One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic ?2 d) b7 ?+ L: p7 Q
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
K7 O% f1 x/ E5.39.217.76active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
. w; I; ~' o7 n* B% J! P Utvb now,tvbnow,bttvbSome volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
- v3 G/ f1 o7 v4 c7 ?, o" v" |, z( Berupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
[, J0 s' A8 q6 a( {' 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。and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. tvb now,tvbnow,bttvb- F* l) ]# L9 j/ d/ p" r2 O
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.5.39.217.763 I* \7 x0 h& m8 A$ ^9 m
3 Q9 n/ ]+ m, u
公仔箱論壇9 a+ @2 |6 Q" N, Z
% q& w% {0 c6 W4 b4 D) f1 b: ^5.39.217.76Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above
3 F% V! [: _( I公仔箱論壇of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
, C% ~! N: h' wTVBNOW 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
% A3 l" Q: B2 \6 `3 Fplume reached as high as 50,000 feet.
- _, O9 }& k, N# {, r公仔箱論壇tvb now,tvbnow,bttvb- n3 t1 Z/ M2 E% x, ?# G
5.39.217.76 ^+ N1 r, {0 ]
公仔箱論壇# A0 R% z6 h; g* r1 _ s6 O+ h! H$ D4 p
Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
8 ?/ K+ l5 e; ]* X0 u( Lsatellite 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) X1 U2 {5 O6 X) v" T
years. The island’s jagged edges were created by massive avalanches.tvb now,tvbnow,bttvb A8 g/ }0 f7 X: {
5.39.217.76" ?4 O. a f$ v9 e! Z& j- }
Augustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring tvb now,tvbnow,bttvb Y c3 O0 w* }5 q1 y
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet 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。: I# Z6 `- D3 _- N8 r
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of ; L$ x3 o3 I6 ~6 \
the continental crust, creating magma that drives the volcanic eruptions5.39.217.76- @: k0 n6 U0 d) o5 t) |5 v
公仔箱論壇; o: T5 {2 s8 I4 @% G
公仔箱論壇0 \( {9 l" |& N5 w6 v2 x% a; f5 F7 d
5.39.217.765 }3 Y3 S; a: j3 S6 g
Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
& h7 T6 G9 N4 n: t. f& U' Vtvb now,tvbnow,bttvbin the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.tvb now,tvbnow,bttvb4 Y9 L6 K! c% |% [6 e
. ]% Q; [9 a/ M7 }) ^; R R `
The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising
3 d+ x! l, }3 E6 G8 A1 p# u" A公仔箱論壇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
3 k. s D9 U9 D. x4 Has a pyroclastic flow." X% P; r4 b0 t/ |- G
0 x* ]- r1 S# ^3 h
This photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up:9 o7 ^6 P$ t$ A d- w% K# D
' O( x; T+ z$ Q& p. f* n/ W' M5.39.217.76 * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.公仔箱論壇5 ]! T$ T, q) r" Z. ]4 J
* A shockwave from the eruption could have blown a hole in the cloud deck.. d5 \1 S( ]( w
* As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.公仔箱論壇; m, ^$ p4 v& I, p( k: w, J/ \& V: F
tvb now,tvbnow,bttvb" a6 }; m8 _* g! L( L0 ?

! ~+ s4 D3 U7 B/ F
8 w8 N4 D* T# l7 I5.39.217.76Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
$ K# z: B0 _; l/ B& q- c' Y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
6 V5 r' `- T9 P" O4 \' U8 _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.公仔箱論壇1 j- U% s; @/ \+ k: O; R
+ a5 c/ @2 O$ q, y& ^1 \1 i
Redoubt is a 10,200-foot tall stratovolcano 100 miles southwest of Anchorage in the Aleutian Range, west of the Cook Inlet.5.39.217.76& |; [2 ?1 ^3 I4 W9 o8 m* W+ ]+ a
tvb now,tvbnow,bttvb6 P! a- o( K5 ? h7 b

5 c6 @* q/ j0 M+ U8 W2 Z
3 t: k! |1 f# b, S" D1 @公仔箱論壇Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in+ B4 |( x1 w& p4 Z
the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one 5.39.217.76/ I9 M4 `- a7 A1 x% g
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
( `! {% Q2 ?& E G# N: [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。this picture are from forest fires ignited by lava.
$ a4 t. f& X: B1 ^$ 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。3 l6 }# j% P$ w# U' O
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
6 r) @# H3 q+ Qalso be the oldest-known active volcano.tvb now,tvbnow,bttvb o) _1 f2 Q& 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。" {. Z% ]& M; _/ l2 ~
tvb now,tvbnow,bttvb7 f8 E* Y& {+ o. v5 d8 T" R
tvb now,tvbnow,bttvb7 Y& e/ N/ z; V1 _# R* w6 B& I
A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high
6 i( J4 c+ f$ j# }3 C* C) ]5.39.217.76and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.5.39.217.769 F9 \' v1 j7 O- f" Y% k/ ^% D
" \# e9 Z8 n% o7 E% W( _公仔箱論壇
! {- C5 `) i6 K/ @, T: w i
- _& Z+ C+ L; A" U- |- ?5.39.217.76Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City. 公仔箱論壇% T. @$ U; @6 S7 t; Y2 \
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
) M; `0 d$ t8 nTVBNOW 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。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 # u# `* o3 }: \0 i# `
of frequent activity. The plume reached heights of around 30,000 feet.
0 z6 C! ~$ c6 wTVBNOW 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 k3 N# Y, V8 [& E. V# y- h# {& stvb now,tvbnow,bttvb
$ p% K, k* G! \: y, a公仔箱論壇
+ G5 b/ s3 U/ t# ^2 S% _9 F5.39.217.76
) b$ l# t/ D, k5 XTVBNOW 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。5.39.217.76+ {# D; m2 t) N
This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the " B& z: ~" N; t
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.
# A" ^" Y% g! O- f1 d. B% 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。公仔箱論壇4 ]0 [( l7 l; [
Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic
5 Y: @ d6 F0 ~- I+ d- O Dflows 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.
! N4 r9 t6 W0 s, n% h- Otvb now,tvbnow,bttvb5.39.217.76/ I. k/ W8 ?4 n+ f% Y+ _1 y

1 a" \; F0 ?/ F# S; R) R( _2 x5.39.217.76
( ?3 h( }& Z% U" \& P$ w. U5 D5.39.217.76This image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra 0 R1 s T3 H# w: T
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
3 ^3 c& ]* a# a- s8 q0 Mformed 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
! b `& E# r& x t% x公仔箱論壇stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
y7 y ~. S/ l1 Y3 utvb now,tvbnow,bttvb, N& ~& c3 r4 s/ m
0 y3 _1 r) }7 @/ t
tvb now,tvbnow,bttvb/ m; ^) ]$ c7 v) F$ Y3 [. ?6 `% k
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.
2 T+ } q! L; V- T6 U+ o" Y5.39.217.76A 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 9 |) d) V0 _% {
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, a$ \0 x& ]) M
causing avalanches of debris into the crater. |