One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
1 }) H: h1 M& ?2 G6 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。eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
( @8 J: ]- G/ V& S! Y# O8 M0 zactive each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
' Q: T* L' f3 J1 E, o' P6 }& tSome volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens, ) h$ {( V7 U- q* e, a
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous 公仔箱論壇: ^& ?& N a( \1 [8 t
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
) [1 `: `" R6 J2 w) R# b+ l, H公仔箱論壇They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.公仔箱論壇 J E" @ m" _
9 ^: n6 K/ T" S9 q3 m1 x+ i5 y 公仔箱論壇! r" _+ u2 R+ U' q9 ]5 p3 @
% |. L2 A Z( H) E& C( E' 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。Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above 7 T9 |; V5 k- Y' B- o0 a
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
% l, ?/ d7 Q' \$ |taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash . T$ J! R4 E* d; `7 z
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
% h, {8 j6 Q3 l! v2 |9 Lsatellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000 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。( Z$ Y8 U6 A; U6 v6 O2 X+ N
years. The island’s jagged edges were created by massive avalanches.3 R- H6 D: E% p, v X5 E
9 \- J' a6 @6 Gtvb now,tvbnow,bttvbAugustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring 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。) n" x- x# y6 d/ {' L9 P
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet " k; C l. s( ~; ?( H
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of G$ }$ n# @8 ]0 @( V
the continental crust, creating magma that drives the volcanic eruptions
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4 {. q8 ]% N7 R1 c$ y2 x公仔箱論壇Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
+ Q, u5 h4 t8 ]5 K0 i公仔箱論壇in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.tvb now,tvbnow,bttvb7 ~" ~/ y l% p( e& n U+ T! b
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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
7 N: R2 ~7 a$ Z; P3 Z5.39.217.76and 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 公仔箱論壇: K0 n' @/ s" Y6 U# v7 Z
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:
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5 L }! i1 u# f) L: X9 @5.39.217.76 * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.5.39.217.767 p" }, t3 K* r: d1 _
* A shockwave from the eruption could have blown a hole in the cloud deck.5.39.217.763 }# X! E9 |# J* h' J
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.
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8 p4 L& x$ b$ q0 k% T+ 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。
$ ~$ {( C' T- }+ ]: @( h ~. |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。Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet. ) D3 o" F2 l1 I3 `) \
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when3 Y% U6 K1 W3 H9 c9 {5 g
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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* r2 O5 K* X1 ]Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in5.39.217.76% d- \! e/ c- x0 G' N' o2 m. n. B
the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one
2 r) r( i, f o& B- p# ATVBNOW 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
) f. l; M% a8 Q" K- `0 Kthis picture are from forest fires ignited by lava.
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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# w, x% q; B( e' ]0 ]" u8 a9 B. r9 b
also be the oldest-known active volcano.
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0 v9 L5 m" ^* K7 k0 h1 d, 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
. a) \: ]* Y, a' I: kand 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. o8 U% e# u- Q) ^( l b! f4 F: k+ H& k
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* a2 K, [, ]) `5 {8 itvb now,tvbnow,bttvbPopoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
- p! N) j [- [8 C- X- M+ sThe 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 + G, b) `/ ], ~
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 公仔箱論壇$ T) [, M; L% Y( }
of frequent activity. The plume reached heights of around 30,000 feet.公仔箱論壇/ d: y* g$ O: B* Z% r% s% F
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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。' d8 S' D. Q! G9 o1 G! I6 Q
- N- j/ l. T0 P2 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。This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the 6 Y: Y- L& }2 E' ^
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.5.39.217.767 h/ H3 t& x a0 {
: E G ?& J! V- e" _5.39.217.76Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic tvb now,tvbnow,bttvb f8 {- a* o0 }2 U; e
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
- t8 I a7 X( d! N( b7 }2 Xis 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
/ H, E( i3 V0 `: r# i9 P# K B2 d5.39.217.76formed 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
2 d7 f; _3 I$ M- y e9 lTVBNOW 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.tvb now,tvbnow,bttvb0 _+ @) z! b' k+ q
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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. 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。, F* J4 N! p; L) k0 i" k
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
8 U+ p! m4 ^* F! N! R/ ~* @* |. m! ~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, # o2 I; j/ S8 I8 k6 C. b& _
causing avalanches of debris into the crater. |