One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
- k: w- A; ]: VTVBNOW 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。eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
0 E0 g, N8 e! d5 cactive each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.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 b. V9 S+ ?3 N" `
Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens, 公仔箱論壇( _! M: A8 h7 h8 U
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
: X! n/ m- j; @; D1 Z4 mand explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. 6 D; Q6 e9 a" w! X' [" g
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。& `3 E7 m0 s2 f% |8 a4 @
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v* ^( {& D- d* W( YMany of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above
/ T& z3 B) K5 @/ ?" J% d# wof Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
R" `$ P: w$ g! I7 gtvb now,tvbnow,bttvbtaken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
' u* I: N7 W6 s, \& r0 P- A( Eos.tvboxnow.complume reached as high as 50,000 feet./ }/ T2 y6 r: U0 o4 k; g8 u( V
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Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
" q# |$ E! t8 E$ j4 o7 M3 W% osatellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
+ z( a& {/ {4 i! D公仔箱論壇years. The island’s jagged edges were created by massive avalanches.8 k7 W; [% A) L) H
4 @4 Z& O/ m( f; N5 {公仔箱論壇Augustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring 6 n0 ^$ q! z& n* z% a7 ?
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
7 A4 U( r2 j6 A: X" r( Focean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
9 K: E2 ?0 [7 c5 B2 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。the 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 tvb now,tvbnow,bttvb0 F" r; Z1 \" z
in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.os.tvboxnow.com/ H, F: N2 ?+ a' X5 j- [+ a1 t4 ]
2 }. g* b- r. j) }8 j9 tTVBNOW 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 公仔箱論壇5 J! I3 x. Z5 s3 ?! H9 ^
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
9 M0 b* Y; s5 m" C3 @; u公仔箱論壇as a pyroclastic flow.
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* X$ k. D) x0 m0 q' c6 u% R4 s! M* hThis photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up:+ H7 I( W* |& {5 `- O8 y6 d
/ f" l- P! a5 f * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.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 X R2 O, i6 d5 [
* A shockwave from the eruption could have blown a hole in the cloud deck.tvb now,tvbnow,bttvb" {" v5 {* d( o4 o" E0 y) {
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.
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, u% X. E1 Q( {Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
. X. C* D# W* H5 ^& _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。' i) L8 h8 k+ R
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。' }+ A h9 J* i! z; }, x$ a8 s0 g, N1 t
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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.os.tvboxnow.com, |' o2 y9 S8 P \% Z' W
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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
8 S- _5 t9 f. M$ N the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one
/ V( I8 O+ w$ o* [' Jos.tvboxnow.comcaptured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in 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。# y8 S0 ^8 i1 @3 s$ N {) v
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。8 f" c5 I2 V% \2 n
also be the oldest-known active volcano.7 H$ M6 f Z1 n$ s, ?
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6 F# V# K' G6 u) h7 F2 e+ \8 Y' w/ l3 mTVBNOW 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 NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high
0 L. ~3 D1 o7 r" t1 j* u5 B! 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。and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.tvb now,tvbnow,bttvb! Y' M o5 r% M) b8 S% U5 a
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8 O1 V( E" k* I! V# PPopoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
; q! k) h, X. m d9 ?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。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 z) G1 a( y" I& b4 |; A# ptvb now,tvbnow,bttvbmultiple 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,bttvb2 F# R; |' P) f7 e
of 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。' M) h' e% {; o$ w& s0 _
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! p4 y3 {- _7 c+ t8 H2 o q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
4 B5 [$ V) h$ B4 q& L# z$ Qos.tvboxnow.comwest coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.
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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( m1 b- w0 a- X
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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This image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra
7 a2 W1 I/ p1 S2 E2 A, ]1 ]( e公仔箱論壇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
' e' Z5 ~( n" b. ytvb 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 0 Y$ [9 _+ X6 j W4 N `5 k8 n
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.公仔箱論壇6 e3 n' t6 Z8 ^! j& C
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% @& Z: A9 `& b$ t. q, ]: iNASA’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.
$ M# a: u3 } V3 Zos.tvboxnow.comA 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 tvb now,tvbnow,bttvb' @( e) U- ^; W7 U: d
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, tvb now,tvbnow,bttvb! L- W& e3 W2 ~1 U5 Z
causing avalanches of debris into the crater. |