One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic 8 r- B1 O( I( q5 A, _3 s- H
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 9 F) L: z$ h; `# @2 k* v
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
" t- {* k/ x+ T0 ?( q) k, J5.39.217.77:8898Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens, 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' s" ? O) H6 [1 Q& `
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous * x, i, U* ~/ P8 c4 r
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. # q" I! i9 j; J9 N: X; R, k8 e6 p* q
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.
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Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above
* R" M* g3 H6 C! M& d) \( D$ uof Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas公仔箱論壇$ b% S4 D+ \/ I! A
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
# G! Q* C; X: ^! I% J5 a7 \6 P2 _plume reached as high as 50,000 feet.tvb now,tvbnow,bttvb" X s i: I2 j. ?0 M5 p$ z
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Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
( ^& ?, ~9 s2 y- k$ Y0 ktvb 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
9 ?, c% @2 {) X; E. |( H7 B7 [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。years. The island’s jagged edges were created by massive avalanches./ E9 }& O i4 W8 I2 H4 P
" H# _1 j9 c* o7 Mtvb now,tvbnow,bttvbAugustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring
/ g2 K- X8 W1 K3 Rof Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
$ z& Z( p+ r0 M2 u; b5 `公仔箱論壇ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of 5.39.217.77:8898. p) T; H) ]- j
the continental crust, creating magma that drives the volcanic eruptions' X; q! ]. l) A% o$ n
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7 q: p) q4 O3 v2 \1 V; 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。
2 y; J0 j& N4 x/ V% a* `8 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。Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano : G6 p. n) H7 s1 o- I
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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% y" I( K: h; l8 L0 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。The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising
# s9 P7 \& _! t/ f& k8 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。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。1 v# v6 z+ _$ x5 m) }& F; j
as a pyroclastic flow.5.39.217.77:88989 ^% F9 |2 G; S
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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 m" e( o! \; [ ` m) p: f
5 y4 b1 X* l1 mtvb now,tvbnow,bttvb * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.
% P# k8 P2 q0 W, `0 ?$ b! o9 u& _2 j * A shockwave from the eruption could have blown a hole in the cloud deck.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 [ ]: \6 L8 ?3 U9 C
* 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. . s! o7 Q8 U' }) K' |! g
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when& ^& a: E L, O# w: E
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.公仔箱論壇+ k2 n9 A& R, A8 X, B0 `0 q7 Y5 Q
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+ l- M7 K0 |! j7 N! X$ t5.39.217.77:8898Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in0 l, g( \8 T2 q9 L, 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 公仔箱論壇7 E1 f7 a# Z- U) S2 q. Q8 s& _
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in $ ?# T. q! A7 f3 ?" ^. ]
this picture are from forest fires ignited by lava.tvb now,tvbnow,bttvb, s3 _3 g( I/ x3 Q: C
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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 may0 h3 l6 \ T- o7 E" I
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。" }) F g+ m0 X' N4 u0 T
, S0 i5 U& l" E! H: d8 P0 d & J: U! U J. m) Y# K/ `
: z2 @0 e U- N; u' t: W9 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。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) S5 k/ X, I7 \9 S
and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.5.39.217.77:8898# Y! w2 n5 z# o7 ^3 }0 S3 r
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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
9 U& Y" `* s& H6 D: Z5.39.217.77:8898The 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
% z% Z0 |. U& `: @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 * R2 [( [" N- w' p" `( r) X
of frequent activity. The plume reached heights of around 30,000 feet.
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+ s& K; r" i( |% X' v5.39.217.77:8898This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the
) I* I% {4 _7 O7 E+ s2 I1 }tvb now,tvbnow,bttvbwest coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.) B* O7 |% j a( H1 ]/ j6 Z* l
" c9 X7 x0 a+ v( B; p1 b3 RChaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic
! A$ y# ]: K& B" H$ g# \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
2 Z7 G% c# h9 G* \6 A9 X/ U 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。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- q' O( ]3 {0 x# w$ i
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。, H5 I' S. x# u; S( t
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.5.39.217.77:8898) F& Z8 u9 _3 u( G+ R! u) s3 S
' v) Y; V2 e8 @) E R: M 9 P6 k `8 ?9 D% Y" ?0 _7 e; y
5 r" |4 w* a% i( i& y! a+ HTVBNOW 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. 8 j3 l# T" D7 A" W' P
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 5 d/ z& V/ ~7 v" J$ p, i! @
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, 公仔箱論壇+ ~4 X, E1 |, R
causing avalanches of debris into the crater. |