of the Mt. Somma-Vesuvius magmatic system 总被引：4，自引：0，他引：4
Summary Reheated silicate melt inclusions in volcanic rock samples from Mt. Somma-Vesuvius, Italy, have been analyzed for 29 constituents
including H2O, S, Cl, F, B, and P2O5. This composite volcano consists of the older Mt. Somma caldera, formed between 14 and 3.55 ka before present, and the younger
Vesuvius cone. The melt inclusion compositions provide important constraints on pre-eruptive magma geochemistry, identify
relationships that relate to eruption behavior and magma evolution, and provide extensive evidence for magmatic fluid exsolution
well before eruption.
The melt inclusion data have been categorized by groups that reflect magma compositions, age, and style of eruptions. The
data show distinct differences in composition for eruptive products older than 14.0 ka (pre-caldera rocks) versus eruptive
products younger than 3.55 ka. Moreover, pre-caldera eruptions were associated with magmas relatively enriched in SiO2, whereas eruptions younger than 3.55 ka (i.e., the syn- and post-caldera magmas which generated the Somma caldera and the
Vesuvius cone) were derived from magmas comparatively enriched in S, Cl, CaO, MgO, P2O5, F, and many lithophile trace elements.
Melt inclusion data indicate that eruptive behavior at Vesuvius correlates with pre-eruptive volatile enrichments. Most magmas
associated with explosive plinian and subplinian events younger than 3.55 ka contained more H2O, contained significantly more S, and exhibited higher (S/Cl) ratios than syn- and post-caldera magmas which erupted during
relatively passive interplinian volcanic phenomena.
Received January 10, 2000 Revised version accepted July 17, 2000 相似文献
14.
Reconstruction of an Evolving Magma Chamber beneath Usu Volcano since the 1663 Eruption 总被引：4，自引：3，他引：1
Usu volcano, located in northern Japan, has erupted seven timessince AD 1663. Before these seven eruptions, the volcano hada long repose period ( 5000 yr). The 1663 eruption was thefirstand by far the largest among the seven, producing nearlyaphyric rhyolitic pumice. Small mafic inclusions (‘micro-clots’J,consisting of glass, quenched crystals and abundant vesiclesoccur in the pumice. On the basis of petrological studies ofthe microclots, it is concluded that these are quenched meltsof a mafic magma injected into the rhyolite. The products ofthe 1769 eruption (and those of the following five eruptions)were dacites with abundant (10–15 vol %) microphenocrysts.According to crystal size distribution (CSD) analysis, the newmicrophenocrysts appear to have crystallized at a considerablyhigher cooling rate ( 300 times) than the phenocrysts in the1663 eruptive products. The contrasting petrologic featuresof the aphyric rhyolite and the following microphenocryst-richdacites can be explained by mixing and rapid cooling of a maficmagma injected during the 1663 eruption. We estimate the sizeof the magma chamber beneath Usu volcano just after the 1663eruption, using numerical calculations for a cooling magma chamber.If the magma chamber was sill-like, its thickness is estimatedto have been several hundreds of meters. KEY WORDS: Usu volcano; Japan; magma chamber evolution
*Corresponding author. Present address: Geomechanics, Earthquake Research Institute, The University of Tokyo, I-I-I Yayoi, Bunkyo-ku, Tokyo 113, Japan 相似文献
15.
A detailed 90,000-year tephrostratigraphic framework of Aso Volcano, southwestern Japan, has been constructed to understand the post-caldera eruptive history of the volcano. Post-caldera central cones were initiated soon after the last caldera-forming pyroclastic-flow eruption (90 ka), and have produced voluminous tephra and lava flows. The tephrostratigraphic sequence preserved above the caldera-forming stage deposits reaches a total thickness of 100 m near the eastern caldera rim. The sequence is composed mainly of mafic scoria-fall and ash-fall deposits but 36 silicic pumice-fall deposits are very useful key beds for correlation of the stratigraphic sequence. Explosive, silicic pumice-fall deposits that fell far beyond the caldera have occurred at intervals of about 2500 years in the post-caldera activity. Three pumice-fall deposits could be correlated with lava flows or an edifice in the western part of the central cones, although the other silicic tephra beds were erupted at unknown vents, which are probably buried by the younger products from the present central cones. Most of silicic eruptions produced deposits smaller than 0.1 km3, but bulk volumes of two silicic eruptions producing the Nojiri pumice (84 ka) and Kusasenrigahama pumice (Kpfa; 30 ka) were on the order of 1 km3 (VEI 5). The largest pyroclastic eruption occurred at the Kusasenrigahama crater about 30 ka. This catastrophic eruption began with a dacitic lava flow and thereafter produced Kpfa (2.2 km3). Total tephra volume in the past 90,000 years is estimated at about 18.1 km3 (dense rock equivalent: DRE), whereas total volume for edifices of the post-caldera central cones is calculated at about 112 km3, which is six times greater than the former. Therefore, the average magma discharge rate during the post-caldera stage of Aso Volcano is estimated at about 1.5 km3/ky, which is similar to the rates of other Quaternary volcanoes in Japan. 相似文献
16.
