One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
' j: t- R/ ~+ \$ j. P) i5.39.217.77eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 5.39.217.77! q! U% K; G8 }+ @
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
7 @4 O- ]% H3 I& D$ X6 l公仔箱論壇Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
5 S$ b b9 B, V公仔箱論壇erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
/ I' f! c6 M' i1 @3 _3 T9 a5 @and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. tvb now,tvbnow,bttvb2 Q' K2 @ b( M D
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.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。3 _9 O+ v( R* Q8 }& \1 t
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0 B; I& L0 D. x+ ?Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above 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。6 O! Q/ s9 h8 I& ?0 E, v
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
% F( b( J0 o1 U7 Q! o2 p6 JTVBNOW 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 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 Q( }* L) I+ ?4 l! s
plume 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 tvb now,tvbnow,bttvb8 _2 U1 Z$ B, j b- W5 o1 H" l
satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
4 a" P @% y" Y3 ?% p" l' Lyears. The island’s jagged edges were created by massive avalanches.tvb now,tvbnow,bttvb& |+ |- g' i8 @* k% K' O
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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
4 q" y/ \* O y3 X A5.39.217.77of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet ) Y: u; Q6 H, i! Y: u7 K/ `9 ~
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
0 Y }3 L0 @8 B0 s; Zthe continental crust, creating magma that drives the volcanic eruptionsTVBNOW 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 w2 }# x X9 ?. q
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Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
3 C9 w) x9 g/ d* }& p5.39.217.77in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.
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4 s7 n# ?9 u) s3 a: A- Y5.39.217.77The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising 公仔箱論壇( X8 _. L) H- G- @
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
$ X: E0 U9 }- Y R* p) c: 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。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:公仔箱論壇/ \9 ^: I9 V* x
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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.
- b7 o% n5 J7 K7 I4 |: w) c9 A公仔箱論壇 * A shockwave from the eruption could have blown a hole in the cloud deck.
7 t4 V t; K3 k1 J- F' F |公仔箱論壇 * As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.# o2 z; [) l# ]" b. Y- J
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4 @- ^+ s6 r3 ~7 e5 ?& IAlaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet. 5.39.217.77& o$ l( F0 }& v3 t! w" r
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
/ ^; v" [9 }4 K9 s5 z# ] the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow." b$ {" G) y0 ~' x9 g8 \
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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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# [9 ^* g6 B; f, z0 [Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
' _1 K: [" e$ {+ O) l公仔箱論壇 the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one
% `* |# \! |% O8 J( V% ncaptured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in 1 A9 V( x/ ^ c) e
this picture are from forest fires ignited by lava.
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5 j! h8 c* p3 R% l8 Xtvb 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
# Y* Z" g! C9 `, y Qalso be the oldest-known active volcano.公仔箱論壇8 K' u( i/ u: u5 X$ Q9 k# f
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3 p7 N- X, V9 A# V- B/ Q J& y% Y/ @A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high
. S* ~, s" [3 j: F* htvb now,tvbnow,bttvband 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. ; ]1 }, I+ Y8 S9 p7 w! E4 r& X 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
3 h2 }4 e6 [. g2 k. H! y8 z+ tmultiple 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 5.39.217.776 v9 D6 N( C. S! R2 j* N7 O7 D3 O7 Q
of frequent activity. The plume reached heights of around 30,000 feet.
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/ Q" j1 z6 z; _# r' T3 Y1 Z) D' EThis eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the : \! P. j% h5 E% _8 Q4 E( S
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.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。/ D6 Q* i8 N% P
6 j2 }5 |+ a& 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。Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic
7 x% B8 n; A& L! N" R nflows 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.5.39.217.773 h& O4 K$ y1 R! W/ P2 b: K8 j
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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1 f8 W, \$ X' @% s, G% w& f# B/ Z+ V
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 9 h X) A+ b1 f3 ^
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6 O) x" {! Y" [; X1 ~
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.' |! K/ P! }/ A# N. v6 F5 Y
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" ? V3 \: S- h# o5 k' I+ p* t公仔箱論壇
4 m5 z. W$ U& |: DTVBNOW 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。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.
~ I( ]5 H) Q% ?7 C; YA 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 % M" n. Z: V. G( ]
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,
' v! `8 ^4 f) q8 G- @$ h2 Ytvb now,tvbnow,bttvbcausing avalanches of debris into the crater. |