One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic 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。% X3 B& C2 v) j" W
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
# j' w9 ~* q3 L: J5.39.217.76active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
( ?+ ]( i. Y- a! ^Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens, 3 D, G2 Y+ w) }2 q, {
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
1 w% T6 }& z4 _4 P, n5 x5.39.217.76and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. 7 J0 v" X% M" f5 n% t7 v
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.公仔箱論壇9 P- z" j8 p. ?
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' U3 W" K! o5 Y P: v" L& Ntvb now,tvbnow,bttvbMany of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above
/ E: c0 `) @; |" v' [7 f( Q6 TTVBNOW 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。of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
7 M" U6 p: T7 q( b$ PTVBNOW 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。taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash - \0 g# a1 N- C$ t6 e
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
2 d: ~- R2 ^# y/ B. T: Y' Xsatellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
5 u9 H1 w& A3 h& W0 L( S& j- [5.39.217.76years. The island’s jagged edges were created by massive avalanches.5.39.217.76. N$ I8 S+ l9 Z3 a- e
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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
" f$ O8 E" L2 L+ F$ m; K% U) z: V2 W0 h公仔箱論壇of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
9 ?( y. w/ P* K) E L pTVBNOW 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。ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of tvb now,tvbnow,bttvb: K H, ^1 a! D n/ z# L" T
the continental crust, creating magma that drives the volcanic eruptions
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1 i2 d) V$ J. A9 IAstronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano 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。6 ^6 h: H' q; j Q( c* u* `8 o
in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.
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The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising
% U( x6 z' ?* ]: ~9 p4 mand 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 : K8 c# J s! h
as a pyroclastic flow.5.39.217.76& ^: A$ p- G7 e$ l4 [
5 q- X. ^- L8 L6 w" qThis photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up:
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$ Q6 u2 Q$ P1 V/ g5 `% qtvb now,tvbnow,bttvb * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.
2 d2 \* f- i U9 @ F6 _公仔箱論壇 * A shockwave from the eruption could have blown a hole in the cloud deck.
' Y0 ]4 m8 L! s9 h( G/ F0 ^ * 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.
1 M4 T7 D, i& U5.39.217.76It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
$ X$ j6 c2 C! aTVBNOW 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 ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.: D! w# M3 K$ s( Y1 f' O/ 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.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。" w) D% ?/ I2 r0 |; p
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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
$ m! @% h+ S4 \& M公仔箱論壇 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% F2 {& v, M0 I* f& ?5 u3 ^
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in 5.39.217.76, X- c/ Q" s" C4 ^0 r' F: n* [
this picture are from forest fires ignited by lava.公仔箱論壇0 ~8 o5 x" R# p' A- j
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Etna 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
; V, V. `+ E8 T8 ]3 V* i, nalso be the oldest-known active volcano.tvb now,tvbnow,bttvb& E3 O1 b( d) }- I5 S/ D! [: }6 H
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! @' n1 ~4 I2 Z1 {9 K E! Otvb now,tvbnow,bttvbA NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high
+ ], X: O% O, _9 @5 t! aTVBNOW 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。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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: u* w# `' Z3 P8 e公仔箱論壇Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
& @1 T2 p8 z) ` jThe 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 tvb now,tvbnow,bttvb. V5 O9 a: Z' C( s W) m$ `4 d# K
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
* {$ W. D M- n/ H- C: V! u& m8 oof frequent activity. The plume reached heights of around 30,000 feet.
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+ V4 G D" H1 G9 i6 h* q9 cTVBNOW 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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% R. E7 n5 [% U4 |/ w$ _9 m& ^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。This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the 5.39.217.76' x7 B6 N& o- e; Q" D* l
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.4 X1 P) b4 p: _& [+ l6 `
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Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic
, J$ C8 _2 Z4 M p$ j8 |! ]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。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( D U: g2 M& `0 Z2 K$ A" d
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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
0 ^ R/ W5 K) _8 H; ^# 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。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 公仔箱論壇1 [! U8 w$ {! d
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 5.39.217.76+ ^# }: M1 V$ H+ l
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
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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.
' ~: D- v. b! o) y- ]& w& z5.39.217.76A 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
! L4 L6 E+ |9 N, rthat 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,
' c( y: J& Q( `+ `4 x( v% i2 J5.39.217.76causing avalanches of debris into the crater. |