One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic + o& E7 s! z9 r' Y6 w
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
^" K" C3 U" T" w$ x! f0 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。active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
2 x; }! c, }4 {0 n0 Ktvb now,tvbnow,bttvbSome volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
6 v( `& H; M- W& }! y/ e8 _# lerupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous tvb now,tvbnow,bttvb% g; e" p( \7 }+ M: X
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. 5 Q6 c% e. K5 s% @
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.
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7 n) F) Y# W/ h S$ p7 z+ uTVBNOW 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
7 l) ?" z% Y1 r% [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 Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
* s5 I) P8 H8 H! |- U4 |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。taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash tvb now,tvbnow,bttvb4 t# ^% R: N/ Z
plume reached as high as 50,000 feet.公仔箱論壇; a# u8 @- p k* G8 ~5 A3 E
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3 \* G! G8 { D0 M3 L8 ^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
2 ~0 n! V. w J9 ntvb now,tvbnow,bttvbsatellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
- W/ B8 d) \# y' X6 {& c2 ^os.tvboxnow.comyears. The island’s jagged edges were created by massive avalanches.公仔箱論壇2 Q8 |. H2 W; m, H9 r
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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 / ~, Z& _# Z4 R7 I: B B6 H# z
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
2 T4 d2 y" V. N7 |! Pos.tvboxnow.comocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
& @! o5 g. e. j$ d/ n) 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 continental crust, creating magma that drives the volcanic eruptionstvb now,tvbnow,bttvb% h% M: X4 K( S# x, ^3 O. |
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7 Q' b6 j$ i8 Y5 [# Q, F" Y: `- a0 A( p6 xAstronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
" O- ~, ~7 o# Y8 S, i0 f$ Y5 z" t- [in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.
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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
, h$ d0 s+ ~% Y' ]/ stvb now,tvbnow,bttvband 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 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。# w9 t6 R0 G+ K4 V) I8 b$ N
as a pyroclastic flow.
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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:os.tvboxnow.com+ c- D4 m+ \! H( H/ o* q0 p
) @" Z d% R, i$ J& l * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.公仔箱論壇9 |- s& F; B% S) a
* 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。% L/ I. V: w! @1 ]( B9 u( D
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.tvb now,tvbnow,bttvb# Y4 K! L7 l0 A8 W8 Q# O" x H
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Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
% {7 d3 J, G. E' s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
9 a& \4 D3 K2 p: E' n" ]7 J3 p 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。& {" X: w5 F2 M! b. C
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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.tvb now,tvbnow,bttvb+ A' ?5 Z* i B$ ~3 m
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; v% \ T g. K+ Y, h# Y1 w cMount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
( m4 }. R) J f6 e8 L9 Vos.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
( |1 K. ^5 G: o. k7 z' T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 tvb now,tvbnow,bttvb! m* s% f6 T4 r! d5 U+ E
this picture are from forest fires ignited by lava.+ L* j. U2 x7 T8 z: c$ i
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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 may公仔箱論壇' `, C6 } |# A1 p9 M; w' a% o% e
also be the oldest-known active volcano.
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A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high / b) Q, @* W7 l0 o% A, S$ J
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! s) j( f+ @) o
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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City. 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。& G# M, ]8 s* n8 ^
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 + n! t5 b* L! O9 I9 c+ {% i* [- f
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
5 O# A F' Y) M) B" }/ Y公仔箱論壇of frequent activity. The plume reached heights of around 30,000 feet.tvb now,tvbnow,bttvb. l3 J! T) q& E! E& ]8 h" i
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s& q8 b: [$ o: _2 ntvb now,tvbnow,bttvbThis eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the 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。$ g) h- q; ^0 b0 A, q
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.公仔箱論壇5 A0 z. ?' P7 i z i! C3 `% X
2 l3 c+ r0 W. X7 \Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic + f( j- ~, I) ]
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.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。) [" N2 e7 f6 o I
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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
5 q( G% \; F: w5 Mis 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
: K: }/ S4 a' g8 T! y P$ Z! M Z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 1 g: o: M$ ]% h) x( P7 M! R
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.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。 y* i5 k! R; l" ~' E; M
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( _+ L! d% o6 l. A- w( l0 ~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.
( F" \+ ]; q8 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。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
- t, C( f& J: q' g3 W0 ?6 fos.tvboxnow.comthat 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,
! w9 L0 W8 R; N1 X" Acausing avalanches of debris into the crater. |