One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic 公仔箱論壇4 k, |+ x% b* C! E% c8 k0 _* c
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 公仔箱論壇# d' W2 c) @; X4 i4 x' _" ?
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
4 @* F+ g% r7 C1 d- Hos.tvboxnow.comSome volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
6 k1 Z( V7 B+ O# C- z `! dtvb now,tvbnow,bttvberupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
1 R+ i n/ p0 ^: }+ mtvb 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。# R! i$ A2 B7 b I& ^0 |
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
+ p' y- _$ F1 y: e6 F6 OTVBNOW 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。of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas公仔箱論壇# S4 x/ @; w9 |' |0 F0 ]1 ~
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash . v& l# k* q4 a8 C! b
plume reached as high as 50,000 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。& z$ ^$ T ^/ Q8 [, U
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! `2 B) V _& G" z/ K5 OAugustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
; f' Z. `1 V; p6 jtvb 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
$ N& N7 K) v( n4 L5 @; Q! d4 Bos.tvboxnow.comyears. The island’s jagged edges were created by massive avalanches.
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# Z M" r, A- ?4 {, q" c0 `& NAugustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring
; a9 T; j6 x A! \# m5 e0 ]( Yos.tvboxnow.comof Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet 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 B( j/ E3 Q6 I; ^2 g8 ?
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。2 n* ^4 j( @ r! n
the continental crust, creating magma that drives the volcanic eruptions4 {! B- ]0 ?% N. h
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2 Q* N: Q$ R6 j5 }# r# U) 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。! `1 i- y/ H$ J5 V* Y. g
Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
' C2 F* Y! x: E' O" K7 Ain 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
( t1 X3 B9 z* {# u: V0 Uand 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
! x) a# W, }; e5 F: c/ `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。as a pyroclastic flow.
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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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1 g4 E5 b* j/ g * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.8 O9 e5 I0 `) m
* A shockwave from the eruption could have blown a hole in the cloud deck.
' Y% b4 B# e8 b% n* V2 [4 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。 * As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.os.tvboxnow.com8 I. w3 H: y( L- W( Q% b' N# i
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Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
X! d& }0 ^! zos.tvboxnow.comIt continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
; F( Z7 P5 r# z2 Ttvb 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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3 Q) D, j% i, d" S* q8 Y! Bos.tvboxnow.comRedoubt is a 10,200-foot tall stratovolcano 100 miles southwest of Anchorage in the Aleutian Range, west of the Cook Inlet.tvb now,tvbnow,bttvb) o ?# c8 D) @) R
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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
8 C. {1 e" ]9 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。 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% Y$ T4 l3 I7 a) E
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in os.tvboxnow.com$ S0 v* m& i# |
this picture are from forest fires ignited by lava.公仔箱論壇4 {9 p J: {1 `' X$ Y
7 F1 H% f- `/ VEtna 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$ Z7 u3 U$ }6 d& C+ j% N) c
also 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 / H( u+ R8 {& m* f+ h* L! D
and 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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8 j0 J) ~# i7 c1 @+ e2 Jos.tvboxnow.com os.tvboxnow.com# p/ F. O' p# t8 ^- ~% ]2 w3 v, L$ |
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。; m" Q6 L: J# U+ U `
Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
, X# i% z% k- U! W9 ~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。The 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 tvb now,tvbnow,bttvb0 ^( c2 Q+ T+ W
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 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- v' Q" {& p' }& f
of frequent activity. The plume reached heights of around 30,000 feet.os.tvboxnow.com2 `5 [/ Q' b: p, p' Z; i) I
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3 V& R* _9 m8 L5 x. o( wThis eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the 公仔箱論壇! P7 [4 H% c( R8 w
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.os.tvboxnow.com O2 x5 p1 @& x" Y/ A% Z2 q
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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
; V# m, ^- i& bflows 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.os.tvboxnow.com$ K. e {* x/ @
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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
! Z# M' f0 X% M$ }9 jis 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
: v/ p" Y* c* J8 t- ^tvb now,tvbnow,bttvbformed 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 9 y: ^- s: W v" R) {
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.公仔箱論壇. ^7 ^5 k" h0 Q. b; d
! `& f& m8 f# J% b, u$ Utvb now,tvbnow,bttvb 公仔箱論壇, b2 W; p& ]; N3 n/ h, U+ }1 s& K
) S- V( H% h% N* [5 v. 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。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 o6 v# S5 b0 V5 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
! t5 O2 [ R. S8 [$ Pos.tvboxnow.comthat 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,
, k# R3 t7 A( X& V/ |7 i G4 F% Wos.tvboxnow.comcausing avalanches of debris into the crater. |