Home
登录
注册
学习内容
Loading...
听力练习
听力练习
/
Video
/
MinuteEarth
/
How To Kill A Volcano
How To Kill A Volcano
选择学习模式:
查看字幕
选词
重写单词
字幕 (81)
0:00
Volcanoes are one of the most powerful
0:01
forces on Earth. Their lava can destroy
0:04
cities and their ash clouds can blot out
0:05
the sun.
0:06
>> [music]
0:06
>> And there is basically nothing we can do
0:08
to make sure a volcano will never erupt
0:10
again,
0:11
>> [music]
0:11
>> except wait for it to die. So, while we
0:14
wait, what is it exactly that kills a
0:17
volcano? Hi, I'm Cameron and this is
0:20
Minute [music] Earth. There are three
0:21
main ways a volcano can die, and the
0:23
first is if its supply of magma fizzles
0:26
out. The pushing together or pulling
0:28
apart of tectonic plates can cause magma
0:30
to form. But when those plates fuse
0:32
[music] together, the magma forming
0:33
activity stops, snuffing out the
0:35
volcano. Poland's Kaczawskie Hills and
0:38
Foothills has a whole national park
0:40
devoted to volcanoes that suffered this
0:41
[music] fate. Locals call it the land of
0:44
extinct volcanoes. The second way a
0:46
volcano can die is if it gets dragged
0:48
away from its magma supply. Sometimes
0:50
weird conditions in specific places can
0:53
melt the mantle, sending up a plume of
0:54
melting mantle rock known as a hotspot
0:57
that pools beneath the crust and can
0:59
birth a volcano. That hotspot itself
1:01
doesn't ever move, but the Earth's crust
1:03
above it does. So, the volcano will
1:05
eventually leave its magma supply
1:07
behind. But since the hotspot itself is
1:09
still there, when one volcano dies in
1:12
this way, a new one might form next to
1:14
it, and then a new one forms next to
1:15
that, and so on. The Hawaiian Islands,
1:18
for instance, are the newest volcanoes
1:19
[music] formed by a hotspot that has
1:21
left a trail of dead volcanoes that
1:23
stretches all the way to Russia. The
1:25
third way a volcano can die is if it
1:26
gets clogged. Like if conditions in the
1:29
mantle change and the magma flow slows
1:30
down, the magma that's already in the
1:32
volcano's vents can cool, hardening into
1:34
a giant plug.
1:35
>> [music]
1:35
>> 50 million years later, that plug might
1:37
be all that's left of the volcano. Or,
1:39
if the volcano's vents somehow get
1:41
damaged, the magma might not be able to
1:43
escape. In these cases, the remaining
1:45
magma will often find its way to a
1:47
different spot nearby where it can
1:49
escape. [music]
1:50
That's likely what happened when, in a
1:51
spectacular eruption, the largest ever
1:54
actually, a volcano called Toba clogged
1:56
itself. Evidence suggests that the magma
1:58
from its chamber got rerouted to nearby
2:01
Sinabung, which is still active today.
2:03
Of course, it's really, really hard to
2:06
tell exactly what's going on underneath
2:07
a volcano, so we're not always sure what
2:10
has happened to a volcano. In fact,
2:12
sometimes it's hard to tell whether a
2:14
volcano is actually dead. Uturuncu in
2:17
Bolivia hasn't erupted [music] in
2:19
250,000 years, so scientists assumed it
2:22
was long gone. But recently, it started
2:24
rumbling again, suggesting the
2:26
possibility of future volcanic activity.
2:28
>> [music]
2:28
>> It turns out that Uturuncu and other
2:31
quiet volcanoes like it might not be
2:33
dead after all. Instead, they could be
2:36
taking magnifcently [music] long naps.
