One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic
: }; \( k& G* [0 {6 \! P- _5.39.217.77eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are 5.39.217.77/ U( K/ [. Q% I# h" J$ F% i' y
active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
; z* d8 ^3 X2 M! t" i( VSome volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
8 y& T5 P* F- x6 d' merupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
) ~/ U" A% H' J, g+ m) mand explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions.
& Y6 ^2 P4 h& n, k3 {9 vtvb now,tvbnow,bttvbThey tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.
* G2 u5 _- d: S0 Y公仔箱論壇5.39.217.77. ]% F( N: r) f/ Y# O! n& d
7 Q$ j! M( R, V( mtvb 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。4 |9 K0 c+ m: H# |& b
Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above
' U, r r3 O/ g5 `) VTVBNOW 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 Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
* M5 J/ I2 B) Ntaken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash
1 ?1 \/ S. V$ m; E3 Vplume reached as high as 50,000 feet.
) N/ ^- `9 _( ^0 }! y/ [* Q# ^tvb now,tvbnow,bttvb
( W4 ?+ f( U% w* K/ L
7 _: s! z: f% N6 R5.39.217.77) [/ d, T# D7 W" B& q3 e" _/ J
Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
8 X. A, c8 }9 ?% @9 vtvb 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 \& ~( u! w6 ] Z
years. The island’s jagged edges were created by massive avalanches.7 m* y/ c8 R0 ?) |3 G2 X- C
( q. H t$ F! e) A1 aTVBNOW 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 公仔箱論壇& S; A" p5 R3 a" t9 Y& a
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet , C8 R9 ]; M a j; q. U, I
ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
4 U+ K7 d0 {1 Y d8 vTVBNOW 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 continental crust, creating magma that drives the volcanic eruptions
p/ u' Q8 c/ U7 v& }tvb now,tvbnow,bttvb! c+ ?" C" z- ?( k4 j; R
 / g: N: d; {* a; e* b# ?2 I
7 X# H+ e- i# i! R, A0 Z
Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano , ~/ n- h8 |# F* w/ G
in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.
2 V, ]7 p# i5 x6 q, O7 S: j公仔箱論壇5.39.217.77# q" ~' U1 a6 w; b9 c; \
The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising
) S H8 e3 r3 Z9 h( f3 H. G) q/ Wand 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
2 V) N& {: g& |, t9 X6 z; j# 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。as a pyroclastic flow.tvb now,tvbnow,bttvb4 y" J t/ ~* x6 A" t
7 J+ A2 a2 l; C8 F& O: P* W
This 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。% w7 f7 d! G" f" h2 C1 Q, C8 G+ n! n
' R' r. Z6 Y4 N7 ytvb now,tvbnow,bttvb * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.
4 z* S/ m3 ^* I+ E o * A shockwave from the eruption could have blown a hole in the cloud deck.
, g: { D0 Y. j% W# i" L公仔箱論壇 * As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.
/ r( S! P; Z% [; v, O; Q公仔箱論壇公仔箱論壇4 ~& K9 w( F, l3 s" X% l* J! f
& b. O% U) G: v+ }. a( J9 Y( M: [& ~6 ^' u
Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet. 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。; D+ X5 @8 ?8 D6 N
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
7 d% u( h1 O' K1 j the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.
' \" W( ~2 |, u" P4 r1 D5.39.217.77
3 m. R0 k! ~' A- ~% JTVBNOW 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.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。" b( o1 }: m: }- L* h5 f$ F
, k. w- w' ]" ?
 % ?$ A5 E, k6 ^
7 m9 F b m& J3 Stvb 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
M/ j& r3 ^" F' | the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one 公仔箱論壇5 D+ |& f; f* [! S0 F+ D
captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
* o, b" e& {; ^: w# M5.39.217.77this picture are from forest fires ignited by lava.
9 y9 U- ~% t, n! \$ q+ I) }( z% ]tvb now,tvbnow,bttvb
/ V9 ~2 o4 [* t+ ^6 }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
$ N7 I6 [0 L( }5 [0 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。also be the oldest-known active volcano.* G9 i8 z. G+ o
5.39.217.77 A* h( Z1 i0 C! V+ c% c0 _4 a
 公仔箱論壇( A/ T+ D b3 J9 p1 n
# o$ w4 C, Z6 `8 Q9 B+ u
A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high
. A. |( f+ P. n7 g: pand claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.
_5 f, \/ `2 V+ D! b5.39.217.77TVBNOW 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# r8 U& `% L3 V
0 F/ H! L- x3 ~/ X
! B9 t) v5 W* I3 h+ YPopoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City. 5.39.217.77 |0 d- {2 P% r0 |/ q
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 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 l- J& q. @0 T5 _; Z7 s
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
e6 t2 m- x# |' Pof frequent activity. The plume reached heights of around 30,000 feet.
]' p5 ?6 z4 C0 b0 w8 M- r' Jtvb now,tvbnow,bttvb公仔箱論壇0 T! l& ? \% n' R" o7 E
 公仔箱論壇2 T8 k3 w. _6 K9 x. o$ u
7 o5 O \7 ^. Q/ o' ]9 ]5.39.217.77 $ }% y( S7 N+ 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。+ f$ u: O9 O1 w% X
This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the 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 H/ p' f) |. h3 u8 q# z; N' b
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.tvb now,tvbnow,bttvb$ d+ s0 Y9 Q! a4 s$ f8 }: V
0 A7 @ R n9 ^; _% m. N4 a7 mChaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic 5.39.217.774 q- L. N% |4 F0 p% e0 l; @
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 g* k) Q" b2 r% X) q6 G6 B公仔箱論壇
) J% c- g/ Y: W7 C" t' t$ Dtvb now,tvbnow,bttvb
. N. U' I0 v( g& z! C* X
1 L+ ~& b: s& a9 T$ X) s$ z公仔箱論壇This image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra 5.39.217.773 G/ h5 q4 e+ h/ e% @
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 5.39.217.77$ K" `% [+ Y+ a
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 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。6 A% `7 ? @- b. p; C
stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.- U" r( C- `6 Y4 z) R0 p: Q8 L: ^
5.39.217.773 |9 H8 o% C4 D* W4 I! Q% S
0 o/ ]7 m- H& |- P/ {$ A
" N: z6 R" g7 ~公仔箱論壇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. / z& d0 U+ ]9 V1 O
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
( e [" T [" @tvb now,tvbnow,bttvbthat 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, 6 `" B) [. q. _
causing avalanches of debris into the crater. |
發表於 2009-12-22 08:34 AM
| 
