One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
' w I, y* Q3 v公仔箱論壇eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are tvb now,tvbnow,bttvb: R! W& }# I3 v5 {' N
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.( t- U* I: B+ Z$ f# f4 |
Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens, 8 R, M6 j1 a+ d& l: a) r7 }5 W
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous tvboxnow.com! G7 `. ^' ^2 `: `) P
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
5 {! u7 F0 h7 ^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 9 i" x, z- o5 T6 Y# r2 B( T2 x8 H
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas公仔箱論壇$ v/ p9 z8 r4 {4 Y
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
$ g- V* a& [; n; f& j& g8 zplume 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 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) h6 }. F( }( p) Q v" x
satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
" C3 _# D5 D1 _; l x. l' L/ CTVBNOW 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.
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+ u* ]/ @$ l* i. SAugustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring
+ D; ^* \9 z# D5 ^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。of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet 公仔箱論壇( Y( ~; I8 `; o4 u$ Y
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
! _& V+ c$ p' [8 b/ r9 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 continental crust, creating magma that drives the volcanic eruptions
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( ?+ @2 ~7 e0 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。
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" P, p& ?5 H3 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。Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
; x5 E% t* i: E% e6 ?! E- Iin the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.tvboxnow.com/ A9 q2 f+ {# ~( f& W" k$ n
5 f. o8 G1 t& U0 v" LTVBNOW 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 tvb now,tvbnow,bttvb/ V* s4 W/ O( F* u: W# 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
# T% h3 z1 D. Kas a pyroclastic flow.公仔箱論壇- P4 c9 y% [% Y3 x" i
& K! ~ K0 ~3 W Q% etvb now,tvbnow,bttvbThis photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up:7 g" t) m1 _3 J% i( Y7 r
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* 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。) H- |5 D, f( U7 C2 N, o
* A shockwave from the eruption could have blown a hole in the cloud deck.tvboxnow.com9 n* Q9 g0 I7 U% A0 ]
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.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。8 u; D4 _ _( P' b: [. V
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Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet. ) w# k& X& l0 u
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when8 V. {& T# y3 Y& j& L
the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.- e R; w- q; \3 c% h( |
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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.
& t5 K5 Y! ~0 Q' K- l! _# |/ q: C2 N* W* d+ l1 `* l5 Z
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4 B9 E" i+ Q9 }0 s. W3 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。Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
8 P( V0 J+ b) ^# stvboxnow.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
' z I4 F: X' B7 h3 ]+ Mcaptured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in 公仔箱論壇" W8 j( d: i+ k" `- o; t2 g* ]
this picture are from forest fires ignited by lava.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 [6 q) A D5 z5 f+ r' w
) B9 q- h ~6 w$ q) Rtvb 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 may
& a" V6 N# ?( R! a4 O% }' H/ [6 Talso be the oldest-known active volcano.4 H( d: _1 o1 X. m3 L2 O4 d% c
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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。 {: u: a+ q; J; e5 G
4 M r# }& Z6 \! ~3 d7 ktvb now,tvbnow,bttvbA NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high 公仔箱論壇, d) p0 A3 @; \$ Y6 f3 s
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. tvb now,tvbnow,bttvb4 Q" g; L3 T1 T% Z4 A
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 tvb now,tvbnow,bttvb2 L2 Z2 R# F# ~2 B( Z% a* I7 H
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 公仔箱論壇! g" Z% \ a0 {+ u
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
# n9 j$ t4 O9 ~% U. p; Htvboxnow.comwest coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.$ b/ E* c$ Q1 ?; e
1 I( @4 O/ S4 P5 c5 y* P, H! ]! ztvboxnow.comChaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic
/ ?( `: v3 W l+ tflows 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
( y s( Y- ^: q9 R, f* {tvb 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
" J1 o; @( [4 i+ D" c% `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
% `$ z2 M, Z% x% \" 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。stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
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! E3 r& ~! r, Dtvboxnow.comNASA’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. 公仔箱論壇8 P/ n6 ~. q8 f1 v$ b0 N
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
. h+ U0 ]- R) Y' ]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, 公仔箱論壇4 a; m9 s* A, D, r0 A8 N; E
causing avalanches of debris into the crater. |