One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic % O; b0 ^+ g* |7 f* G# L$ `
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 5.39.217.76, }2 R/ z# h+ R/ e
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.% S: ]2 I) m0 B$ v
Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
9 @0 S# C$ G4 G; ^1 e6 q: [ ]公仔箱論壇erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous 公仔箱論壇! N$ F1 V/ \8 i( J1 V$ D8 S: U
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
: p, r. Q& b& k* E ^( c% 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。They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.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。 D9 B" T6 h2 g l' h' [
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8 E- e2 f2 b. h2 A( P% G4 W公仔箱論壇Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above 公仔箱論壇) t, W$ A2 n; |8 }4 p1 O
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。9 \* {, B8 c' d N4 ~) g. Q1 I
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash 5.39.217.762 b' o& J0 Q% J1 G6 t
plume reached as high as 50,000 feet.8 }8 @8 v, X* ]+ C7 B" Y; f% B
: @$ ^9 v5 |5 j6 v- u t# t7 }! b* 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。 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 G7 n0 k; f4 n1 q( v6 h9 q
* R7 |' ]; h( r: k- z% }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。Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra 公仔箱論壇% m* J4 [: h) s4 P* I" j
satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
& g7 L2 \7 I* H8 Z& C2 E+ ^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
5 H$ b; n* U$ x% N$ R7 Jof 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。) H; J7 K" ?/ u, p9 F
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
. U! [8 V7 }7 ?( l; y- a) Lthe continental crust, creating magma that drives the volcanic eruptions
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/ s' t+ I" x" u+ O! O2 H6 }& d公仔箱論壇Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
" m) H' y3 m4 C- s% Q3 d4 q- Pin 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 公仔箱論壇: ]0 ^; J/ X; b! `( u) 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
- E$ L+ l6 V, f% |tvb now,tvbnow,bttvbas a pyroclastic flow.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 {& C9 C e, w6 u/ d% h
5 O) ?' \4 I8 w1 W. y! M5.39.217.76This 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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! Y* ?3 t4 Y0 D( Q+ ]6 n Wtvb 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.
6 \. c2 B8 @& V" j1 C8 s& 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。 * A shockwave from the eruption could have blown a hole in the cloud deck.
# R: s, g5 I* P$ y5.39.217.76 * As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.
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0 f( d+ y/ m4 E( q- MAlaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet. tvb now,tvbnow,bttvb, [8 @ {: Z( G7 m$ R' G
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when公仔箱論壇: x! z/ q4 j R( Q, \3 ~9 z6 `, Q
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.
1 |3 W6 v& S1 P& }. v! B0 G% M6 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。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 w' T+ R: m; P: P# e& ]

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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
& [0 m8 q( C# X* j( X6 k# C5 Btvb now,tvbnow,bttvb the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one
& O( o: _2 a2 l; a; bcaptured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
) Z2 ?5 d+ J- r1 F1 q5.39.217.76this picture are from forest fires ignited by lava.5.39.217.76: w1 g! ^' Y s, W! h( A
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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
- Q1 G5 Y3 H- r7 @' a+ r8 gtvb now,tvbnow,bttvbalso 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
6 O e. Z; x3 m7 Eand 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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( S1 s- a- z+ |1 u5.39.217.76Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City. $ S$ S% g# \# U! J8 j
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
; \' f4 A! s3 u4 t) X5.39.217.76multiple 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
& Z. c% }& i% d1 `0 }1 I7 Utvb now,tvbnow,bttvbof frequent activity. The plume reached heights of around 30,000 feet.4 Z8 l& P% t; P! r7 k* e9 E
* A1 i; g$ v$ S/ L5.39.217.76 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。& @! D1 Q! X2 C; A
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6 }: S/ U. S- gThis eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the
7 M5 E; `& v c. D5 }, b5.39.217.76west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.1 [, C& [1 x: Z D s0 _! L6 y
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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 公仔箱論壇. }8 c" k# I1 V) p
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.
# ]2 L/ s! }3 q- ]4 z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。' S! p( b w/ w: f
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7 c9 ~3 p K2 l$ b% \6 \9 R1 gTVBNOW 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 image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra 4 K/ {& {2 E& S) k/ Y6 X
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
) T# h6 \( @) U1 [# ~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
# R, A$ R* w$ z* ?1 Y% E公仔箱論壇stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.tvb now,tvbnow,bttvb7 M. \. o4 T$ M, d
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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.
. _+ x% N) ^* ^( d, A" J3 UA 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
/ c, t0 T6 Y. }+ @7 b( V) V t/ p( Etvb now,tvbnow,bttvbthat 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,
1 X* b3 @, g# a/ l8 _5.39.217.76causing avalanches of debris into the crater. |