One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
" [- y. W: O9 _' @1 o, reruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 公仔箱論壇3 f0 s1 t! @5 I, [% B- D1 l, z' @
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.tvb now,tvbnow,bttvb: Z! B# ~) @" F
Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
0 q" M4 X+ |7 J0 Q公仔箱論壇erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
" A/ U* A+ J, }9 oand explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. 公仔箱論壇! x2 ~) |" Y& u2 \ h# Q2 j* Q
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 tvb now,tvbnow,bttvb& J) e% F$ D, ^' `
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas# q$ G; X6 a# p
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
3 r+ S& T/ ]9 g/ B9 F/ @& K S5.39.217.77plume reached as high as 50,000 feet.: T# g, P% q# d$ Z' D
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" g" t1 A7 G3 }6 j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。" `0 l" F( C! R; B. p8 N4 X
Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
/ a' f W8 j# E `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。satellite 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& L* O: r$ o2 t$ J
years. The island’s jagged edges were created by massive avalanches.
4 x6 Z, K, t0 I. D; _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 D3 C4 O+ m/ S' G& a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
5 D+ i8 S9 U0 r* j5.39.217.77of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
+ m# j$ y2 G+ ]2 h7 S" focean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of ; e0 I& O( r1 ?3 n& V+ z1 C
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 公仔箱論壇( a$ W7 k4 c* e( b0 f- S5 ~- C
in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.; ?( G' R h/ h) W8 U S
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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 3 o' F" c# M: d ]0 A
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
( [% p9 C! v4 I) etvb now,tvbnow,bttvbas a pyroclastic flow.公仔箱論壇2 e1 N% M9 g0 `
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This 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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+ n" j0 W! U/ V) m: e * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.5.39.217.77) f6 U7 {, o% R* R
* A shockwave from the eruption could have blown a hole in the cloud deck.
O' P2 q# d: O8 i * As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.
$ |) V! n: o- s, @! V2 FTVBNOW 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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- n3 p2 G; N& [& HTVBNOW 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。Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet. tvb now,tvbnow,bttvb% h+ u# L, K% b" o
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。8 G9 v3 ] C9 K5 H
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.
9 v( _- I5 V6 K% `3 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。
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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 d* @: r' l: `
the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one tvb now,tvbnow,bttvb; f6 u% t) u x6 h8 t6 |
captured 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3 Q1 h" S: X0 s; g
this picture are from forest fires ignited by lava.
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# e8 Q) z- N4 ?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
$ a4 o# f# P+ Walso be the oldest-known active volcano.) x( E6 `* [( V
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2 [ s7 I& S4 K* n% C- B7 U. G0 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 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/ c" S# z% w
and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.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。0 j- N* }7 g: i5 h
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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City. ( c/ `0 ]% A- o6 h" @
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 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 F( a# z n$ r) 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 1 k3 P0 c4 \7 z$ J# p# f
of frequent activity. The plume reached heights of around 30,000 feet.tvb now,tvbnow,bttvb+ {8 k' Q% J3 M' n
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This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the 1 z% X; R3 v& }3 q6 A! k
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.
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. f c; w+ d g: I8 ^) b3 Ptvb now,tvbnow,bttvbChaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic
" U) ?8 T" L2 X8 kflows 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.tvb now,tvbnow,bttvb9 U; E/ z; l! ~2 P" X' E4 l. W
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$ `" _! S; Q0 l5.39.217.77TVBNOW 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 Z2 |6 h: E- y6 F9 O1 K; z3 R
This image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra
% R2 }7 {/ \* N' \, ^, Q v3 \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。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 2 I# q( ^+ p2 H2 z, X( M
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 公仔箱論壇. v. s+ W; G G# [8 c0 U
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.% v! S; J, G. ?+ I, {/ ?' d
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1 B6 `0 B% t. N ~9 t7 X! G$ wtvb now,tvbnow,bttvbNASA’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.
& M9 R9 v8 `7 Z5 h9 btvb now,tvbnow,bttvbA 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 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 i: _8 E. Y+ i. ^$ o
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$ L4 Q9 D, r! |# d" ^公仔箱論壇causing avalanches of debris into the crater. |