One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
8 y7 r T# w+ r F/ t1 d: o) H1 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。eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
- v( i4 } R. P$ B) H1 K# @active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
. l6 g- p. ~1 \$ H$ J: c% cSome volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
/ X) }8 H$ F* @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
- J8 f4 \( E8 Z# K8 _and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
/ N) C1 c1 _" D' cThey tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.公仔箱論壇8 Z: t6 e( o0 [ {9 C/ F% C( A( ~
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Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above * C" r' `" B8 h
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas! i4 `5 R$ w- x- g: k+ c
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash 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。9 Z7 {- V( `% b# p9 O0 t
plume reached as high as 50,000 feet.
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! z5 ~/ T# j1 O. zAugustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
8 x* O& K) 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
- X! B# y4 z9 s5 i5.39.217.76years. 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 2 l7 E! h" n* Z. |2 [9 ^
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
6 `+ E: a, j5 n. t+ n+ ~8 [5 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。ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of 公仔箱論壇2 Y) t7 h! ~- f' r
the 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 7 S* }0 l2 o4 n* I+ J$ B
in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.
8 \( T3 }. a2 i% w% D公仔箱論壇tvb now,tvbnow,bttvb2 E7 {: N: ?. s; N* `
The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising 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 i+ z% y' I. Z- M# T
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 5.39.217.76, W! H8 |6 _8 k2 c9 T' H
as a pyroclastic flow.
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- Y1 N' g6 _) ^. a: Utvb 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:
: F! C% h% Y& z3 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。
. ?6 q ]8 Z/ U/ S' }" c- t5.39.217.76 * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.5.39.217.76# |9 T, B2 W1 r+ f
* A shockwave from the eruption could have blown a hole in the cloud deck.公仔箱論壇& X* e* B& Y. M+ A8 H8 O
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.
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Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet. . u M% o7 A, W j
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when公仔箱論壇; i# _) O" e) W! g
the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.+ l8 |" J* \2 G. a# V) m
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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.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。% q& w) {. ?( D
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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
! r5 n) r0 L1 |; U the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one
( k. s, V2 \8 v4 P; B$ Ptvb now,tvbnow,bttvbcaptured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
" c/ l. g: y. l* W* u# Pthis picture are from forest fires ignited by lava.3 s7 x( [; t, K) [ g
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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
. T1 @5 L0 H9 p6 A1 a" j8 M5.39.217.76also be the oldest-known active volcano.$ g ]4 m5 q9 o' o, R2 L3 W
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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
+ n7 X5 t; B8 v3 Tand 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。, c& p9 Y. N5 ~; V
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! {) u: R" X/ k1 _4 f公仔箱論壇Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
6 h9 o: n, u0 B/ NThe 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 5.39.217.76* @) w; z# y/ I7 l! ]* m
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 5.39.217.768 k/ t4 }! H7 O) _& s
of frequent activity. The plume reached heights of around 30,000 feet.
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This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the 5.39.217.76; z( W! h1 d4 S9 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 tvb now,tvbnow,bttvb( G5 @/ S: {$ _* z" d9 Q7 D. N1 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.
( I1 C3 ]# r" h5 h& w( w- B0 QTVBNOW 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。5.39.217.76; M" n* F7 @. `+ w
. i5 v' f8 K! j! I8 ?+ _8 b9 f0 @
% _1 f6 _$ V+ ~% ^" JTVBNOW 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 tvb now,tvbnow,bttvb' q3 v$ U) o; v5 [8 D1 F
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 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。) o! u5 p+ j9 T
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
1 W# T8 |: `) _' o: H8 [5.39.217.76stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
. y5 s/ G/ c6 Q! |- ]7 jTVBNOW 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。4 J: b5 p/ `% {8 C7 J
5.39.217.769 l$ n0 V: W7 i% f6 j* h
! r) Y6 f# \( K: O8 D9 o% 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。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. 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。: U: d5 ?0 L3 {5 }2 w6 _ p s9 g/ e
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
8 g f$ Q2 F! D$ q5 P$ n4 ?& ?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,
+ r+ V9 O d8 u( |' z; l+ ^$ ctvb now,tvbnow,bttvbcausing avalanches of debris into the crater. |