One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
! l/ Z* X7 J4 g- h# ^$ 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。eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
0 ~* I" B& k) o W' k# A, D n K公仔箱論壇active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
) E4 k9 l# G' }7 x! {5.39.217.76Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens, 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。, M8 u4 y6 y1 ?$ P
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous 2 v% Z: i1 s) W6 [
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. 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。" ^7 Z0 X3 G: S$ P& l4 S
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.公仔箱論壇8 t- q2 {7 j0 F
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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+ n, h* j0 p4 }
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。4 y/ m6 W X: v5 X& s
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
# ?: y/ j I+ K8 C1 e! T公仔箱論壇plume reached as high as 50,000 feet.
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$ q$ v1 I4 m1 i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
4 ^ L4 l: S# \9 J$ P5.39.217.76satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
6 h6 K' ^# O$ b$ O. V0 c5.39.217.76years. The island’s jagged edges were created by massive avalanches.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。! J; {, V$ F) s: z- u/ V
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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
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ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
( T3 M, Z9 h( Rthe continental crust, creating magma that drives the volcanic eruptions
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; a! Y- O) C2 r, g$ _* AAstronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
+ z) P1 o9 ]- M4 r# T* @5.39.217.76in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.
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+ p# Q( o1 X- |- u5 u0 f# ]The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising : h5 S! g" b1 M
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,bttvb4 e/ p$ J; F! M) J/ d
as a pyroclastic flow.) o+ l4 L+ q3 z* V
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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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* It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.
4 b1 y# w$ Q& r公仔箱論壇 * A shockwave from the eruption could have blown a hole in the cloud deck.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。4 h$ I* ]- `/ B% p& s. M
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.
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Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
, h: Z2 U- D( f! E* L5 SIt 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。# Q/ @+ i/ @/ d1 a+ F( x$ {) b
the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.公仔箱論壇% }& n$ b) G( d5 x5 U
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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.
6 c/ Z+ V0 \* e; `' n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。 J" C0 Y V& k7 \% q
5 E, l6 z9 F! O0 f! d6 r; 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。
1 \. [) S% b1 N* n1 ?- bTVBNOW 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
# R& B9 y; J# ]- ]) K( ]) NTVBNOW 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 world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one
+ E( L+ x; S4 s7 d$ Y- [公仔箱論壇captured 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。0 i8 I x6 I) E6 s2 Y, Q
this picture are from forest fires ignited by lava.5.39.217.76% N. I2 y! |1 ?# 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。* U: q [( K7 `7 M' T# f
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& _+ ?6 s1 Q6 i3 L9 T' b. e
also be the oldest-known active volcano.# Z5 |* O: J/ ]2 P6 c
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w: c! Z) \+ H- l5.39.217.76A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high
8 h: ]& q G) n/ Y% N- y4 U公仔箱論壇and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.% r: F" Q9 p8 R" Z/ Y; X5 [, U
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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
$ S4 [0 r( n5 }' [5.39.217.76The 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 6 K) c/ ^ e: S/ ?. u% D
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
P. U) I7 t" }/ Y; Y6 |: ?# H$ e/ ]公仔箱論壇of frequent activity. The plume reached heights of around 30,000 feet.tvb now,tvbnow,bttvb9 \; D3 G5 X& K& H
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* @6 u* O4 j- S% e6 \7 O4 o0 o5 PThis eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the
) F \ @' @' C2 Pwest 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 5.39.217.760 c/ G' T( A0 ~
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 公仔箱論壇; h" w4 a, L. m
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
8 X8 b3 D/ ]- a* t% P- {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
* E8 Y) M2 f" C6 o9 t1 Y* dtvb now,tvbnow,bttvbstationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
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! C, P6 ?0 c2 ~; ~6 R/ S! S5 [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.
# d i5 ?' D5 l- d8 \) x+ 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 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
2 S# O5 _1 Y% d! U6 c; lthat 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: k# {$ P& \/ \# L6 @: x7 L% x
causing avalanches of debris into the crater. |