One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
- U$ y* M" b# H6 GTVBNOW 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
) ?% w/ j/ Y, F+ M3 e4 atvb now,tvbnow,bttvbactive each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.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。% V, p2 [/ I- N% ]
Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
- Y' O$ L8 g- g. V8 M7 H: W公仔箱論壇erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
8 T7 Z: ~7 z3 d' `: j9 h4 P" z( cwww3.tvboxnow.comand explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
3 d# z5 T% i: U- p! V# p& aTVBNOW 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。They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.
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4 B) B$ {2 e ^; Z8 Y公仔箱論壇Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above
+ F% f6 s" v6 a- u% V公仔箱論壇of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
0 {! `3 h; f9 }2 q, \, 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。taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
$ ]/ h M8 M9 K2 P, Utvb now,tvbnow,bttvbplume reached as high as 50,000 feet.tvb now,tvbnow,bttvb! s% N' j) w+ A- X% Y0 L& q
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Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
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years. The island’s jagged edges were created by massive avalanches.www3.tvboxnow.com: g" ^/ m; _, |2 U4 ]0 z0 j9 F
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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
( y4 u$ H* V1 u2 l. \& n, Rtvb now,tvbnow,bttvbof Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet www3.tvboxnow.com: j/ j7 {0 @1 p- H6 a y1 U. b
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of tvb now,tvbnow,bttvb+ ^: Q5 q! N0 X7 M' E- e
the continental crust, creating magma that drives the volcanic eruptions$ V' J+ x5 `* X6 _( g" P5 I
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' A, P! C+ L0 b) J公仔箱論壇Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
4 t$ t. p1 e" [: |/ ]7 O" ain the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.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 q4 t9 i Q9 u+ O" ?- S
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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
- ]! i; q. S) M3 X* wand 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 tvb now,tvbnow,bttvb% w' [& S4 ]0 }: ^+ u
as a pyroclastic flow.www3.tvboxnow.com6 n( B: ?' n# C8 z
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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:
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2 Z7 Z9 l7 P3 m1 e1 u * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.
6 V3 X8 N. l$ R1 G5 r, S * A shockwave from the eruption could have blown a hole in the cloud deck.9 t l$ j; s, F/ h$ `3 `1 R1 p+ A
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.公仔箱論壇/ G0 y8 \6 r/ F; n1 p8 [
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Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
) v. F/ P$ A6 R, n9 {It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 whenwww3.tvboxnow.com. }+ ]" a% G7 ?8 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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6 P$ S/ Z4 B$ c* H- F" v& S3 L3 `tvb now,tvbnow,bttvbRedoubt 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
# g" n! n/ x& A" u! g% t# r6 Z/ @. R公仔箱論壇 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 m V: y% V% l) L公仔箱論壇captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
% K+ _9 T* X4 g2 B7 I A# ttvb now,tvbnow,bttvbthis picture are from forest fires ignited by lava.公仔箱論壇9 ~ S% [$ h* ^9 w2 n" X
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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
: _" q& B" [ w6 X6 vwww3.tvboxnow.comalso be the oldest-known active volcano.
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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 " c7 j( j$ P+ u h- d& a" e
and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.
8 U; N. U S% C9 X- v1 a8 k" r: 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。$ Q9 @# d& L( \1 s- i# ]3 t

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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
5 L2 I# t- x; Gwww3.tvboxnow.comThe 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
+ K, H3 w% Y+ B8 q1 r ^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。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 tvb now,tvbnow,bttvb+ a$ E% S3 [9 O+ j
of frequent activity. The plume reached heights of around 30,000 feet.1 v5 k! ` ?& H( L
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This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the $ N. `9 R U6 N
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 公仔箱論壇3 ]5 j% T! Z2 V; l' O
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
1 w# c f' ` r' [& f& T" T2 Yis 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
0 w; ?6 }) S* S. K5 z5 M公仔箱論壇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 tvb now,tvbnow,bttvb$ G1 H: n8 i' F* P& y1 o% Y# ~
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. 公仔箱論壇: f7 ]) P8 S% W6 S0 Z0 G* t- R
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
/ h* o0 z. `! L0 jtvb now,tvbnow,bttvbthat 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, 公仔箱論壇: w8 Z2 w2 v+ @5 X0 V6 y: _$ p! F
causing avalanches of debris into the crater. |