One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic 5.39.217.77:8898+ \# z; k7 O" G% r
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
6 }6 z. D) _# r" h. j# r8 X公仔箱論壇active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.5.39.217.77:8898: \1 _% r p4 x, n0 x$ I) {- Q: o- |5 f
Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens, tvb now,tvbnow,bttvb( o" |0 e. `! Q( @8 ^) a, E
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
) B/ H0 K8 j3 D7 _+ @* c8 F3 aand explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
4 T3 o. @: j! v# Y# F" a5 _4 @2 Q! p- atvb now,tvbnow,bttvbThey tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.公仔箱論壇3 p7 @" G* C. j# B
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Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above 公仔箱論壇" X9 z1 S$ d% J+ f8 D2 M2 Z& Z
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas公仔箱論壇7 S0 _8 c; E& D) ?* F, B) V
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash 5.39.217.77:8898. K; ~- X2 e/ z6 H
plume reached as high as 50,000 feet. R" k) f/ P- A
6 T; N+ @% q j& x5.39.217.77:8898 tvb now,tvbnow,bttvb/ Q1 Z! i3 u% t( x! Z* e# J) k
8 n* C) y/ e4 R9 QTVBNOW 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。Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
/ f* N% V: X; Z" X6 csatellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
4 h2 K- Q3 n3 x3 j7 E7 Nyears. The island’s jagged edges were created by massive avalanches.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。$ T. G9 J9 v9 u% ~. G) J) e. n
3 S* c$ n; ?: D% K6 b0 T! bTVBNOW 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。Augustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring tvb now,tvbnow,bttvb8 p0 ^+ h8 Y5 W0 v9 E* o" i* `- o, j
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
* A& B% ]6 F9 ?( A E/ m5.39.217.77:8898ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
, _2 g7 X% G. g& J" v( D/ U/ k* kthe continental crust, creating magma that drives the volcanic eruptions
+ a7 K K5 ?( c" a( {- sTVBNOW 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。
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Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
9 l6 U% L) f% e8 ~+ f5.39.217.77:8898in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.tvb now,tvbnow,bttvb" T- b9 m! ^3 b$ R3 I8 \
; I: r% S& z- M8 p$ ktvb now,tvbnow,bttvbThe smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising
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as a pyroclastic flow.; h6 I( ]- q* _- F' J' O' q& `
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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:公仔箱論壇 N8 ~: W( i/ b- J% y. C& W
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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.tvb now,tvbnow,bttvb* R/ H& ?* D( i: W# z& V7 ` Q
* A shockwave from the eruption could have blown a hole in the cloud deck.
6 m9 J0 U& {$ S& z( D" n: _: ETVBNOW 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 the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.tvb now,tvbnow,bttvb, I( @$ a1 X& u' G
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Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
8 o+ x! X1 V# [3 g8 x5 C+ ]8 k4 uIt continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
# @4 ~+ [$ V; U+ G w+ U- \+ H/ ` the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.
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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.
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- @3 V+ T' G3 ]5 J, t8 `tvb now,tvbnow,bttvbMount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in4 k7 K. a* |1 e/ q8 R7 z
the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one tvb now,tvbnow,bttvb o. ^/ ?3 L1 V
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in ) K2 ^; J" a; L
this picture are from forest fires ignited by lava.
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$ ]2 m1 b& B5 I' fEtna 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
( \& u& W+ \; ]1 `, T1 ialso be the oldest-known active volcano.
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8 b- E" l5 T* a1 e; q: a d4 \3 ?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。A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high 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。 R. W `2 W( }+ C
and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.
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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
4 x; y a$ l+ w" j; c! dtvb now,tvbnow,bttvbThe 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
% w% y: n# b! m0 y3 m( ETVBNOW 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。multiple 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 tvb now,tvbnow,bttvb( b0 R" S `6 `5 m( T
of frequent activity. The plume reached heights of around 30,000 feet.公仔箱論壇& a7 q6 W. m* n4 b, K% V
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This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the
) C* R' y7 P. W/ m* z5.39.217.77:8898west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.公仔箱論壇+ G& ^: S# U8 s9 V; N
+ b) ~- Z* S5 {) \8 n! htvb now,tvbnow,bttvbChaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic 公仔箱論壇8 w; R+ }# h4 d- a7 s
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.公仔箱論壇/ e( U- s1 ]/ H6 E) r- H% m
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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
- e) M$ K5 ^* E; d+ MTVBNOW 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。is 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 tvb now,tvbnow,bttvb- R9 G* L8 k, C4 B0 \
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
1 X" Z, ]3 j( j- @* X/ Ptvb now,tvbnow,bttvbstationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.) E- l2 P( C9 Z+ n& j
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NASA’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. 5.39.217.77:8898* B5 A- |) \8 B( i) K" S! {
A 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
! J/ ?1 N/ E1 F0 J4 x) ?' H: W5.39.217.77:8898that 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,
* A( l M# g. D2 k! C& otvb now,tvbnow,bttvbcausing avalanches of debris into the crater. |