One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
( n; d4 |$ _( f' k; J- L: M- J( ceruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
, Y' Q4 |, p2 M }www2.tvboxnow.comactive each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
1 Z' v0 ?9 W) V) gtvb now,tvbnow,bttvbSome volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
2 V7 W2 S& g; [2 Z0 Q: Derupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous ) T, |+ U# E$ e. d/ g) s0 a
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. 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。* S" p B6 [6 b4 O; }/ R* E
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.
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Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above , {6 A9 [0 @& X+ U! n, q$ H
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
$ M! `) \4 ]1 j# [8 L U2 l! F公仔箱論壇taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
q( L, r1 l, wplume reached as high as 50,000 feet.- j$ p: _* d5 b% n
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Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra 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 O3 @/ J/ I7 b8 P/ Q% \2 n
satellite 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, B3 B. E. P+ [
years. The island’s jagged edges were created by massive avalanches.tvb now,tvbnow,bttvb5 S# g3 G1 T, O* q6 g
9 W" O m$ a. C+ ZAugustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring 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 T/ u, T$ y+ o# N
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet 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。) a8 |0 U9 Y; f: f
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of 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。, ^5 h' Y9 j2 w# ~+ T
the continental crust, creating magma that drives the volcanic eruptions
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Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano 公仔箱論壇/ |$ }, l0 G, H" @. q
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 tvb now,tvbnow,bttvb8 W) e5 |& I4 y! O: L7 V, [
and 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 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。' V- d, A; B8 \0 z5 C2 T2 z& c, ]
as a pyroclastic flow.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。5 v, j8 [& v1 P ^$ L
6 F3 N3 m$ K$ w, T" ltvb now,tvbnow,bttvbThis photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up:tvb now,tvbnow,bttvb) @. h) K( i7 c2 N# |' Q
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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.公仔箱論壇& ^, N1 j" i2 m) {. V9 U9 b$ _
* A shockwave from the eruption could have blown a hole in the cloud deck.
1 A7 I, u# ~9 h8 N/ q- b7 f * As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.
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, k7 B2 t% f9 b' @+ r- m$ Utvb now,tvbnow,bttvbAlaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
5 s3 e4 P4 O3 J" O+ dIt continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
7 N d5 Q5 R" D 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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* @, h# @* w8 C" c# lwww2.tvboxnow.comMount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes inwww2.tvboxnow.com& }" a# [6 z; J
the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one ' F+ {$ P1 D/ x2 N; `
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
1 R" X9 H* `) n0 c" P" l公仔箱論壇this picture are from forest fires ignited by lava.
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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 h/ w x) n S$ t/ x
also be the oldest-known active volcano.
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6 ~. ?3 F2 \% w: I: d8 yA NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high
. k, e- d" K/ j) c' hTVBNOW 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.公仔箱論壇 ~# {2 F/ Y$ |) `' g# |
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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
1 G. z- n# s' P. S# H: c1 L6 J% IThe 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 ' d; j. {! s6 _6 V& p, W
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
, E& E3 P+ X6 E# ^+ N8 R0 W公仔箱論壇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 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。! x4 r _0 |4 }
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.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。! O8 ^* c- _0 z0 o- T
9 s! K T O [0 y/ fChaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic
' r$ _9 V8 K. _7 L m ^. vTVBNOW 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.
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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 : j1 f) G. y; i
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 www2.tvboxnow.com* q/ ]/ |- E: Q( S9 w, Z
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 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。8 M N! i/ C$ s" @' c1 k1 ^
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
; d4 i2 L8 c! m5 o9 s) ] t2 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。2 n. d% m: t% R& r

: ^' {/ d5 C# [1 l! wtvb now,tvbnow,bttvb
4 u( i+ \8 q% K! F8 N! R! {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。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. 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 T! W) {. {& c# ]1 ?6 j; n
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
7 D/ C" f6 _2 ^% t: v( ithat 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, 0 T7 \+ R e( F% ~: y/ m9 q5 V$ I
causing avalanches of debris into the crater. |