[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:07.52,0:00:09.82,Default,,0000,0000,0000,,In 132 CE,
Dialogue: 0,0:00:09.82,0:00:12.14,Default,,0000,0000,0000,,Chinese polymath Zhang Heng
Dialogue: 0,0:00:12.14,0:00:15.58,Default,,0000,0000,0000,,presented the Han court with \Nhis latest invention.
Dialogue: 0,0:00:15.58,0:00:17.68,Default,,0000,0000,0000,,This large vase, he claimed,
Dialogue: 0,0:00:17.68,0:00:21.32,Default,,0000,0000,0000,,could tell them whenever an earthquake \Noccurred in their kingdom–
Dialogue: 0,0:00:21.32,0:00:24.60,Default,,0000,0000,0000,,including the direction \Nthey should send aid.
Dialogue: 0,0:00:24.60,0:00:26.50,Default,,0000,0000,0000,,The court was somewhat skeptical,
Dialogue: 0,0:00:26.50,0:00:31.00,Default,,0000,0000,0000,,especially when the device triggered \Non a seemingly quiet afternoon.
Dialogue: 0,0:00:31.00,0:00:34.05,Default,,0000,0000,0000,,But when messengers came \Nfor help days later,
Dialogue: 0,0:00:34.05,0:00:36.61,Default,,0000,0000,0000,,their doubts turned to gratitude.
Dialogue: 0,0:00:36.61,0:00:41.11,Default,,0000,0000,0000,,Today, we no longer rely on pots to \Nidentify seismic events,
Dialogue: 0,0:00:41.11,0:00:46.15,Default,,0000,0000,0000,,but earthquakes still offer a unique\Nchallenge to those trying to track them.
Dialogue: 0,0:00:46.15,0:00:49.14,Default,,0000,0000,0000,,So why are earthquakes so \Nhard to anticipate,
Dialogue: 0,0:00:49.14,0:00:52.04,Default,,0000,0000,0000,,and how could we get better \Nat predicting them?
Dialogue: 0,0:00:52.04,0:00:53.10,Default,,0000,0000,0000,,To answer that,
Dialogue: 0,0:00:53.10,0:00:57.54,Default,,0000,0000,0000,,we need to understand some theories \Nbehind how earthquakes occur.
Dialogue: 0,0:00:57.54,0:01:01.79,Default,,0000,0000,0000,,Earth’s crust is made from several vast, \Njagged slabs of rock
Dialogue: 0,0:01:01.79,0:01:03.75,Default,,0000,0000,0000,,called tectonic plates,
Dialogue: 0,0:01:03.75,0:01:08.48,Default,,0000,0000,0000,,each riding on a hot, partially molten\Nlayer of Earth’s mantle.
Dialogue: 0,0:01:08.48,0:01:11.29,Default,,0000,0000,0000,,This causes the plates to \Nspread very slowly,
Dialogue: 0,0:01:11.29,0:01:14.84,Default,,0000,0000,0000,,at anywhere from 1 to 20 \Ncentimeters per year.
Dialogue: 0,0:01:14.84,0:01:17.29,Default,,0000,0000,0000,,But these tiny movements are powerful \Nenough
Dialogue: 0,0:01:17.29,0:01:20.80,Default,,0000,0000,0000,,to cause deep cracks in the\Ninteracting plates.
Dialogue: 0,0:01:20.80,0:01:22.40,Default,,0000,0000,0000,,And in unstable zones,
Dialogue: 0,0:01:22.40,0:01:27.22,Default,,0000,0000,0000,,the intensifying pressure may \Nultimately trigger an earthquake.
Dialogue: 0,0:01:27.22,0:01:30.25,Default,,0000,0000,0000,,It’s hard enough to monitor these \Nminiscule movements,
Dialogue: 0,0:01:30.25,0:01:35.59,Default,,0000,0000,0000,,but the factors that turn shifts into \Nseismic events are far more varied.
Dialogue: 0,0:01:35.59,0:01:38.40,Default,,0000,0000,0000,,Different fault lines juxtapose \Ndifferent rocks–
Dialogue: 0,0:01:38.40,0:01:42.27,Default,,0000,0000,0000,,some of which are stronger–or weaker–\Nunder pressure.
