One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
! P4 G& K8 Z. F; z公仔箱論壇eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 5.39.217.76, b0 U; l0 V4 ]9 Y6 k, A
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.公仔箱論壇# }/ G7 L9 f' l# j: Y
Some volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
0 d$ _; b$ c) i0 b$ I, n9 perupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous 5.39.217.766 q Q' w5 @1 G$ ?9 ~5 u: W
and explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
2 H- ~2 k2 Z0 B: d; [9 W* p公仔箱論壇They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.
4 F. O) q$ K! Z; B公仔箱論壇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。; q, F# H$ N" c+ X7 S) X
公仔箱論壇# H3 n$ \& g/ ^" ~: V* w8 }' a
% u& P7 U4 p5 _ D' J' J% d! X9 c
Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above 5.39.217.76* k& F/ b: @( X- p) M
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
, {/ L) R6 ^4 \7 X5.39.217.76taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash 公仔箱論壇4 H% m% u9 L' p7 E+ e9 J
plume reached as high as 50,000 feet.5.39.217.768 e" q. [2 `$ D
tvb now,tvbnow,bttvb+ r4 Y, U6 T( C
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。( w2 R- j+ Q, t" i& }" |
tvb now,tvbnow,bttvb7 i- P! T2 k, Q# l5 ?' w1 m2 l
Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
" M$ `7 w5 C& Z' N: A$ V7 R, x公仔箱論壇satellite in 2006. Augustine’s dome collapsed in 1883, during its largest historical eruption. It has been erupting for at least 40,000
' w: y0 |2 C" n, g3 C5.39.217.76years. The island’s jagged edges were created by massive avalanches.
# R' k( o2 K$ n. u. q @9 ?公仔箱論壇
5 [0 o- H: `* c( b1 L$ 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。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,bttvb3 K0 g! ]7 W/ q2 T6 W/ w: i
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+ Q6 Y8 r) C- u9 ]' b
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
( }$ \% M% T7 J5 N$ y$ Q5.39.217.76the continental crust, creating magma that drives the volcanic eruptions公仔箱論壇6 b! G6 @/ q9 v" O( M7 K, r
* g( @6 c/ F% R3 L1 Jtvb now,tvbnow,bttvb
' H. c' ~8 Z; V" E
1 r2 W( [) T) m; J) ]Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano 公仔箱論壇" W& c# V# o5 f
in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.
& C5 H) F% \3 s B2 m C, ?8 G/ s$ A5.39.217.765.39.217.764 Z! I* @" S8 T4 _+ Z
The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising
0 k0 z% M1 I* s: k5.39.217.76and 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
1 p1 T9 L5 {/ G5.39.217.76as a pyroclastic flow.
1 p1 [, c8 X s: g- R/ G3 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。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。" @* U$ ^" V3 x6 \) D) _0 C
This photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up:5.39.217.76% S# f; W+ h! K8 I
5.39.217.76& w8 X4 F5 U/ G. W
* It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.
& O/ o# E. j; Q4 l4 M* ITVBNOW 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。 * A shockwave from the eruption could have blown a hole in the cloud deck.
* D( i8 v+ Q3 z/ r0 ?! F' d; F * As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.
, ?" v# K: a5 B K7 p公仔箱論壇- { ] `6 f% S3 g/ |; Y: U+ o d

' p- W T( n) E" b4 N" k' p A1 T# _+ d0 M
Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet.
, r4 W; `" f( e7 a+ ^5.39.217.76It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
- {- c1 [6 o: P the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.
2 K- Y; ^/ S# Q8 v% ^* |, B7 ?公仔箱論壇
( u+ h2 Q- B0 Z/ J+ G \. zTVBNOW 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。Redoubt is a 10,200-foot tall stratovolcano 100 miles southwest of Anchorage in the Aleutian Range, west of the Cook Inlet.
* M8 y. g. C5 D6 i( ]" ~
$ [) b2 |) {4 O1 N/ l5.39.217.76
% q7 L6 b+ k' t: r) A/ z7 j4 p8 v
$ t L: D# g" Ytvb now,tvbnow,bttvbMount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
: Y$ ^" ?, l) A/ u9 ]0 k$ V5.39.217.76 the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one
$ s0 X! B8 t" E ?captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
{+ Q$ w) V k& r5.39.217.76this picture are from forest fires ignited by lava.
$ O! b+ P6 c; [ _( jtvb now,tvbnow,bttvb
) u8 ] _5 T, j4 \$ b. t5.39.217.76Etna 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 maytvb now,tvbnow,bttvb0 P) g: i# ?& G$ G$ J6 I0 Q* h7 \
also be the oldest-known active volcano.' I; @' ^# M1 ~! }: h1 ?5 a# d
% l8 \8 T R( _% 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。
1 J. d7 ^- t/ E
3 h! s( m' g# W: i; gA NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high tvb now,tvbnow,bttvb6 c7 o9 n& k# H+ p3 {
and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.
0 E, B% m; {. f0 s, c( _& X5.39.217.76. Z: j d j" K. h& x2 A
tvb now,tvbnow,bttvb7 K n' U6 W7 q. W- x
5.39.217.76/ Z7 l6 m1 a4 D$ n
Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City. 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 o" Y0 Q' E+ K5 Q9 A3 |) a" f
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
! o" C; m: }( i5.39.217.76multiple 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 5.39.217.76+ E; W! I0 {0 T# A# F* D" B v' x) e
of frequent activity. The plume reached heights of around 30,000 feet.
( b0 h9 h' Y9 m1 @6 L. I w公仔箱論壇5.39.217.76% n5 S, M+ k+ {8 N" l+ j4 X

2 _% I; X) w, H& A2 p4 T
5 Y5 y, B3 l Z4 K: b6 A, vtvb now,tvbnow,bttvb
' v2 O2 ~. F2 A9 n- h5 }$ {
0 Z4 D) @7 {8 S0 }4 ~$ itvb now,tvbnow,bttvbThis eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the
. S" l4 r- X: mtvb now,tvbnow,bttvbwest coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.
4 j1 a! k: C" C1 ~3 ^" w5.39.217.76
" @8 P. D, `; G1 ^Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic
; G: `3 b1 ?( M/ ?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。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.5.39.217.762 n( v8 G/ \% Y
5.39.217.761 C% d7 v# U! i/ E" b
tvb now,tvbnow,bttvb, l# p1 A% J- |6 n% ]
6 A; z+ k; O' }1 H; R+ {0 R
This 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6 R3 T& k& J4 `( b( s0 r
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 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。0 Q+ }3 W2 q Q) ?4 Y
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
; W! d9 n f0 R& N) otvb now,tvbnow,bttvbstationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
% m" Q3 J. p' Z9 W8 Y. d btvb now,tvbnow,bttvb8 m( y; a1 D1 A% D; a2 o
+ P/ M1 W, ]! \1 @, S8 y! m1 R1 F
8 F0 @2 ~/ M& S U/ t6 r
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.
% V$ |' i# a0 e* g: ?# |公仔箱論壇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
. H1 l. I3 [, |9 k公仔箱論壇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,
! z9 p1 R( J5 C E g+ z- ltvb now,tvbnow,bttvbcausing avalanches of debris into the crater. |