One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic 公仔箱論壇# j/ u/ C6 n' I# v
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 公仔箱論壇) x( |" a! `& O& q4 [1 r( Z
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
) H- h. c2 q f6 t1 A公仔箱論壇Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
' @2 r1 D: f3 V; W# t% ^os.tvboxnow.comerupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous ( @9 y' ]5 U1 h! p$ z S* A
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. os.tvboxnow.com+ ^- [" y* M& H/ t( v/ D$ P
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.7 J& a$ |4 q+ |% L4 f. q" d
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% L& W, l) w6 s- N1 [! y/ _tvb now,tvbnow,bttvb
$ r* \6 C y7 g9 W4 [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。Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above 公仔箱論壇; q0 ~. R5 y& ]* j& I
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
4 C7 s3 Z4 |4 F: F# O) c- Q& d9 Cos.tvboxnow.comtaken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
0 \6 [# g7 Q& @7 p o8 r+ iplume reached as high as 50,000 feet., Z: o: M. L% a
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' Y' Q/ w9 ^' m s公仔箱論壇Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra 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 y! d0 F/ t2 b- M% P% `/ T8 G
satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
- X5 I9 Z% b% r6 gtvb now,tvbnow,bttvbyears. The island’s jagged edges were created by massive avalanches.9 j0 ]+ _5 o7 r- P+ O" g* w
& [$ t8 @# r+ g' @4 Atvb now,tvbnow,bttvbAugustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring , w1 e0 k( `; ?& l( x& O0 g% H7 T# W
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
9 Y0 Z8 E5 d* I7 t( x: w! xocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
+ w' j4 r6 s: Q8 [1 M" }% o公仔箱論壇the continental crust, creating magma that drives the volcanic eruptions
' M/ T, [$ n9 [) |; j/ Y* @1 |- 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。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。& F/ c* ]8 Q( z4 a) J1 A

& w+ `; {2 H7 L) j" r$ p1 d% `. O- Z
& }- Q4 X% }: 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。Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
2 d; ~5 Z' ]! }8 O9 V9 p0 O0 Fin the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.
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8 u) u! L* Y' H2 J2 X; g! V) tThe smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising 0 _' r l$ t) Q0 J2 B9 T8 F& J
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 tvb now,tvbnow,bttvb9 }0 `+ o; @3 I
as a pyroclastic flow.tvb now,tvbnow,bttvb0 [& f5 r* x' Z% C5 b* j& [
% o; s5 P; h j' J* m' @公仔箱論壇This photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up: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。6 v) E2 J- ?5 v% s% Y
( x( O+ d! o# B) I, C * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.( d" O1 {- m$ K$ E) h
* A shockwave from the eruption could have blown a hole in the cloud deck.公仔箱論壇2 R& Z% b# y+ U# Z! _# v5 e+ r
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds. E5 ]3 L! @, j2 V6 G8 Z. D; m) r
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$ `; ?5 y- Z* E* H4 Dos.tvboxnow.comAlaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
5 m, W M$ i% i8 L( a: F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 when" t& r' J2 s" {5 V. |9 U- L
the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow./ B H: J. T& `" K& Y; k% z/ F
& @ Q; m( F# W8 m& _& m$ [公仔箱論壇Redoubt 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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+ a! M% E/ ?" O) @$ [. g- _) \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。
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" N& ^! F5 J+ N: D/ }6 ]os.tvboxnow.comMount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
* D+ ]! z8 ~0 B% N9 W0 uos.tvboxnow.com the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one
2 I6 ^; _* k+ Q; a1 K1 Ucaptured 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% q5 g' V$ W0 _2 o
this picture are from forest fires ignited by lava.os.tvboxnow.com: u( l. H+ s1 N6 {
6 s$ `4 R& J, I6 |5 c# B0 Itvb now,tvbnow,bttvbEtna 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 may1 P/ q* C2 J6 w# p
also be the oldest-known active volcano.
; |# K8 v7 s5 L6 \# V( d% s/ los.tvboxnow.comos.tvboxnow.com' C0 c2 k5 P1 I" x% a* G! {0 p
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3 b; m" B0 w/ VA NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high
: K8 G& M- `, {9 ]' M, p% W5 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。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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9 A3 Y; ?4 l" \3 v7 j! 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。* ?; O/ b, z0 A! t
Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
3 a5 }0 v1 b+ J( f# bos.tvboxnow.comThe 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 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( Y1 c l j$ c" i+ 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 tvb now,tvbnow,bttvb8 B0 m: q) x0 `) d* y8 E+ q/ o5 ^
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
- T( \) h; }/ 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。west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.
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# G$ J0 S! x2 N1 G$ }6 W7 f公仔箱論壇Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic 6 y+ f& p; a1 I# @; \( z
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.公仔箱論壇# s4 s; } S' i5 J- Y5 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
+ t* L4 w' ]; O) w& w( ?$ rtvb now,tvbnow,bttvbis 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
9 [' r- O4 E3 |. M' A& R0 T, Etvb 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 3 B" ?( V& [" U5 @' U2 M8 d
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. tvb now,tvbnow,bttvb) l$ B$ {0 b( }8 @( W
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
% k6 }1 B! E5 r2 i- ^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, 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。6 \$ j) f% j' M$ X
causing avalanches of debris into the crater. |