Andrew Tupper Christiane Textor Michael Herzog Hans-F. Graf Michael S. Richards 《Natural Hazards》2009,51(2):375-401
A critical factor in successfully monitoring and forecasting volcanic ash dispersion for aviation safety is the height reached by eruption clouds, which is affected by environmental factors, such as wind shear and atmospheric instability. Following earlier work using the Active Tracer High Resolution Atmospheric Model for strong Plinian eruptions, this study considered a range of eruption strengths in different atmospheres. The results suggest that relatively weak volcanic eruptions in the moist tropics can trigger deep convection that transports volcanic material to 15–20 km. For the same volcanic strength there can be ~9 km difference between eruption heights in moist tropical and dry subpolar environments (a larger height difference than previously suggested), which appears consistent with observations. These results suggest that eruption intensity should not be estimated from eruption height alone for tropospheric eruptions and also that the average height of volcanic eruptions may increase if the tropical atmospheric belt widens in a changing climate. Ash aggregation is promoted by hydrometeors (particularly liquid water), so the smaller modelled eruptions in moist atmospheres, which have a relatively small ash content for their height and water content, result in a relatively small proportion of fine ash in the dispersing cloud when compared to a dry atmosphere. This in turn makes the ash clouds much more difficult to detect using remote sensing than those in dry atmospheres. Overall, a weak eruption in the tropics is more likely to produce a plume above cruising levels for civil aviation, harder to detect and track, but with a lower concentration of fine ash than a mid-latitude or polar equivalent. There is currently no defined ‘acceptable’ concentration of ash for aircraft, but as these results suggest low-grade encounters in the tropics from undetected clouds are likely, it would be desirable to explore that issue. 相似文献
17.
Levin B. W. Rybin A. V. Vasilenko N. F. Prytkov A. S. Chibisova M. V. Kogan M. G. Steblov G. M. Frolov D. I. 《Doklady Earth Sciences》2010,435(1):1507-1510
In June 2009, one of the greatest eruptions of the Sarychev Peak volcano in Matua Island (48°06′ N, 153°12′ E) for the recent
historical period occurred. With the help of satellite sounding methods, the first signs of volcanic activity were recorded
and all the stages of the explosive eruption were traced. During the expeditionary investigations in the active volcano, unique
data on the character of the eruption were obtained. The volume of erupted material was 0.4 cubic km, which lead to an increased
area of Matua Island by 1.4 square km. The GPS observation station set at the distance of 7 km from the volcano recorded the
rapid displacement of the Earths’s surface during the first two days of the active phase of eruption. This eruption of the
Sarychev Peak volcano occurred 2.5 years after the catastrophic Simushir earthquakes in the period of intensive relaxation
of stresses in the middle of the central part of the Kurile island arc. 相似文献
18.
R. K. R. Vupputuri 《Natural Hazards》1992,5(1):1-16
A coupled one-dimensional radiative-convective-photochemical diffusion model, which takes into account the influence of ocean inertia on global radiative perturbations is used to investigate the possible climatic and other atmospheric effects of a major volcanic eruption, thought to be similar in magnitude to that of the Tambora eruption, Indonesia, which took place in 1815. A volcanic cloud was introduced in the model stratosphere between 20–25 km and the global average peak aerosol optical thickness was assumed to be 0.25. Both the aerosol optical thickness and aerosol composition, which determine the optical properties, were allowed to vary in the model atmosphere during the life cycle of the volcanic cloud. The results indicate that the global average surface temperature decreases steadily from the date of eruption (7–12 April 1815) with maximum cooling of 1° K occurring in the spring of 1816. The calculations also show significant warming of the stratosphere, with temperature increasing up to 15° K at 25 km in less than six months after the date of eruption. The important effects of the Tambora eruption on stratospheric ozone and UV-B radiation at the surface are also mentioned. 相似文献
19.
Magmatic Processes During the Prolonged Pu'u 'O'o Eruption of Kilauea Volcano, Hawaii 总被引：4，自引：1，他引：3
GARCIA MICHAEL O.; PIETRUSZKA AARON J.; RHODES J. M.; SWANSON KIERSTIN 《Journal of Petrology》2000,41(7):967-990
The Pu’u ’O’o eruption is exceptional amonghistorical eruptions of Kilauea Volcano for its long duration( 相似文献
20.
Annalisa Cappello Vittorio Zanon Ciro Del Negro Teresa J. L. Ferreira Maria G. P. S. Queiroz 《地学学报》2015,27(2):156-161
Pico, the youngest island of the Azores Archipelago (Portugal), is characterized by a central volcano and a 30‐km‐long fissure zone. Its eruption rate is the highest of the Azores islands, with more than 35 eruptions in the last 2000 years. Here, we estimate the lava‐flow hazard for Pico Island by combining the vent opening probability derived from the spatial distribution of eruptive fissures, the classes of expected eruptions inferred from the physical and chemical characteristics of historical eruptions, and the lava‐flow paths simulated by the MAGFLOW model. The most likely area to host new eruptions is along a WNW–ESE trend centred on the central volcano, with the highest hazard affecting the two main residential zones of Lajes do Pico and Madalena. Our analysis is the first attempt to assess the lava‐flow hazard for Pico Island, and may have important implications for decision‐making in territorial management and future land‐use planning. 相似文献