Dialogue: 0,0:01:42.27,0:01:46.98,Default,,0000,0000,0000,,Diverse rocks also react differently to\Nfriction and high temperatures.
Dialogue: 0,0:01:46.98,0:01:50.43,Default,,0000,0000,0000,,Some partially melt, and can release\Nlubricating fluids
Dialogue: 0,0:01:50.43,0:01:52.23,Default,,0000,0000,0000,,made of superheated minerals
Dialogue: 0,0:01:52.23,0:01:54.42,Default,,0000,0000,0000,,that reduce fault line friction.
Dialogue: 0,0:01:54.42,0:01:56.37,Default,,0000,0000,0000,,But some are left dry,
Dialogue: 0,0:01:56.37,0:01:59.14,Default,,0000,0000,0000,,prone to dangerous build-ups of pressure.
Dialogue: 0,0:01:59.14,0:02:03.68,Default,,0000,0000,0000,,And all these faults are subject to \Nvarying gravitational forces,
Dialogue: 0,0:02:03.68,0:02:08.53,Default,,0000,0000,0000,,as well as the currents of hot rocks\Nmoving throughout Earth’s mantle.
Dialogue: 0,0:02:08.53,0:02:11.76,Default,,0000,0000,0000,,So which of these hidden variables \Nshould we be analyzing,
Dialogue: 0,0:02:11.76,0:02:15.96,Default,,0000,0000,0000,,and how do they fit into our \Ngrowing prediction toolkit?
Dialogue: 0,0:02:15.96,0:02:19.83,Default,,0000,0000,0000,,Because some of these forces occur \Nat largely constant rates,
Dialogue: 0,0:02:19.83,0:02:23.16,Default,,0000,0000,0000,,the behavior of the plates \Nis somewhat cyclical.
Dialogue: 0,0:02:23.16,0:02:27.61,Default,,0000,0000,0000,,Today, many of our most reliable clues \Ncome from long-term forecasting,
Dialogue: 0,0:02:27.61,0:02:31.89,Default,,0000,0000,0000,,related to when and where earthquakes \Nhave previously occurred.
Dialogue: 0,0:02:31.89,0:02:33.57,Default,,0000,0000,0000,,At the scale of millennia,
Dialogue: 0,0:02:33.57,0:02:37.53,Default,,0000,0000,0000,,this allows us to make predictions \Nabout when highly active faults,
Dialogue: 0,0:02:37.53,0:02:38.87,Default,,0000,0000,0000,,like the San Andreas,
Dialogue: 0,0:02:38.87,0:02:41.94,Default,,0000,0000,0000,,are overdue for a massive earthquake.
Dialogue: 0,0:02:41.94,0:02:44.19,Default,,0000,0000,0000,,But due to the many variables involved,
Dialogue: 0,0:02:44.19,0:02:47.78,Default,,0000,0000,0000,,this method can only predict \Nvery loose timeframes.
Dialogue: 0,0:02:47.78,0:02:49.69,Default,,0000,0000,0000,,To predict more imminent events,
Dialogue: 0,0:02:49.69,0:02:55.30,Default,,0000,0000,0000,,researchers have investigated the \Nvibrations Earth elicits before a quake.
Dialogue: 0,0:02:55.30,0:02:57.99,Default,,0000,0000,0000,,Geologists have long used seismometers
Dialogue: 0,0:02:57.99,0:03:01.92,Default,,0000,0000,0000,,to track and map these tiny shifts\Nin the earth’s crust.
Dialogue: 0,0:03:01.92,0:03:04.91,Default,,0000,0000,0000,,And today, most smartphones are \Nalso capable
Dialogue: 0,0:03:04.91,0:03:07.67,Default,,0000,0000,0000,,of recording primary seismic waves.
