[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.