One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic tvb now,tvbnow,bttvb j0 t' N- a4 b2 R; B
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
. y3 r! }" T& S$ C0 V5.39.217.77active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
6 W w7 J+ T& d3 F f* P7 @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。Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
! k! T$ B" T1 K1 s! F$ I" A6 x5.39.217.77erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous 0 M/ z' m$ ?, h. x/ f# W! _9 t6 d
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
, L& S$ X0 C6 i8 z$ k1 r; {5.39.217.77They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.
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5 [ C, A9 S) R5.39.217.77Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above 9 k6 ~& P& p3 ^
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewastvb now,tvbnow,bttvb1 N* Q+ L+ Q. E* n
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash 公仔箱論壇! a/ F* r! v) a( w. T0 K: j9 c
plume reached as high as 50,000 feet.
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Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
7 A3 q* ?2 |- k, k$ _/ Isatellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000 tvb now,tvbnow,bttvb% @9 j/ ~/ c( }5 j( v
years. The island’s jagged edges were created by massive avalanches.
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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
3 g# ]) ~8 d2 Q5 @+ ]1 Aof Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet 5 U5 K; ?% a4 u) ]4 F
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
( X; `+ \7 P+ Gthe continental crust, creating magma that drives the volcanic eruptions
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Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
3 L. i' i) V; s5.39.217.77in 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
; \8 P: ^! T& s5.39.217.77and 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 ! f2 l- L+ p' c: T8 @
as a pyroclastic flow." C* x( `, ]" E7 `/ ]
! |4 z( I0 ]: F# K# f7 s4 w2 _0 TThis photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up:tvb now,tvbnow,bttvb3 |& Z& X/ }8 V& L
# e; [, I3 o8 [6 Ntvb 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.
. `5 ^! R& e+ F' w8 N( J6 M9 c/ P5.39.217.77 * A shockwave from the eruption could have blown a hole in the cloud deck.6 n: |8 |0 g. f
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds." z/ j( _+ f; ~
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" e) j3 a9 k* a- A/ {) ~1 r公仔箱論壇Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet. 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+ `8 |8 J- c
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
& I& H! H7 p, I9 T7 ^# F* g! t the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.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 [1 Q- |* I! d3 ^! n9 p
; C4 w4 m$ j8 c* B* yRedoubt 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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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。$ W1 _- z% v# H1 Q, C* ~
Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes intvb now,tvbnow,bttvb' O! @# P/ r; c0 _# u) v! p& m
the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one 5.39.217.77( J$ V$ M# M7 J
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
. f* s2 R+ [7 @公仔箱論壇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 mayTVBNOW 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 u# j% g2 [0 n; N) g; H9 S1 D
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。' u+ x, i1 [& U8 T- E+ n1 f2 ?, i
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3 y7 l+ H' U3 P6 r/ k, @A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high , E1 ] {- `9 H7 [( m( j
and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.公仔箱論壇0 {3 o7 ?( z" y# f( w1 i V3 Z" N1 R
8 S. j1 @' D/ X/ m9 O+ h8 n 5.39.217.772 O. w4 k; {% x9 \6 \8 i
' Q+ c7 v; }# x2 B: f+ Q: @4 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。Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City. tvb now,tvbnow,bttvb6 i8 i- O% _* m! x8 U
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
/ R. d( T+ I8 M7 O5 y0 emultiple 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
4 }, d |& {( y- E- k5.39.217.77of frequent activity. The plume reached heights of around 30,000 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。. P3 g- }* b4 I, j; _7 g" Y8 b( T
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( M5 C0 b2 B3 M/ I1 _公仔箱論壇This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the 3 D. H( c! s6 n" Z: l
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.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 H% ?* R" b, E
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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
3 ~! X- M. ]# Y. t+ X: _& j5 eflows 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 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 r8 G8 F! c' s; N5 {
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 tvb now,tvbnow,bttvb# h- R0 \/ Q( N: x
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 6 m X a8 v7 X
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.公仔箱論壇+ p8 v4 _- w! F& X
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" ^* ]- C0 c) e7 N- YNASA’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。. P( _9 f( r2 G* B0 E J5 Y8 q6 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
1 L/ h! H s, r( U1 Y+ |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,
) K( q+ w, s0 J V, u6 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。causing avalanches of debris into the crater. |