One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
& q# j6 a+ m/ Neruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are tvb now,tvbnow,bttvb: L2 M2 G$ o* _" p9 ?' |" i
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.5.39.217.779 u8 m& E! u. S# w1 X$ L7 \+ l
Some 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。! t7 |* @* y# _6 l3 u1 |' Q) k
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous 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。# b# ~3 r3 M& d$ o3 l+ |) y, b3 ?1 ^
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. 2 s+ ]$ l! e5 C( f4 p9 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 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。- D8 ]0 @ X$ j- Q4 b1 r/ d B
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewasTVBNOW 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 [/ v1 i" ?
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
( }6 n3 }+ E/ G# J% _* P$ Q( k5.39.217.77plume reached as high as 50,000 feet.
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$ G, R+ [: C1 k& A4 [: ?1 ~Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
" p6 E1 d( l2 i& K5 K( z公仔箱論壇satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
( F7 n# x! ]! T2 RTVBNOW 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.tvb now,tvbnow,bttvb1 }- x# U& ^( h5 Q! s* L5 N5 F
: d. X9 f0 C5 c. D* t7 q' ]- HAugustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring
0 E& b1 D( U8 U3 c公仔箱論壇of 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。, d: h; y( O J2 O( I
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5 A& C0 v. d' V9 F6 D; |9 n/ i
the continental crust, creating magma that drives the volcanic eruptionsTVBNOW 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 {+ Z3 ?2 j+ ]2 T
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4 x, n$ d$ I* ?8 W, W6 K公仔箱論壇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。, u4 d! f! m) h1 Q5 A- K
Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
, p9 y# P2 s Y# Q) ITVBNOW 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。in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.公仔箱論壇/ b# m1 O; H+ J+ `2 a ^
6 g! E2 R$ ] |! pTVBNOW 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 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。3 _* `9 l9 Z/ B. R! i3 Z
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。' V; Y; U5 X, Z( N6 B/ X
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:
5 q& S: \5 C6 f2 z: ^8 fTVBNOW 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。
# B' Y$ c- `, I * 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 n. ^0 l7 L0 }) d& F8 pTVBNOW 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 shockwave from the eruption could have blown a hole in the cloud deck.
N) w: V: U+ L5 r公仔箱論壇 * As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.
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5 ^, l, z4 w8 |4 lAlaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
5 |2 J! U# {7 E' k* 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。It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
( r& F7 ]" G9 x% Y6 a公仔箱論壇 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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9 N0 n9 ]* K% f: h* }( kRedoubt 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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5 l6 ]5 N9 L; Z2 `Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in5.39.217.775 u6 j, a5 ]% y* v
the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one
. i% t0 d, t, | ^0 q8 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
% W4 w2 S( {" \3 b6 J9 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。this picture are from forest fires ignited by lava.
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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公仔箱論壇5 @# x; b6 z( |9 d. M1 A0 ^
also be the oldest-known active volcano.
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* ?+ F M# k( D& G3 W6 R# @A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high ' s! { `3 n4 B8 n6 M
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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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
2 y0 B5 H8 R% d& D4 }5.39.217.77The 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,bttvb' o( g+ k6 N! f( i z
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 5.39.217.77. n5 V! N' N) W: I/ E
of frequent activity. The plume reached heights of around 30,000 feet.: d, a$ S2 J3 T0 g$ l2 e% P9 z
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This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the
: N7 @1 K4 e* f* V* ~公仔箱論壇west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.5.39.217.771 r3 r' {' `& Z
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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" w o5 o' ~+ P" f# x, c
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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! @: q- M. [% P9 G+ IThis image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra 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。$ \0 Z' C A* R6 q' S( E
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
0 R3 Q7 R" _7 `6 Q- W! Z4 o* U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 公仔箱論壇# p N5 S. D9 Q9 ?# p
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.
4 q5 k& i* j- f; x$ U. t) Y7 o公仔箱論壇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 S$ T) x7 B8 E/ u# n+ |4 \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,
* Q5 X" Q! o$ m" E1 ^tvb now,tvbnow,bttvbcausing avalanches of debris into the crater. |