Dialogue: 0,0:03:07.67,0:03:09.74,Default,,0000,0000,0000,,With a network of phones around the globe,
Dialogue: 0,0:03:09.74,0:03:12.68,Default,,0000,0000,0000,,scientists could potentially \Ncrowd source a rich,
Dialogue: 0,0:03:12.68,0:03:16.42,Default,,0000,0000,0000,,detailed warning system that alerts \Npeople to incoming quakes.
Dialogue: 0,0:03:16.96,0:03:21.32,Default,,0000,0000,0000,,Unfortunately, phones might not be able\Nto provide the advance notice needed
Dialogue: 0,0:03:21.32,0:03:23.36,Default,,0000,0000,0000,,to enact safety protocols.
Dialogue: 0,0:03:23.36,0:03:26.08,Default,,0000,0000,0000,,But such detailed readings would still be \Nuseful
Dialogue: 0,0:03:26.08,0:03:29.42,Default,,0000,0000,0000,,for prediction tools like NASA’s \NQuakesim software,
Dialogue: 0,0:03:29.42,0:03:32.26,Default,,0000,0000,0000,,which can use a rigorous blend of \Ngeological data
Dialogue: 0,0:03:32.26,0:03:34.76,Default,,0000,0000,0000,,to identify regions at risk.
Dialogue: 0,0:03:34.76,0:03:36.76,Default,,0000,0000,0000,,However, recent studies indicate
Dialogue: 0,0:03:36.76,0:03:41.64,Default,,0000,0000,0000,,the most telling signs of a quake might be\Ninvisible to all these sensors.
Dialogue: 0,0:03:41.64,0:03:43.00,Default,,0000,0000,0000,,In 2011,
Dialogue: 0,0:03:43.00,0:03:46.26,Default,,0000,0000,0000,,just before an earthquake struck \Nthe east coast of Japan,
Dialogue: 0,0:03:46.26,0:03:50.06,Default,,0000,0000,0000,,nearby researchers recorded surprisingly \Nhigh concentrations
Dialogue: 0,0:03:50.06,0:03:54.42,Default,,0000,0000,0000,,of the radioactive isotope pair \Nradon and thoron.
Dialogue: 0,0:03:54.42,0:03:58.17,Default,,0000,0000,0000,,As stress builds up in the crust right \Nbefore an earthquake,
Dialogue: 0,0:03:58.17,0:04:02.41,Default,,0000,0000,0000,,microfractures allow these gases \Nto escape to the surface.
Dialogue: 0,0:04:02.41,0:04:07.04,Default,,0000,0000,0000,,These scientists think that if we built \Na vast network of radon-thoron detectors
Dialogue: 0,0:04:07.04,0:04:08.99,Default,,0000,0000,0000,,in earthquake-prone areas,
Dialogue: 0,0:04:08.99,0:04:11.52,Default,,0000,0000,0000,,it could become a promising \Nwarning system–
Dialogue: 0,0:04:11.52,0:04:14.53,Default,,0000,0000,0000,,potentially predicting quakes \Na week in advance.
Dialogue: 0,0:04:14.53,0:04:15.23,Default,,0000,0000,0000,,Of course,
Dialogue: 0,0:04:15.23,0:04:17.43,Default,,0000,0000,0000,,none of these technologies \Nwould be as helpful
Dialogue: 0,0:04:17.43,0:04:20.57,Default,,0000,0000,0000,,as simply looking deep inside \Nthe earth itself.
Dialogue: 0,0:04:20.57,0:04:22.24,Default,,0000,0000,0000,,With a deeper view we might be able
Dialogue: 0,0:04:22.24,0:04:26.85,Default,,0000,0000,0000,,to track and predict large-scale \Ngeological changes in real time,
Dialogue: 0,0:04:26.85,0:04:29.73,Default,,0000,0000,0000,,possibly saving tens of thousands \Nof lives a year.
Dialogue: 0,0:04:30.03,0:04:30.87,Default,,0000,0000,0000,,But for now,
Dialogue: 0,0:04:30.87,0:04:35.40,Default,,0000,0000,0000,,these technologies can help us prepare \Nand respond quickly to areas in need–
Dialogue: 0,0:04:35.40,0:04:39.46,Default,,0000,0000,0000,,without waiting for directions \Nfrom a vase.