One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic ( z& a o& f: K1 i% ?
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
% j4 Q) ~2 p; N9 ^& W3 ?! p7 yactive each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
' e4 y# {6 `2 t# HSome volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens, 公仔箱論壇* v" H& y* g% z
erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous tvb now,tvbnow,bttvb' ]9 b5 s, q$ L% T; e2 H2 {
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
4 n l8 @' b+ S: K6 V2 z$ k' U+ kThey tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape. a' h. x/ C4 `4 X" ^. g( @2 e
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。- p. j7 E: s: e( y# e
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。 m( @" N+ c7 e- ]( y" S0 h
$ Y6 t$ z& J* d$ k5 L
Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above
* P9 ^" K* N9 s: p& i1 |" b5.39.217.77of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas. l0 m! f- _4 z: |+ j% t: T" U
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash 5.39.217.77: `& [6 A- X. v1 [8 h
plume reached as high as 50,000 feet.5.39.217.775 b, n0 r" v$ G% V5 t f% w! W
1 B5 E4 n4 H7 C: c) X# }5.39.217.77 公仔箱論壇9 y7 F: b$ J% O
5.39.217.779 H3 t8 h" \4 P) S; q6 r
Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
1 Y8 N7 Y" |7 u7 D9 _. v: T z# gtvb now,tvbnow,bttvbsatellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000 5.39.217.77: i. Y4 C _' A, _, R( h
years. The island’s jagged edges were created by massive avalanches.
& C+ T+ y& B$ J" f3 Z L公仔箱論壇
8 E1 \% J. _" J3 \7 g8 mAugustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring
8 ~0 `/ I0 ~# B2 h5 R8 D# K4 Y( G+ h5.39.217.77of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
& L( {3 `& M- n: L. @ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of 8 G4 I b7 N) T( `1 F
the continental crust, creating magma that drives the volcanic eruptions
" n- Y a% o) D公仔箱論壇
3 I0 H3 i2 K/ U) ^ f" ]公仔箱論壇 5.39.217.77: f# g; `; H, N$ @& h, X+ K
% s" G' ]; l( m/ f r& r公仔箱論壇Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
& ^2 u" [$ h# p) V+ 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。in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.* H9 l0 X8 \5 u8 r8 a
+ d0 L2 K# H0 {2 C/ }, f& u8 W( W5.39.217.77The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising 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。4 P2 F9 A0 r, A( S5 O( X
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
- C. V m# T+ _' Z- d: T8 t5.39.217.77as a pyroclastic flow.tvb now,tvbnow,bttvb; ?* K# ~7 q5 @: m& u: A
公仔箱論壇; `% a( [- ~* T+ X; E2 w
This photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up:
: I( K4 H- v" }; ]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。. _9 h/ I2 P) a) F( M# L
* It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.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。! L6 K) m3 }( C. ~0 I3 g
* A shockwave from the eruption could have blown a hole in the cloud deck.
0 e- j: g- z! R公仔箱論壇 * As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.5.39.217.77! O/ P0 P: T9 @
5.39.217.77. n+ e$ H) \4 _3 ~
tvb now,tvbnow,bttvb% `( U7 _9 @1 p( j- T% \ Z
公仔箱論壇* [2 Z. o! _5 x! R' i$ Y
Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet. 公仔箱論壇. X" I1 a: l) {
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
# _6 O: a$ `0 H* v5 g5 J the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.
& V" _' l+ B0 QTVBNOW 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* _! n3 D* s$ I! @0 U: _
Redoubt is a 10,200-foot tall stratovolcano 100 miles southwest of Anchorage in the Aleutian Range, west of the Cook Inlet.- j% `' q( e" n0 K" E) H) Y
& A) W" n. l- W" O$ D' h9 ^; s5.39.217.77
5 b3 U0 g3 }3 d# [; i0 B5 t! s公仔箱論壇5.39.217.779 _; N& w9 Z; @
Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
) W9 C# e- m" P" E- f4 H' O! F( y; a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
1 A; `* E! F! R8 z5 jcaptured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
( X/ [& N, F3 F) q0 v# X$ ?公仔箱論壇this picture are from forest fires ignited by lava.公仔箱論壇 w9 z! m' o) D4 Q
公仔箱論壇+ R2 N+ X, G) G; l7 s
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 r5 }! |8 G4 {( P: _) zalso be the oldest-known active volcano.
( _( @9 Z1 v8 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。tvb now,tvbnow,bttvb; E; \5 {9 v# u g/ Q5 ]+ g2 @
公仔箱論壇: P; @1 j2 b- d5 I# V+ `
9 S# g: o! U8 P% n
A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high 公仔箱論壇6 t$ c* ?1 a5 U
and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.
( F# r2 P0 Q4 u6 J$ E/ O. K公仔箱論壇
2 _/ L. n9 G. f4 m. ?$ X3 v tvb now,tvbnow,bttvb+ r2 W0 T7 J! X. w6 Q# ?, B4 j) y
$ C" \' A S; W( [2 i9 W9 ~6 K: ytvb now,tvbnow,bttvbPopoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
1 _8 m, x+ j' s, c. b1 }5.39.217.77The 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 5.39.217.77- a! k2 {' S( K
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
" E7 k- H$ K: p( Y( V1 c# rof frequent activity. The plume reached heights of around 30,000 feet.
& V, J2 }, ?9 _8 I' P4 ]6 A: `公仔箱論壇" M" {! c3 M; c" Q' P' m9 X4 d4 i
5.39.217.775 r- X3 D) v! [
1 Y+ t6 _8 z8 q0 r7 p$ N
5.39.217.77' E) z" i' q% p4 q: c
% D9 H; {! \" ?6 h+ `7 k: f4 D- V% L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 tvb now,tvbnow,bttvb& r ~$ [$ ?, D$ a: ]
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.
5 E3 t5 G# T- G- W
7 ?: k/ b% m- i B# |9 Z5.39.217.77Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic
' g# }) P0 j7 o+ E7 Z3 {5 S9 z3 g! mflows 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.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。1 a! v5 i& d% h0 a3 s
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。5 f1 e1 v' O+ Z6 U- F& p& E
5.39.217.77# f; ^+ q5 l) Q0 j7 y2 H6 Q( \
; X" e/ o" l% q/ z3 V1 U
This image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra 5.39.217.778 ?, N) j/ l" r) g
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 公仔箱論壇8 {/ C$ O. `2 _" w
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
: ?4 a/ l3 D- b4 K; z) L; ]6 Ustationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
6 w2 g4 n+ r$ {0 v, ?, K, s4 Vtvb now,tvbnow,bttvb公仔箱論壇9 S5 U2 G; z; @4 d" [

. P3 x% w2 L1 R; I" ]
7 i* [1 d7 _6 }+ ^' x( r: i* ?$ qNASA’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. : x3 s; }) I, A, ]
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 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 m' z! c% \. `+ D3 {
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,
1 R+ ?, t4 G3 ]1 }2 xtvb now,tvbnow,bttvbcausing avalanches of debris into the crater. |