One of the most violent but beautiful reminders that we live on ageologically restless planet are volcanic 5.39.217.760 W% G7 V8 D. @8 c
eruptions. Around 550volcanoes have erupted at least once in historic times, and around 50or 60 are
! ?( p, K# R g3 I5 W公仔箱論壇active each year. On any given day, as many as 10 volcanoesmay be spewing ash or lava somewhere on Earth.
9 p( s$ i/ d0 u1 @5 s0 Y3 ZSome volcanoes, such as Mount Etna in Italy, erupt almost constantlyfor years on end. Others, like Mount St. Helens,
* n; ^( ]2 K2 k5.39.217.76erupt rarely andsometimes extremely destructively. Like Etna and Mount St. Helens, manyof the most dangerous
# x, U% y0 _: Yand explosive erupters are stratovolcanoes, whichare made of layers of ash and lava from previous eruptions. ) W0 [% ]! V- K9 ^/ ?
They tendto be steep-sided cone-shaped volcanoes and often rise strikingly abovethe surrounding landscape.
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Many of the stunning images of eruptions captured from space are ofviolent stratovolcanoes, such as the one above tvb now,tvbnow,bttvb& N. t# y7 C* g: F0 A
of Kliuchevskoi, themost active volcano on Russia’s Kamchatka peninsula. The image abovewas
; Z7 ?2 {# H$ c( |" C7 y- 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。taken by astronauts on the space shuttle Endeavour in 1994, as an eruption was just getting underway. The ash 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 B- }8 ]! O2 B0 }% W7 U
plume reached as high as 50,000 feet.. t. v" @/ C$ Y# N* E
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Augustine Volcano is a 4,100-foot-tall, 7-mile-wide stratovolcano. This eruption was captured by NASA’s Terra
" Y. F- U, c- U: ]- U, B$ Y1 u# W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 5.39.217.76" B1 P( M5 O6 J2 M5 |/ I; L
years. The island’s jagged edges were created by massive avalanches.
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2 @ G' q# {$ h( r7 `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。Augustine lies in the Cook Inlet at the eastern end of the Aleutian trench which marks the northernmost portion of the Pacific Ring 9 N' D9 Z& \# }
of Fire. Volcanic activity here is caused by the subduction of the Pacific plate beneath the North American plate. As the wet
' W2 i5 K! N$ C0 p4 A% U' ~; ^) L5.39.217.76ocean crust descends into the molten mantle below, superheated water is squeezed out and rises up to melt the bottom of
) `' g p4 N5 K* T/ X8 @5.39.217.76the continental crust, creating magma that drives the volcanic eruptions
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Astronauts aboard the International Space Station caught a lucky glimpse of the start of this eruption of Sarychev Volcano
6 U5 @# v/ E& _in the Kuril Islands, northeast of Japan, on June 12, 2009. This was the volcano’s first eruption in 30 years.
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The smooth white cloud, known as a pileus cloud, topping the eruption column may be made of water condensation caused by rising 7 u2 {! E1 L2 r/ l: u
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
6 d8 x: x% v$ \6 C: D) ~5.39.217.76as a pyroclastic flow.3 _! g" a/ w( b; r& U0 h% C
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This photo sparked a debate among scientists about what caused the hole in the clouds above the eruption. Three possible options came up:0 h2 D. y; S) f7 G' i
6 `9 k7 a$ Q& M3 x; I公仔箱論壇 * It could have nothing to do with the eruption and simply be caused by the contrast in temperatures between the ocean and the island.5.39.217.769 o- K" P- U7 a) i. R% h ]
* A shockwave from the eruption could have blown a hole in the cloud deck.
7 `6 [6 G: |4 F: ]. [ * As the plume rose, air flowed downward along the sides and became warmer and evaporated the clouds.公仔箱論壇! N7 m6 I( p: R; p( x$ R
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Alaska’s Redoubt Volcano erupted five times in one night this year after almost three decades of relative quiet. 5.39.217.76+ G) P, b6 \8 }% a
It continued erupting on and off for weeks afterward. This image was taken by the commercial satellite GeoEye-1 on March 30 when
) {1 o% t1 P- P- ?4 R5.39.217.76 the ash reached heights of 27,000 feet. The volcano’s alert level is still “advisory,” and the aviation color code is yellow.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 d' n( U B0 ^4 _" w5 t
6 i3 d+ i8 k) [3 JRedoubt is a 10,200-foot tall stratovolcano 100 miles southwest of Anchorage in the Aleutian Range, west of the Cook Inlet.tvb now,tvbnow,bttvb9 p/ n0 N2 f; w4 ^& C
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Mount Etna is the second tallest volcano in Europe, at almost 11,000 feet. It is one of the most active volcanoes in
, e6 [ X; ?- H# K the world and is erupting nearly continuously. It is no surprise that there are many great photos of this volcano erupting, including this one
/ H* Z3 {* k# |" ~ `: _公仔箱論壇captured by astronauts on the International Space Station in 2002. The lighter colored plumes of smoke on the slope of the volcano in
4 |3 |5 E1 u) _% I公仔箱論壇this picture are from forest fires ignited by lava.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。' n7 ]# m' D+ ^$ g/ B9 f4 n/ I4 {
+ \, P5 Y& u0 k3 X% }, I. btvb now,tvbnow,bttvbEtna 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 mayTVBNOW 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 t5 N& ?# f' N/ e3 V
also be the oldest-known active volcano.公仔箱論壇. A) x! c9 |, |
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A NASA astronaut spotted this eruption of Cleveland Volcano from the International Space Station in 2006. The volcano is 5,700 feet high 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 M- u# \: ?% k
and claimed the only known eruption-related death in Alaska’s Aleutian Islands in 1944. Its symmetrical, cone shape is typical of stratovolcanoes.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。 Y/ `: Z* ~, ^6 ~* a
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Popoépetcatl, which means “smoking mountain” in the Aztec language, is a very active volcano just 44 miles outside Mexico City. 公仔箱論壇2 k* y4 w5 x3 u1 V1 \2 H- O1 S1 _
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
X, _+ N! L- e1 uTVBNOW 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 5.39.217.768 S9 t$ z* b9 D0 g
of frequent activity. The plume reached heights of around 30,000 feet.
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* E$ U1 z1 m W5.39.217.76This eruption of Chaitén caldera in Chile was photographed from the International Space Station in May 2008. Volcanism along the 公仔箱論壇" r' s9 y1 m7 X; i6 a
west coast of South America is the result of subduction of the oceanic Nazca plate beneath the South American plate.
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Chaitén was last active more than 9,000 years ago. The violent 2008 eruption inundated the small coastal town of Chaitén with ash, pyroclastic 4 A# J R8 D$ I; f& r4 E; I& y
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.
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5 ]$ n: D# a+ t. Gtvb now,tvbnow,bttvbThis image of the Sierra Negra volcano in the Galapagos Islands was taken by NASA’s Terra satellite in 2006. Sierra Negra 5.39.217.76, U# b- F# f6 A0 c2 P
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
2 ^* m: y& r/ u; ~. k6 x- X5.39.217.76formed 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
: l5 j+ [( A: q* sTVBNOW 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。stationary hot spot, volcanoes are formed. The Hawaiian Islands were formed — and continue forming — the same way.
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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. & |+ X+ y' _; ^6 a4 P
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
1 ? P# L* ` s; Z4 L/ A0 ^7 } OTVBNOW 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。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,
q/ J2 o2 {7 B公仔箱論壇causing avalanches of debris into the crater. |