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。; ^7 Z( l( Q N+ I
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 公仔箱論壇) s1 f+ f% r( \
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
% p8 j j3 U3 M! f* U) |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。Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
2 L9 b8 p, [5 _4 [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。erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous tvb now,tvbnow,bttvb7 ?. Z% O. {8 _' e C. }' O+ R; J
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
; l) y7 C# z: O' J q$ E3 f- d5.39.217.77They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape., W" Q9 N8 _, P$ r9 `; w' Q5 w
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, \7 p1 R, H' z1 P0 D, [* B- j- C5.39.217.77Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above
6 S+ q% V5 X- q- s7 t6 ptvb now,tvbnow,bttvbof Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
b! F5 r$ i9 u# G2 s+ e3 O6 etaken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
; t* M C8 E! @# S" Nplume reached as high as 50,000 feet.
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Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra 5.39.217.77# P9 a6 n% G/ B0 K1 J/ I% d# P- [+ B3 l# A
satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000 ; f- r' L6 D( X# D% R5 N
years. The island’s jagged edges were created by massive avalanches.5.39.217.774 A' l8 _/ v2 n O2 d+ Z: ~$ J
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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
+ ]+ Q& E, e V s# e公仔箱論壇of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet 5.39.217.775 E0 d& S$ t( Y. a! g+ `
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
5 w, D% d V& {$ D/ i; V6 @5.39.217.77the 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 ; c' y# W& W, P* f2 J: ~4 s: R) `
in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.tvb now,tvbnow,bttvb o% S# |1 I$ v2 E
3 k# j% b5 E7 a% R+ h* r$ 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。The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising 公仔箱論壇/ A) y4 V- m& ~* P( z4 f
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
2 H+ \9 T, P. t' t A 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。as a pyroclastic flow.
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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:公仔箱論壇6 l z2 C7 I% T) n7 o7 L* p
( a' ?, d; N& Z9 \ * 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/ Z- R& O/ `' ^/ D6 p7 }5.39.217.77 * A shockwave from the eruption could have blown a hole in the cloud deck.
3 R. Z5 \7 N) ]) k2 `tvb now,tvbnow,bttvb * As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.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 ~$ E* a }( W H1 g* _
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Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
. i. l- [& b/ z- t, `tvb now,tvbnow,bttvbIt continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 whenTVBNOW 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。- F& A4 F% g+ t
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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$ F& f- W# ?9 Z- {3 G1 K" X- qtvb now,tvbnow,bttvbMount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
2 P4 t3 c4 f3 S the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one tvb now,tvbnow,bttvb. X2 E! `# n U) V- `- Y% r
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
' u" z2 O6 e1 t( q$ G7 a' Ithis 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。 A6 K- i: P, K O: I, n
| y) ^1 g* Rtvb now,tvbnow,bttvbEtna 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 maytvb now,tvbnow,bttvb) b }7 }( X f$ N2 v( \. h
also be the oldest-known active volcano.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 h' ` ]- F7 P( `
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。, W4 x! w, M k; Y, H# g
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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 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。3 L) @! Z- v) O7 W
and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.' p. g0 w+ b- W" [ {/ o) O
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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
, b X; [0 b3 p1 F6 o" _4 gThe 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
2 `, ?+ D9 @9 t7 A* i$ V/ p$ v1 s* Jmultiple 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 n' Y( F$ |: ?! z/ s4 aof frequent activity. The plume reached heights of around 30,000 feet.5.39.217.772 E2 q: }2 _' O' Q
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% E8 j( Q8 ?8 [) y& L1 o5.39.217.77This 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。: G) A5 u6 F' V; ]5 r- k
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.公仔箱論壇# n! i* ~6 v$ j6 m, ?8 `' f
8 v+ q6 c- ~: R$ j% L; ]$ P, d5.39.217.77Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic
Z9 Z- e9 c v0 H. @; ^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.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% l1 U. y- w0 S" a) q8 d
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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 公仔箱論壇 K1 S- P, |6 u7 D3 d$ Q
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
) ~' L% g# N4 o" K% }' ~- x) L4 m- 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 5.39.217.77$ j( _3 E" {# {! A) F
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
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q7 d: K+ G# k: `( ]) m' P q V& ENASA’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.
$ D0 d" g O; l5 d1 M& o0 Z5.39.217.77A 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 , ~) u, D2 P$ `4 d; J6 Q1 b
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,
% A0 w7 l, Z* k. @9 V7 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。causing avalanches of debris into the crater. |