One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic tvb now,tvbnow,bttvb3 q+ ~/ S2 L$ w3 Z# X% I' e
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
* o: _5 q# U9 Yactive each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
# ~! n) x% W' {) wTVBNOW 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, 5.39.217.77:8898. \' C; U7 Q9 i/ E
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
6 h0 L; Q+ q$ M8 R$ ^tvb now,tvbnow,bttvband 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。, F; e" X6 W9 n5 h) ]
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.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& e, a. Q6 ]0 B* h" {) k& F. o
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Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above
3 E( U; w( a& U% H4 T- xtvb now,tvbnow,bttvbof Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas5.39.217.77:8898# q' v, z0 O8 C: \8 _1 V0 Q
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash tvb now,tvbnow,bttvb3 x( p0 ~+ ~" [& O2 i! d/ @4 U
plume reached as high as 50,000 feet.tvb now,tvbnow,bttvb% g; R5 U8 W1 H* O& w
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Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra 5.39.217.77:8898( L; X- }; S3 r+ K' `5 q9 l: B
satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000 4 Q# O, ~* S2 k- ]
years. The island’s jagged edges were created by massive avalanches.公仔箱論壇8 D" |3 z! l, \5 U$ ]
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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 % ^( M: A! q F& B# W
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet 5.39.217.77:8898+ p1 t) ?* {: p+ Q/ ^$ |
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
% O: B# l |, J# B5.39.217.77:8898the continental crust, creating magma that drives the volcanic eruptions5.39.217.77:88982 \$ n0 K* Y9 b: g- }' u
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Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano 公仔箱論壇# q* g" H. o0 Y: y6 m, g
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 * w, G2 c) ?5 F$ `' H
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。2 \! O- t4 |9 O" R
as a pyroclastic flow.+ K: B! k/ j1 F9 R7 N
0 b. J! h& o0 x8 R8 ]* L* 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。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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! C1 ^% m. X/ |7 x * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.
3 L$ [$ G: E9 u0 j) }: L9 Y: b D- wtvb now,tvbnow,bttvb * A shockwave from the eruption could have blown a hole in the cloud deck.# M: R/ ~' @( t- z& _
* 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。3 j7 j0 j4 [1 k/ `/ \4 R
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) k" l. F( |# C. V0 N; g2 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。Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
R4 ^( a, |& }1 Z, Q$ 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。It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 whentvb now,tvbnow,bttvb! X8 x. O/ Y i- E9 M9 I
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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% L; A, R L. W& ]" W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.5.39.217.77:8898: U! ?4 |5 m- ~
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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! M+ i, k* T5 E& f- Q9 M
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 Q5 D9 v E3 g1 v
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# o' D$ K1 l7 V
this picture are from forest fires ignited by lava.5.39.217.77:8898' ?! ]- C8 ] H- L i! U/ 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。% r% S* z6 }- i3 b c& y
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 may5.39.217.77:88980 ~ s, d2 I6 c* s6 N0 v$ x
also be the oldest-known active volcano.公仔箱論壇; Y# P8 u; D) Q$ |" c
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# t: U8 a5 k4 H0 |$ 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。
6 l) t. t. V* ~7 U 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。A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high 公仔箱論壇. }9 o' H* ^/ W, x" z
and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.公仔箱論壇7 @0 ~1 V8 u s+ G% ?
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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
! Z3 w& X7 C ~& w7 H0 i4 @5.39.217.77:8898The 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 ' c0 S" I' g6 g; C d2 G4 a8 d# l
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
0 P. v8 p( H, ?" n7 c) V0 oof frequent activity. The plume reached heights of around 30,000 feet.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。: B! s/ ^% t' z B' a
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5 ?# B' `: Y1 ?. I" S5 t5.39.217.77:8898This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the
$ w/ j; w5 V# j; r& }west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.
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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 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。4 n! e' b. z" k1 M- D9 O7 M
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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This image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra tvb now,tvbnow,bttvb) }$ G1 q! D& p7 d" w6 \
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
, z% O x# i& n3 o* S* b+ 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。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
N! S% t( [6 L. y- B1 y j公仔箱論壇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. 5.39.217.77:8898! ^- r5 d- _. f% R7 U8 v
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
) w7 `2 ]9 r0 F1 ^/ ?2 m/ ETVBNOW 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。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,
) Q7 U# C% |, K+ g" X3 b3 Z, ^- ?tvb now,tvbnow,bttvbcausing avalanches of debris into the crater. |