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。1 ?, K% h# G4 |% S# s( B0 g5 P% ~7 Z
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 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。# f0 u q9 b b% M% s
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
/ x1 |1 O6 n6 a( @+ T公仔箱論壇Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
0 v# e3 N( z# U9 |! B2 Mtvb now,tvbnow,bttvberupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
6 _/ T: g5 S5 a! S2 [tvb now,tvbnow,bttvband explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. 3 f1 _, k/ Z) f/ h9 E! N: f* V
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.
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; O* F8 ]' ^- l% Q( Ltvb now,tvbnow,bttvbMany of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above ; F" D9 I+ x$ ~; H! H; @
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewastvb now,tvbnow,bttvb" Z0 R M# D- k) e; m) {
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash 5.39.217.77:8898, z [1 L. e8 f1 y% @
plume reached as high as 50,000 feet.
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* V X0 ]* V) h) u& _4 P% B+ htvb now,tvbnow,bttvbAugustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
~( G1 i5 z5 e4 ~4 w. A! i. P2 k公仔箱論壇satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
3 ?, z5 f4 _# yyears. The island’s jagged edges were created by massive avalanches.
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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
. Z' v* @0 w) M+ j W2 htvb now,tvbnow,bttvbof Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet tvb now,tvbnow,bttvb, l+ G* ^: B! q% ?* y+ r4 ~
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。1 @) J2 ~0 Y- V0 a5 a+ C" {' S
the continental crust, creating magma that drives the volcanic eruptions5.39.217.77:88984 O$ S6 ^, }! F/ Y4 Y# R
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Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
2 j% H1 ~8 d8 V6 din the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.
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( X# L7 `+ _* Q0 f) M0 [" d" XThe smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising ' b2 t3 B* F1 s9 s( D, S
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 公仔箱論壇* i: z9 u9 m1 R% c: [2 i( q* o
as a pyroclastic flow.公仔箱論壇, L& L4 K4 T/ G2 @8 `
" F8 h8 I9 f+ R/ c3 z; S0 ]8 O4 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/ i$ z7 ?' A/ E+ i* z+ _/ a: c
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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.
( y" e3 _ m4 s& F- @. H+ T * A shockwave from the eruption could have blown a hole in the cloud deck.公仔箱論壇( K9 i& e5 ? h" F" ~" `
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.& p' V/ i2 \* D1 d
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Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
& I& A# I0 K" \7 u' X" F0 |& QIt continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
6 L% H( g8 k( J0 \$ H% {1 Etvb now,tvbnow,bttvb 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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- v) ~* G+ g2 y公仔箱論壇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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Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in) r, q8 o; ?# }8 p z# M3 Y
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 Q2 j5 b4 \. t" ]# x5 [4 Wcaptured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
; E6 m! U4 o* P u( j4 k: C K$ [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。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
: g2 F+ h& {3 i lalso be the oldest-known active volcano.tvb now,tvbnow,bttvb/ m# F j0 _6 @& W G. Z
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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
6 P. C2 ]7 t9 Land 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.
/ n( |. e2 x W9 t5.39.217.77:8898The 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
) m' h V4 X2 l- t! F8 v* V$ @tvb now,tvbnow,bttvbmultiple 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: e+ J. g1 Z/ k# Q3 P' F A! T
of frequent activity. The plume reached heights of around 30,000 feet.
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, S" x( E k* T公仔箱論壇This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the 5.39.217.77:88983 `3 s5 W) d2 F7 Z! S
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。0 \9 ~9 c" G3 d# l
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Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic
6 e7 Z7 H; a/ i/ [# C! Sflows 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.
& K6 g: A9 ^/ l$ W, 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。
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% ?8 O/ `0 Q% o, R E% uTVBNOW 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。
; w' ? p3 q) ]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。This image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra * e0 s0 L( Z& g! z3 x7 c
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 5.39.217.77:8898 G- S% n6 W& R
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。, ~# f3 }6 J C8 K6 S# `
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
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) O) `0 D/ a P b% Z3 V& Dtvb now,tvbnow,bttvbNASA’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.
) n+ j) V6 z. ~' d0 r- k) [ k5 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。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 tvb now,tvbnow,bttvb* p' r: i6 h, k7 N/ J) K
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, $ D$ T( K7 V0 K; k$ i* g# b# \
causing avalanches of debris into the crater. |