One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
8 U; J6 u3 X2 U1 jtvb now,tvbnow,bttvberuptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 5.39.217.77) n% M3 i; s: S% Q' M
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.公仔箱論壇% M9 V8 Z {8 k! Z' Y$ r* i$ d! n
Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
' }* z) ?1 W* v2 C, Q& `6 B5.39.217.77erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
1 X; O. T) A" W8 @5.39.217.77and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
6 X( S) K' q% l" [' ^. X5.39.217.77They 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 tvb now,tvbnow,bttvb$ h- O! J1 P1 D" t, N
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。2 \5 I! u7 x) J6 R$ u0 D
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash & T3 t5 s% d; u; q% x H$ q5 R
plume reached as high as 50,000 feet.
9 |/ r1 `; [0 j; r公仔箱論壇tvb now,tvbnow,bttvb( z+ t, q% i9 E. |' B2 b4 w! _

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7 ~+ r/ G! I' 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。Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
- D% r* g i; t* y& h* Z' g+ N7 z) _tvb now,tvbnow,bttvbsatellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
% u+ p% C; X* G/ B9 F. X5 ?公仔箱論壇years. The island’s jagged edges were created by massive avalanches.
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% e' v- U% I4 q' R( G: J* A; J' B4 Jtvb now,tvbnow,bttvbAugustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring
' L. a: ]3 o2 _1 F# J4 sTVBNOW 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 Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet 公仔箱論壇/ m; h4 D, I2 J3 b( B7 O
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of 0 X2 ?2 R' M+ k8 {; Q( z" U
the continental crust, creating magma that drives the volcanic eruptionsTVBNOW 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 S) B. g: {' \+ k# g
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. U0 [7 A3 X2 U. r, _( L6 LAstronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
0 Y$ L0 S0 e2 V% S/ I5.39.217.77in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.tvb now,tvbnow,bttvb) i0 |2 L; p2 ` c, w
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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
$ S% l% c' ?3 q* d2 Vtvb now,tvbnow,bttvband 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。& L' s7 W$ _) U- u" c8 L' l$ V! _) A
as a pyroclastic flow.0 v7 f. n2 y6 P, |, t
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。; @; P% |! }; A( v$ Z. d
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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% ?# ~: U7 c$ }7 ftvb 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.
7 t. e9 ?! E' s/ y0 Ktvb now,tvbnow,bttvb * A shockwave from the eruption could have blown a hole in the cloud deck.# K: X8 P9 |' _, q! G% _
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.! T5 r8 Y6 Y: m" }8 Q$ f7 x
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Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet. 公仔箱論壇9 z" n5 M1 h# B1 i# ~, \
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
' R& D# t4 @: ]5.39.217.77 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.tvb now,tvbnow,bttvb5 ]( J6 o# `3 ^4 ~
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0 l q- P9 C3 a7 I) h7 VMount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in5.39.217.77! k x: H/ I* `( t6 F# y1 [/ N
the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one
: \3 O( G0 d+ _* ~; S) s( z$ _$ _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。captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
' K) e5 u# n# Z% Q: h9 uthis picture are from forest fires ignited by lava.5.39.217.776 @7 Y V- G* c$ j# g S
4 E# R0 Y1 j8 `# C9 f6 }* {" Y+ | W/ v) ZEtna 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
& p0 M; [: a& h8 e5 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。also be the oldest-known active volcano.tvb now,tvbnow,bttvb! x, l, a2 n/ c1 t" q7 J w
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+ ]+ B( T4 V) r! K5.39.217.77TVBNOW 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。! u0 ^* S6 V: K% X2 [6 J
A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high tvb now,tvbnow,bttvb. m9 T7 v# `0 ^) B: K9 z
and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.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。" d: Y0 V! a) f h
Q u7 {& O4 J7 m6 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。 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( b8 b# M" I5 k/ `
* b7 F; x4 T8 }, _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。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。5 o" O: B' U* a$ p: N* h
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 9 W2 v0 m6 d( j/ Q3 @3 ]
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
! ~8 b/ [5 t5 X0 ]# b S) oof frequent activity. The plume reached heights of around 30,000 feet.tvb now,tvbnow,bttvb6 W: R6 c+ x( r! p7 g9 g: Q
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This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the tvb now,tvbnow,bttvb- H# {/ q- e- \+ @4 h. Y# ]
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.1 f b9 O' e1 I; z) |; R$ F) N+ {
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。' P" P% O( w3 l; c+ r( E8 y3 ^
Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic 公仔箱論壇& z2 O0 t/ a/ f( e
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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5 K: C) @% Q1 w5 I公仔箱論壇 5.39.217.77: ?* U* D# y# T& E6 f
8 w* o! a+ O# t: X9 mTVBNOW 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 ' e% J/ V$ G$ W) z
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
& c+ K/ {' t* Qformed 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 ! V, ?" u5 E& H3 W' g: Y( U
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.公仔箱論壇! h* _ }" l1 k0 w9 s ~
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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.
) P" }/ K6 K" @# t T- [$ h i0 s7 W5.39.217.77A 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" O# L: r, A# e* U* A2 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 R. Z! k+ B- P% u0 P& \causing avalanches of debris into the crater. |