One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic os.tvboxnow.com1 N9 Q% t4 ~& U9 }& H
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 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 b; N) \. L9 x7 B
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
0 K/ ?; k" X; b/ yos.tvboxnow.comSome volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens, tvb now,tvbnow,bttvb9 ]- [$ ]! L- v
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
# T: r; N8 y+ ^+ c0 f3 Zand explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. # i9 A, [4 D/ R% e
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 os.tvboxnow.com1 x; y2 Y& c* q% k" I* i6 @ d
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
4 H: r: M; Z3 G5 L/ g W8 {os.tvboxnow.comtaken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash 公仔箱論壇* W3 q; ~' d4 X* j
plume reached as high as 50,000 feet.# F9 ~/ j6 `$ C7 B" T D) C
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: s+ Z9 L. g" i0 o( K& xAugustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
1 q1 t- ~, _2 }4 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。satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000 公仔箱論壇+ [. A. a1 O! D# G2 W1 o" g
years. The island’s jagged edges were created by massive avalanches.
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; `$ s# y8 _9 N7 h" F7 V. W! v/ m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
l4 p+ L; r2 J/ R+ D. uof Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
6 h2 R8 g& D; n" p1 ztvb now,tvbnow,bttvbocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
2 k) [% i l. X8 I; ttvb now,tvbnow,bttvbthe continental crust, creating magma that drives the volcanic eruptions
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, P) G% @6 |; Z$ f/ @6 Q' |os.tvboxnow.com
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?7 X( Q) W2 Y; b. 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。Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
0 J, N) [! x" ] } C) \2 Q- 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。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 os.tvboxnow.com6 Z1 d$ L) j2 s0 e- k
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 # Q& e5 |; T; T5 w% u
as a pyroclastic flow.
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8 ~# t/ P9 }9 B+ a1 s# c/ oThis photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up:6 i! Z: Y y* J" [' n
: l2 T# m6 C8 r( a' {2 b- w. Gtvb now,tvbnow,bttvb * 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& i5 Y" S) |" p$ ?& k- ]
* A shockwave from the eruption could have blown a hole in the cloud deck.os.tvboxnow.com! a! u4 q3 |+ }1 l0 g# K" x+ V% E
* 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.
. i4 c. k6 l3 ?" _os.tvboxnow.comIt 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。9 k2 D) o3 r5 H" Q
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.
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6 g, l; J2 W4 P k) n( p: 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。
0 s7 \' y- D; \, GTVBNOW 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 inTVBNOW 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 W. }% f2 R' _4 y/ I7 Y
the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one
+ w7 _+ W& n8 u; a# l. ]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。captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
) e$ ~' |0 n& b9 Lthis picture are from forest fires ignited by lava.os.tvboxnow.com2 W v/ @- l& Q8 [! P3 A* I& x- B
! t: W& A; t/ S" z# ?6 k+ 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。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
$ A1 p0 g6 W: G& H$ Mos.tvboxnow.comalso be the oldest-known active volcano.tvb now,tvbnow,bttvb0 d7 O% t& N6 w; Q
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( k! i5 c" v( {/ z, rtvb 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 0 l& b& X2 M6 N6 _9 K
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+ q# j3 o9 s7 @% N9 p2 ^. q
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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
9 N/ s& \- s3 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。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
! k8 s0 R8 Z5 j/ s- s+ amultiple 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
0 G D0 Q5 U! y! E- ~os.tvboxnow.comof frequent activity. The plume reached heights of around 30,000 feet.tvb now,tvbnow,bttvb# B- B7 n! ~& _0 {' {5 U
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2 g9 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
& i5 A0 E, s5 U7 G! |4 hwest coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.7 A/ o+ F: y, n
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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
) z H8 m* g3 [( z1 M( Mtvb now,tvbnow,bttvbflows 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; r/ ?& |( X- r( @
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 5 L- p$ [2 F# Q3 F+ @; B& l
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
) T; B+ c7 t: j: m% yTVBNOW 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.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。+ C- r2 F) q# C( Q$ v' I
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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. 公仔箱論壇* j2 Q3 T9 z6 I) |# U S9 T1 _
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 # S& n6 i) W1 |0 S
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,
4 V& n1 K5 o) ]4 V8 I' ros.tvboxnow.comcausing avalanches of debris into the crater. |