One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
[ T. F. p3 [* ueruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 公仔箱論壇9 F- O- t' t6 m7 Y! L7 X; y
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.3 _5 r/ i" j( O
Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens, 公仔箱論壇; i# ]+ L" K$ ]1 {
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
, [$ y9 w' N/ U公仔箱論壇and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
- @: Q- W" y- L0 |. `4 O [$ otvb now,tvbnow,bttvbThey tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.www3.tvboxnow.com! f. x! G. q( T' O; N. N! o
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。$ ~& X& ?3 z1 G: i

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4 L) W, H2 g) f I7 `" j. q6 zTVBNOW 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。Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above tvb now,tvbnow,bttvb8 H2 A9 o Y# K# N6 D+ T% k% B
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas+ M7 ?+ M$ i- I, j/ W
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash - ?+ q$ l. r J* K6 D
plume reached as high as 50,000 feet.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 M$ O% ]5 s0 I8 g
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9 X1 n1 E- c- ~0 g+ k. e: [$ V1 S+ y2 XAugustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
7 I8 s5 S4 G* F* Twww3.tvboxnow.comsatellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000 公仔箱論壇' ]% X9 e6 Z- d7 g
years. The island’s jagged edges were created by massive avalanches.
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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 公仔箱論壇3 r) _- @. v. [
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet www3.tvboxnow.com1 T. [0 \1 w ~6 N* K) _: D
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
& [9 g( L3 S% M# `$ K公仔箱論壇the continental crust, creating magma that drives the volcanic eruptions
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7 G1 \& S' }' Otvb now,tvbnow,bttvbAstronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
|3 i8 a' R, S0 j+ y公仔箱論壇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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9 X+ M3 z2 m- wThe smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising
! t* d M7 ~! V" L' rand 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 , f6 e- H( `0 F, p3 @" R' T0 N/ v
as a pyroclastic flow.www3.tvboxnow.com( d- I* K* R6 p. P; L1 K$ w, u
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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:
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& v* L- @& h- ^) v2 P) ]+ R/ l * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.
* y! ^& I2 ?' O0 I7 ?. A' T' W* M * A shockwave from the eruption could have blown a hole in the cloud deck.
# i* M* }: x7 J9 S% V% ? * 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. ) c2 ]+ g2 q' c$ G$ x/ b. P
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
1 C) T: F! I" I4 ~& e3 s$ JTVBNOW 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.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。, X# N- U8 z0 X) x1 T* m: c) {
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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.公仔箱論壇8 M' Q+ R& X6 l9 j+ y, V! B
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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 inTVBNOW 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。+ C1 L, F! L! v0 q
the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one ( M$ _4 h1 d( u4 \% z$ H
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
?8 c; z9 c' H5 ^6 Q" etvb now,tvbnow,bttvbthis picture are from forest fires ignited by lava.tvb now,tvbnow,bttvb9 t, T6 s) S" ?$ j/ y
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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
2 ]3 g+ K6 A6 d& t/ P* Kalso 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
# ]5 k+ P3 ]$ ^6 E1 d# ~3 Itvb now,tvbnow,bttvband 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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, J0 ~5 j& S$ ?& b公仔箱論壇 tvb now,tvbnow,bttvb# o. \& F* D4 W' v
4 B. |& G9 ^ W$ I4 q4 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。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。( ?1 u; K5 K8 ~) _4 P$ q( U; z' i3 N
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 / f3 L# }" z0 J# e, |
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
' @9 d* o$ s5 B F' U( wtvb now,tvbnow,bttvbof frequent activity. The plume reached heights of around 30,000 feet.www3.tvboxnow.com8 p% h+ ^+ T" |8 c4 _
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/ n$ @1 t& Y* m# Q! U- K& AThis eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the tvb now,tvbnow,bttvb K$ s0 I' [1 A2 z$ w
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.
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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
9 V* h+ k/ f, k* hflows 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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5 q# D: c; R5 d: S/ XThis image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra
4 i9 ?$ s8 C' ?$ H$ Etvb now,tvbnow,bttvbis 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# _7 B7 x: Z+ q2 @' K* \1 A# X4 t
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
: `: \6 D" h* A: j! ~" Q公仔箱論壇stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.tvb now,tvbnow,bttvb3 s% f" Z4 @3 P9 h. ~
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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. ) f( S, d# H; p- D' A
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
* m+ i, t1 U8 g4 `2 A: GTVBNOW 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。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,
) v; Y" p$ C( P& t6 n% H) dTVBNOW 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。causing avalanches of debris into the crater. |