One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic tvb now,tvbnow,bttvb- e" d R* a: {
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are www2.tvboxnow.com5 p$ X$ k1 q8 |* z- p6 V
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.www2.tvboxnow.com. s" B n0 N% g% ^- R) u* q7 f) b A
Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
# ]3 m1 _" A% ?8 W/ 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。erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous tvb now,tvbnow,bttvb: B: y6 d4 l: W& Y ~: G
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. 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; v2 K( ^) t c
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.
7 m6 u: e8 t) ~9 X公仔箱論壇
/ A3 Y! I/ H& W- V9 D7 k
* m; ^. [ N5 ?+ G5 Nwww2.tvboxnow.comwww2.tvboxnow.com6 o! V( a" a& X- s# ?, f
Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above
! P# T. Z0 Q- }6 Z7 S( `www2.tvboxnow.comof Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewastvb now,tvbnow,bttvb+ Y# a: o% M0 ]. j# V5 c( L
taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash 公仔箱論壇% s g Y' n+ a+ }" n
plume reached as high as 50,000 feet.
9 O) R6 P! v5 Y2 M' i( 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。
" i( u4 v/ T6 Pwww2.tvboxnow.com / r$ |" E* X! U1 m6 n3 `( X ]
www2.tvboxnow.com( D3 F) }/ ]* l5 m. |
Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra 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 C3 p8 a" {8 a
satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
7 D4 e2 e, Z- w9 Y- q! W- GTVBNOW 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。years. The island’s jagged edges were created by massive avalanches.
0 G/ s' g' Q; u$ v! M; O公仔箱論壇tvb now,tvbnow,bttvb5 [9 d5 Z+ H" o. H- s/ V* B
Augustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring 公仔箱論壇. o' y# i* N4 v% r4 ]# T/ U5 e
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet 公仔箱論壇0 L0 U. l1 b7 h5 a
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
, [! ` G. x6 a' jthe continental crust, creating magma that drives the volcanic eruptionstvb now,tvbnow,bttvb! E: y% a8 `; j4 _! } ?4 j" |
! ]/ v! E. x+ v( c+ u/ ?/ D ) z$ k3 [; \2 a# r1 t
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 S( K. N5 t, {* ~1 p! r& j
Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
- [# O' ^0 t s9 \2 f6 b' V, 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.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 K, I( b- }& Z3 f! k- o) R
tvb now,tvbnow,bttvb" {0 o8 l; ]; j
The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising
, W9 D) K3 j6 i. r5 {7 P3 D. P8 z0 ?; y# K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 公仔箱論壇7 `6 O$ b. q6 M# k4 Y9 t
as a pyroclastic flow.0 H4 ]) p$ n1 }# D- v: H
4 K6 f% o% `6 V3 ~1 P* m5 qtvb now,tvbnow,bttvbThis photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up:
( m# |7 O2 L6 k( l3 U, W& qwww2.tvboxnow.comwww2.tvboxnow.com: N: p+ O1 W; J% c9 E1 d
* It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.+ x" M0 G) c, G. \" M
* A shockwave from the eruption could have blown a hole in the cloud deck.
+ s! B3 ]) q8 q6 J- W/ V( j * As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.% ?" x1 o$ L# \5 v# K4 }; ~2 ]
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 w' k, W+ g, s$ W2 o( J7 |
# m( U( d$ Y) y* }0 X! B& GTVBNOW 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。
/ s. j+ h5 h( V8 x6 ?Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
1 q) ?* K8 y' z' Q0 Q( vIt continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when公仔箱論壇* B7 i# d6 @/ y
the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.
/ e, h& w$ y4 G3 q* G. M+ W7 twww2.tvboxnow.com
' n6 b3 ?) F/ ]4 R4 s. ]' ?www2.tvboxnow.comRedoubt is a 10,200-foot tall stratovolcano 100 miles southwest of Anchorage in the Aleutian Range, west of the Cook Inlet.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- f4 V1 e5 t
9 i! F9 P& ?2 J- I$ U0 S
; C1 e- y+ y. A2 _' k& t: x& z, ~( S4 W5 _" b2 B" z" V# W
Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
. u7 r8 E2 p/ W- W9 g7 g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 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- H4 Y9 ^( @5 Y
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in tvb now,tvbnow,bttvb1 \9 Z! {9 h, u9 o
this picture are from forest fires ignited by lava.www2.tvboxnow.com' P2 D/ c0 d; Z S/ M+ R
q9 X+ O# G; [7 rEtna 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+ _& Q% X* ~: f
also be the oldest-known active volcano.
6 b" J! `8 `( Vtvb now,tvbnow,bttvb2 j8 @7 S! [5 ?. @# V( h# c# G
, v! W* O& A1 B! e公仔箱論壇
/ a p- q) O9 a公仔箱論壇A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high 1 A7 n0 V& Y% c7 R7 ]4 E
and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.公仔箱論壇7 B5 L" {* \; G5 p) m
8 J. I: k: q1 y n- [+ O1 @9 S2 f
 0 x5 X5 J+ k0 B" x9 D, s! z: }+ @
. z1 j! f0 [, b" Y- ] A8 k4 L( ?Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City.
5 q9 a) X0 m6 A2 W7 z" _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。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 tvb now,tvbnow,bttvb, z. N7 R3 `; u
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
) @: B: i3 t0 A1 b4 x1 lof frequent activity. The plume reached heights of around 30,000 feet.: L* C5 b) g3 A5 r. T& l( ~
tvb now,tvbnow,bttvb( Q; G, D0 q, I X( H& U7 s* {- @
: E. G2 E( r9 {1 u/ S+ c, 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。 N, t C! I! V: K
1 F( b) w" E8 ^, S. x: E6 X4 d' Gwww2.tvboxnow.com
) E) P' P# G' {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 eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the 公仔箱論壇8 r3 x+ x: ?3 V! B3 y0 W
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.' v4 h* b- \' ^# A9 g' _8 v. g) _' 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。% R( [4 X6 _5 g) {9 ?
Chaitén 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( a( F& ~5 x K3 v
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.
0 I N# P# U7 s& }8 l! Pwww2.tvboxnow.com
; Y( o, ^9 g# k& T, n" Y
6 B, B, T m6 {' b+ H8 Gwww2.tvboxnow.comwww2.tvboxnow.com* L2 M- ?- j3 @/ {& m1 `
This image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra
. g% K: _8 Z) d& j) A! Xwww2.tvboxnow.comis 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
% b) }* h, l$ f$ r4 I; d$ ^* c8 o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
+ q% F6 Q6 p% ?4 a9 P4 D: Ustationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
7 _' L# ~$ m& ytvb now,tvbnow,bttvb公仔箱論壇8 F2 n9 M2 d! {9 x
" o6 U8 j% j4 [0 l) }$ W# ]% p" cwww2.tvboxnow.com公仔箱論壇1 i4 C( D, F# k. W+ R) h
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. tvb now,tvbnow,bttvb- v/ F5 ^6 \5 V0 q& o$ U ~
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 公仔箱論壇* _* c! v5 [8 [0 U. @
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, - f! e/ F |% e+ ^8 b
causing avalanches of debris into the crater. |
發表於 2009-12-22 08:34 AM
| 
