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。% m, Y9 n6 X# o; n( {
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
% C6 ^. H! m. M4 Ctvb now,tvbnow,bttvbactive each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.公仔箱論壇$ H6 v2 t# Z% ^5 p, J9 s) I9 A
Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
5 F3 g5 m! ~' q$ e公仔箱論壇erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
! ~/ H5 W8 _7 d4 mand 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。6 ^: w8 q! O; W7 u: ^: g
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.2 [9 r2 H2 ?- A4 s# E/ l( J @
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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, @' s' m8 l) O" p- b' f" s% D
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
2 i% s6 x1 u+ v- c& G( p+ Staken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
, t9 T) [- W% E; g! X) U! Cplume reached as high as 50,000 feet.: T% p* I% _0 d! @7 }5 u- Q
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; ?9 _7 M2 G4 `9 l' m: m9 H* p* V* U$ L公仔箱論壇Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra tvb now,tvbnow,bttvb* B: o9 F: k1 H0 ]2 ]4 r8 U3 T
satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
. _) {& d7 n9 S6 v' [公仔箱論壇years. The island’s jagged edges were created by massive avalanches.5.39.217.77:8898' m5 m0 @! U W# ]! P
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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
6 V' E3 ]' D9 Eof Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
, A) O% f7 `& Y3 m: Locean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
6 @1 l1 d4 e: L) P* l# c6 xthe continental crust, creating magma that drives the volcanic eruptions5.39.217.77:8898; u3 G6 j& c+ O c6 H; X+ B
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( Y6 M3 A' a6 YTVBNOW 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。3 b- b* K( [# u- K2 Q D: G
Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano ' w8 q: e' e( l% ~5 s
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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! I: n `* S& WThe smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising
& x+ s: u" z: G! k" a `1 Yand 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
* F/ d: N/ S( e7 _3 ^" ~as a pyroclastic flow.
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4 ~* [. b( _' ?$ {3 Q% M, X2 \This 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,bttvb1 z* ?5 ?# D, l; w2 E
! i0 l9 W% y( T, X) k a5.39.217.77:8898 * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.
9 r/ ]/ }9 W9 w9 l* T! d3 z+ Y5.39.217.77:8898 * A shockwave from the eruption could have blown a hole in the cloud deck.公仔箱論壇+ C: T) `; y; v; Z" x5 p8 ^( [
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.
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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。; t X) |; A3 C2 E0 V
; o5 Z+ J) n1 G: p9 z( g! H# v- i公仔箱論壇Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
; C$ v. ~3 A7 E6 u! \# d. r5.39.217.77:8898It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
/ K+ I1 y3 D/ O2 C. X' P% Q5.39.217.77:8898 the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.. B# M8 X+ l5 F8 h9 Q v7 r
9 d/ g N; g& y! f. N; WRedoubt 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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Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
( p) C8 E6 b. O4 S5.39.217.77:8898 the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one 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 n2 s7 Q) ~- ]# G/ [$ O
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' C# \% n( H$ Q- I* K( ?
this picture are from forest fires ignited by lava.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。 L' Y8 n# _4 Z0 ?3 n6 j* @% U5 k0 N: A
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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 mayTVBNOW 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。, }' K* P. |- B- s8 B
also be the oldest-known active volcano.
* J6 k& e- O) S# I+ g, C) 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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A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high
4 V. l1 n' L3 l0 v7 Htvb 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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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
* `/ h8 f! R8 a8 b6 ^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 公仔箱論壇4 Z! |7 {3 M- l ^) r/ m# {+ W9 `- z
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( ~. q8 l6 p8 n+ [/ L: V) Q
of frequent activity. The plume reached heights of around 30,000 feet.
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6 K w% G; N1 \2 J& e2 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。 ! r9 t9 \4 I2 s z" T$ ?9 U
% @' H6 L9 w/ _4 ]' l5 xTVBNOW 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
3 i- O: S6 s, h, L) @/ Vwest coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.3 m7 t1 H6 I) Q3 b/ Z' B
; W4 u: `/ m. |" w2 W( u5 R公仔箱論壇Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic tvb now,tvbnow,bttvb5 X A9 q$ K; h0 v1 q
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% V1 f8 r5 q+ p2 T/ A) H8 i1 Y! \8 K
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% M0 v* Y v1 s+ Z" h, Q% 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。This image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra
& M; J( K; o1 Q: j' l9 k4 [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
7 H$ V+ ^ I2 v; Uformed 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 / F: R9 `( l' [6 @0 Z7 P0 W& p
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
5 o# S) n- }+ }/ L: M) i- 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。$ e+ \1 ?# v! ]. a+ N6 O8 o
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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。7 Q/ t- x& R$ E
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.
6 r8 ^8 R, N) Z m$ Z$ O5.39.217.77:8898A 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 tvb now,tvbnow,bttvb" F* q! A9 y, g4 p+ L
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, + B; ^& X( k: v# u9 K
causing avalanches of debris into the crater. |
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