One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic 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。8 i8 P9 y6 F6 T' w
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
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Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens, www.tvboxnow.com7 k' W+ ^7 C. W7 a2 M; S
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
2 D) f6 }$ P U0 P. @3 A公仔箱論壇and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
8 D; \& {$ g7 B* `公仔箱論壇They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.公仔箱論壇, z3 z+ [( B- |( U* Q$ ~2 b
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3 I8 H6 ^! U+ q7 H jwww.tvboxnow.comMany of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above www.tvboxnow.com7 K3 h% F: s$ O2 Y: [8 b4 x0 m
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewastvb now,tvbnow,bttvb& k y( q4 y; U: x) p+ B+ O& o
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
; K8 @3 h% \2 J V/ h! Wplume reached as high as 50,000 feet.公仔箱論壇. L$ Z: `# e, \ O& ?; b& A
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Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra ; I; X5 @& r: B) j
satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
W; Q. r* S) W8 M. r$ E" Qtvb now,tvbnow,bttvbyears. The island’s jagged edges were created by massive avalanches.
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8 l! x3 C+ z" }2 A0 f) G& TAugustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring tvb now,tvbnow,bttvb; O. r2 k- c1 F" e1 j
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
, g5 e; t8 S2 }1 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。ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
1 [8 @# Z: ], b, T) G) g7 D' l1 N公仔箱論壇the continental crust, creating magma that drives the volcanic eruptionswww.tvboxnow.com8 A2 A0 j8 q J A
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Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
6 `4 f' ], f$ B; R* m" G0 h公仔箱論壇in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.www.tvboxnow.com3 C6 X# w; p2 o9 m: o& a
; p. e6 R$ _! ]! {& q/ _www.tvboxnow.comThe 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。 X) e. ^/ D3 S) S E
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 公仔箱論壇 [0 w' z# ]* K M& S- H
as a pyroclastic flow.! o# `1 Q8 N* ?! ~9 h9 A
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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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9 B8 M# n6 @7 x$ r8 s6 U公仔箱論壇 * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.
1 P5 {0 @( c/ }( \ * A shockwave from the eruption could have blown a hole in the cloud deck.$ d/ N5 o* | ^# n
* 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.
3 g0 q2 z4 c" B5 T公仔箱論壇It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 whenTVBNOW 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 Z% S8 Q2 H7 `! |' }
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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* a7 a3 ?& i' \ Y7 ^0 PRedoubt is a 10,200-foot tall stratovolcano 100 miles southwest of Anchorage in the Aleutian Range, west of the Cook Inlet.% M( Y+ l3 }0 K1 w) g0 |* [
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; y0 \8 N I8 u; O+ {4 `Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
p% i1 L2 P, J- ]1 { 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 R( ~' E2 R' v s6 P) R% K! D$ |
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
: |. ~% Y, K; i9 {) lthis picture are from forest fires ignited by lava.
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: o' X8 n T! t) {. X( t4 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。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 F: C) Y$ [+ @% w
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 tvb now,tvbnow,bttvb. m. l8 N( }$ p' D4 P7 c5 \
and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.) g9 C" Z% J( ]# P( P9 M! l% y
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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City. 0 s# M' U3 v, J2 }- w6 K4 W
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 4 @8 w5 h5 g2 [0 c1 I) ]
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 " ]/ A0 A+ D/ `" J+ K* n5 g& U
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 tvb now,tvbnow,bttvb# v4 _7 Z0 Z1 ?' o
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.www.tvboxnow.com, r/ l: {0 x9 I3 T6 U9 I
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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
0 j3 ?, k P# l* G* Lwww.tvboxnow.comflows 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." W2 B6 ]. W! ~' e
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" L, E$ x* y6 {$ t9 N' |! Mwww.tvboxnow.comThis image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra
* H/ k3 {+ B7 p6 O/ Kwww.tvboxnow.comis 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
) u1 a0 y1 C! ?. n. i" }! A; ^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。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
) W3 E; J! \: p; M6 dtvb now,tvbnow,bttvbstationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.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 p& l X1 p4 j7 K
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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. 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: a$ z0 d1 c, e4 \2 a/ c. }
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
& z( g& ^7 K# o5 J7 H公仔箱論壇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,
# z2 i T, _- M) o3 \2 Bwww.tvboxnow.comcausing avalanches of debris into the crater. |