One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic 5.39.217.77:8898& A7 d' Z! Y# Q4 w. C
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 5.39.217.77:8898# q2 g+ Q3 c7 V* Z8 g/ H( [3 ?
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth., h0 q2 H3 D, w; w* ?
Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
; \! ]2 r; O2 @ }, kerupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
6 M/ X8 S2 P1 `# v% D3 A- Uand explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. 7 f- `8 L5 G4 i& M2 ^
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.5.39.217.77:88989 P& w% ?. e3 J
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% S4 ?0 d' ]. ?! D7 c* \Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above 2 \5 q3 K3 z+ L) P x; H0 [0 {- Z
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
( S9 s! v, j5 \" vtvb now,tvbnow,bttvbtaken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
3 s+ U$ {; C( T. s" {3 gplume reached as high as 50,000 feet.# P. F$ A Y; |
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) w4 x( w/ Z; X gtvb now,tvbnow,bttvbAugustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra . l+ J$ l7 F0 G, o
satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
. g+ a- E3 A( @' c9 qyears. 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。: A9 {8 s/ p5 S8 H. u4 Z
) i2 m$ w* [/ S- O, r4 _8 FAugustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring
+ I- [ |' o. o& A, b; 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。of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
* j( G6 u( Q, ^1 c2 B% ]7 o5.39.217.77:8898ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of $ p$ w8 s1 j/ D6 Q$ a
the 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。 G8 k# _, J* }' `$ j& h
0 @8 y2 N- ^# w" Y3 Z" _5.39.217.77:8898tvb now,tvbnow,bttvb; K- k+ E% P& A; ?4 r. n
5 ]. N$ H9 c0 z8 f' @" Z3 Z4 dtvb now,tvbnow,bttvbAstronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
2 Y3 _6 O& z. X2 K- j. Ain 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 ; K+ O& j" R; M2 v& l& ]' z
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 公仔箱論壇' { C2 L+ j6 [# s/ i& w
as a pyroclastic flow.; o: u1 I8 P6 {- L7 Z
3 T" D7 Z5 H# A- v9 | }! dThis photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up: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$ I4 b0 C7 |, S7 @
. K1 `9 b. G$ O, p! A+ O {2 B' y! Z * 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( u8 u! Z$ D" r! P
* 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。& x/ L; j" \# t5 H0 {) U
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.tvb now,tvbnow,bttvb) X- {9 z. h& X8 N
$ f1 o& |' F2 u$ Q* a) n' a" L6 Ztvb now,tvbnow,bttvbTVBNOW 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。- ~5 e6 u1 @7 O* T. a
4 |2 L) X. L: w5 p( ^8 I8 s( T5.39.217.77:8898Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
: D; L; W# l8 p( wtvb now,tvbnow,bttvbIt continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
* X2 \. @1 A9 w7 A; S3 u3 ?tvb now,tvbnow,bttvb the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.tvb now,tvbnow,bttvb% S5 Z! }& O* ~! T8 x# a4 F- k
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- z) {% j$ g C
Redoubt is a 10,200-foot tall stratovolcano 100 miles southwest of Anchorage in the Aleutian Range, west of the Cook Inlet.公仔箱論壇9 E0 d' t s0 p' b1 o* O8 _ M5 C
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9 v& q/ ?; G+ z! A, r6 A5 p7 r3 I% vMount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
7 n9 X3 m5 I% X, [5 F5.39.217.77:8898 the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one 5.39.217.77:8898% q( c4 ?4 o8 F1 t! M
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。 J$ y% Z2 B2 y3 O
this picture are from forest fires ignited by lava.( x+ X: q0 }1 c! S
/ F M! y% q* L" W 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。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
' H; ^- e( ]( u2 t! _5.39.217.77:8898also be the oldest-known active volcano.公仔箱論壇9 j) a/ }, B7 b; c/ u$ D0 W8 T
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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
/ i$ l. T! ]3 J# a ~7 z# {- 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。and 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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/ K. b# `, _! P* l3 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。: r4 A' R& r' g4 [
Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
' u5 n/ R: C1 | G9 w6 s& a- iThe 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 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# ]4 N' P' q
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 5.39.217.77:88982 @" Y, f9 f* {" ~8 r+ C
of frequent activity. The plume reached heights of around 30,000 feet.
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This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the 5.39.217.77:88989 f) J0 C# l7 h
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.
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! m! ^- v, P6 ^4 k: lChaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic : f) H1 s, ^0 V. j
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.5.39.217.77:88986 _/ [: S* r7 P- |# V# p; n+ I0 z
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0 Q8 Z; r9 A8 l0 h# ^ k5.39.217.77:8898This 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- H6 x+ k/ t0 B& }. e$ b, \; A
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
2 @" b, N) D+ ]( M' s% z! a3 M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 ) Y" z6 n% g; W! T' v" e
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
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& \0 b& z2 F8 }+ Q3 W+ }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。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。: p0 |% ~# a" [% c' P) b6 F
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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。 L M0 Q M9 q! x, `6 W0 |+ f
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
7 p. v* A# a6 H; b. b3 a. T+ A7 KTVBNOW 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。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, 公仔箱論壇) O; {* b% S9 J4 M9 [4 U' E# Z: E
causing avalanches of debris into the crater. |