One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
* n1 T( q9 b$ ?9 R9 I& d n公仔箱論壇eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 公仔箱論壇" W: G( a; e/ c- o- I
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
8 F4 @' m/ ` l) h( v0 m; F& C5.39.217.77:8898Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens, 2 \3 U3 Z- g8 `9 k5 x) C S" o& V
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous 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 X/ ^9 B" a4 m
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
; o' J5 b' P7 u; h2 R$ 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。They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.
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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 T! I# {9 X* T$ d' @" A6 M% m: P
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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# k6 b) R7 {5 r0 M% D
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewasTVBNOW 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 e* |' J+ E7 N5 ^, q4 S
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
: S) X' \0 m1 W1 h3 a公仔箱論壇plume reached as high as 50,000 feet.公仔箱論壇9 S$ H' d8 x5 I7 _
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。+ J9 W: G9 V1 R" D$ ^2 W% K! l, r. Q: v

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* J$ C+ z! S9 p8 L$ Z$ ]0 U- B. J# kTVBNOW 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
0 f* e0 R+ @& G, S9 q9 h9 I6 Esatellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000 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。# o4 N; y* p/ ~. F5 _, o
years. The island’s jagged edges were created by massive avalanches.公仔箱論壇9 \3 p. l' L C! x: B9 I r( ?9 _
$ W# f' W1 P" P8 t$ m p公仔箱論壇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+ ]- B/ r C8 R, j, |
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
: }* F4 L! @/ w- Wocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of 4 f3 o/ `, A: l; h
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
. E9 N6 g- F1 a7 q" 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。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 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+ {% C' i8 e0 Z+ P
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。! H3 n! ?" ]: l+ n# l+ s) r
as a pyroclastic flow.5.39.217.77:8898( l, y0 B5 [$ A( s8 @
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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:( k9 O* ^8 \1 ?: E) N
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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./ @6 |# q' X) y$ M" {' Y( u4 t
* A shockwave from the eruption could have blown a hole in the cloud deck.
$ \* {# w, y- \( Z+ ^ * 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. " I5 ^1 D% F( O* R
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when公仔箱論壇% K6 s% E+ Q5 b7 Q# `2 Y8 K, x" { V
the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.4 ]2 x8 M- w/ _6 R% ^% H; X
$ a/ i: T* D! ~5 B8 }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。Redoubt is a 10,200-foot tall stratovolcano 100 miles southwest of Anchorage in the Aleutian Range, west of the Cook Inlet.5.39.217.77:88988 u R% b& D* O
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1 @9 Y! E. G D, S' d公仔箱論壇Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
/ P s1 a# v" `. A' _tvb now,tvbnow,bttvb 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9 `5 y8 R: N5 j/ n8 b% ^
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in tvb now,tvbnow,bttvb# u. b4 W2 q. }! r
this picture are from forest fires ignited by lava.公仔箱論壇6 e7 ~* z; Z9 t, Y4 D% G' b X
6 D; h& c" A; q9 q& q' O7 M5.39.217.77:8898Etna 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 may5.39.217.77:8898% Y) A) q5 h$ g: Z6 g5 p3 r3 h
also be the oldest-known active volcano.6 M. J" u% Y- b; v- R
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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
2 U/ s5 V, P+ [tvb 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.tvb now,tvbnow,bttvb. V3 x# ?& ]) p n
2 B$ p7 J& a! H, D$ k, oTVBNOW 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- R3 {' ]- `4 y6 m% p0 h# v5.39.217.77:8898TVBNOW 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。 M0 p" A! @7 N9 y1 Q1 p* u( W, F
Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
/ H6 C$ ~ r, d7 w# c) ~" v- b5.39.217.77:8898The 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 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。. Z; w& @( u: 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 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* @/ ~8 [- E9 B! Z6 d
of frequent activity. The plume reached heights of around 30,000 feet.公仔箱論壇- ^7 e6 q* C. H {
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This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the
4 z ]$ `, {; b; r8 H% b# wwest coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.5.39.217.77:8898, t2 N) J. \# P/ G, b! n
( u+ C4 n6 j2 s+ p, OChaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic
( U5 U1 [9 Y$ x* nflows 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 5.39.217.77:8898# Z% I3 D, l) @" {8 b
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+ {9 _; n# I0 S% ?. h. }2 u6 m
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 tvb now,tvbnow,bttvb; J9 u- M* ^' U) M' l6 v8 J( ?
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. 公仔箱論壇+ {" _* X, ?, [$ p& P
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 公仔箱論壇- O/ D. Q, a0 T6 q+ M) |
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, 5.39.217.77:8898: ]- Z( Z' w2 ?, S
causing avalanches of debris into the crater. |