One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
6 [2 v8 f. V% D; D! R6 B+ I) U5.39.217.77:8898eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
2 C! G) a! e% d5 r& lactive each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.5.39.217.77:88984 E/ K) T5 _# }% Y f
Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
( F4 Q. F2 \9 w7 ?, {4 P. qerupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
8 }' ^2 z; }0 iand explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
2 y, d5 R+ n- r8 Z* |TVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.公仔箱論壇' ?, V% v" m9 J" y2 l: V- `* D
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2 ]% d( Y, o8 W5 `Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above 公仔箱論壇) D4 k# s: A5 K, M# \+ \1 j6 H
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas5.39.217.77:8898( [6 B: N2 g1 ?2 {# `8 P
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash tvb now,tvbnow,bttvb5 N' G* n* R& S y6 }
plume reached as high as 50,000 feet.
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Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
8 b# O4 W! |1 }$ I ]3 ]5.39.217.77:8898satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000 0 P9 K. H. k3 j
years. The island’s jagged edges were created by massive avalanches./ [1 @; H9 f! X% C; d9 p9 f! I% v# v* \
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Augustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring
7 M* b- B% l: F4 h; M) b: [of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
+ O4 k3 V/ [0 t; ?" l公仔箱論壇ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
, Q! ?1 V+ k" o/ v8 K1 E( |TVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。the continental crust, creating magma that drives the volcanic eruptions( Y4 I) c: [. G `( N0 ]+ m
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, b8 ~* l' Q$ D, A6 lTVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。TVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。0 G$ c( t- N! J* s. q
Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
. f& {! `$ H' sin the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.公仔箱論壇: A. j& z/ I- V) j2 Y6 z- y z& ]
$ @/ G# s' k8 _3 y% g" T4 c公仔箱論壇The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising
& M) |. V% S' Y$ w2 pand cooling of the air above. In contrast, a dark gray cloud of ash near the ground is probably an avalanche of hot ash and rock known
' [9 Y( k$ u3 G( Y/ nTVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。as a pyroclastic flow.5.39.217.77:8898# h: J! P" g" z: ]* M' Y) H
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This photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up:TVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。9 q0 p; Y, N' Q' \* y$ t
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* It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.
' W' T% E" o+ C, l+ L6 H * A shockwave from the eruption could have blown a hole in the cloud deck.
: Y+ H( b+ x; Z( H% |公仔箱論壇 * As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.
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Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet. + [- m) ?" f: y% A. o9 ]- q
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
* G3 [& f7 |( Y' ]8 B) d the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.公仔箱論壇% l6 ]5 q/ g& K9 N4 N
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Redoubt is a 10,200-foot tall stratovolcano 100 miles southwest of Anchorage in the Aleutian Range, west of the Cook Inlet.4 x8 R" O& m; [+ i: B' f H" r% Q
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Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
A# ^4 f; M( i2 R* V% x the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one 公仔箱論壇! j, i1 }* d+ W" t0 L+ `$ s
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
$ ~0 Y: m3 q; o; w' E. z4 I公仔箱論壇this picture are from forest fires ignited by lava.
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/ R& ~7 a. i( z% Ntvb now,tvbnow,bttvbEtna is a stratovolcano located on the island of Sicily. It is one of the most studied volcanoes in the world and. at 500,000 years old, it may
9 U- `+ P: }( B/ a/ Ctvb now,tvbnow,bttvbalso be the oldest-known active volcano.
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A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high
: }# K8 F2 b r8 I c8 D" iand claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.公仔箱論壇( o/ M% q7 H; `/ L( i* E; n8 `" d& t# W
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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City. TVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。! y& w$ e" i0 B0 o6 k
The second highest peak in Mexico at 17,800 feet, this glacier-covered stratovolcano has erupted at least 20 times in the last 500 years and has caused
# e; C* `. o6 y$ i0 c5.39.217.77:8898multiple evacuations of the city. This eruption in 2001 was caught by astronauts on the International Space Station, near the end of a seven-year period TVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。2 _2 ~8 o5 N1 e" s- L
of frequent activity. The plume reached heights of around 30,000 feet.
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This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the 公仔箱論壇% H( {+ O. L" g' ?: ^- e8 ?
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.tvb now,tvbnow,bttvb- _+ s" g; X% L. ?1 @7 t, }
S- Y" @$ Y0 S( \5.39.217.77:8898Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic : Z/ a% c- c" g% w4 t" f4 ?+ P
flows and volcanic mudflows called lahars. The caldera is relatively small at less than two miles wide, and sits on the flank of the larger Michinmahuida volcano.
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This image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra
& {+ ~# @, w, U; z5 r1 r+ Ois a shield volcano, which are made mostly of previous lava flows and tend to be broad and gently sloping. The Galapagos are part of an island chain 5.39.217.77:88989 E: I# n/ X$ \! _0 M8 `
formed by a hot spot where a plume of hot mantle rises up and melts the base of the ocean crust. As the Pacific plate moves over the relatively 5.39.217.77:88982 q- n2 k0 x4 n7 U! {% c( m
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.8 X0 W# k, h- P) j, W: l1 m5 m
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0 [& i8 c; S0 M6 w. g! BNASA’s Terra satellite snapped this image of Shiveluch volcano erupting on Russia’s Kamchatka peninsula at the edge of the Pacific Ring of Fire in 2004.
. o% x; D$ }/ y4 T5 U: \tvb now,tvbnow,bttvbA lava dome had been growing in the volcano’s crater, followed by intermittent eruptions that lasted weeks. Shiveluch is a 10,400-foot-high stratovolcano TVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。% n! v9 \& I" i# Q$ H
that is at least 60,000 years old and has been erupting fairly often for the past 10 years. Its dome has collapsed multiple times, most recently in 1964, TVBNOW 含有熱門話題,最新最快電視,軟體,遊戲,電影,動漫及日常生活及興趣交流等資訊。, {1 y- X) D* _" z# S* `
causing avalanches of debris into the crater. |