Why are earthquakes so hard to predict? - Jean-Baptiste P. Koehl

1,198,277 views ・ 2019-04-08

TED-Ed


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Prevodilac: Kristina Radosavljević Lektor: Ivana Krivokuća
00:07
In 132 CE,
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Godine 132. naše ere,
00:09
Chinese polymath Zhang Heng
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kineski učenjak Džang Heng
00:12
presented the Han court with his latest invention.
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predstavio je dvoru dinastije Han svoj najnoviji izum.
00:15
This large vase, he claimed,
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Veliku vazu koja je, kako je tvrdio,
00:17
could tell them whenever an earthquake occurred in their kingdom–
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mogla da im kaže kad god bi se dogodio zemljotres u njihovom kraljevstvu,
00:21
including the direction they should send aid.
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uključujući i pravac u kom bi trebalo poslati pomoć.
00:24
The court was somewhat skeptical,
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Dvor je bio pomalo skeptičan,
00:26
especially when the device triggered on a seemingly quiet afternoon.
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pogotovo kada se naprava aktivirala jednog naizgled mirnog popodneva.
00:31
But when messengers came for help days later,
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Ali kada je glasnik došao nekoliko dana kasnije,
00:34
their doubts turned to gratitude.
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njihove sumnje su se pretočile u zahvalnost.
00:36
Today, we no longer rely on pots to identify seismic events,
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Danas ne moramo više da se uzdamo u ćupove
da bismo identifikovali seizmološke aktivnosti,
00:41
but earthquakes still offer a unique challenge to those trying to track them.
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ali zemljotresi i dalje predstavljaju jedinstveni izazov
onima koji pokušavaju da ih otkriju.
00:46
So why are earthquakes so hard to anticipate,
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Zašto je zemljotrese tako teško predvideti,
00:49
and how could we get better at predicting them?
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i kako možemo postati bolji u njihovom predviđanju?
Da bismo odgovorili na ovo pitanje,
00:52
To answer that,
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00:53
we need to understand some theories behind how earthquakes occur.
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moramo razumeti neke teorije o samom nastanku zemljotresa.
00:57
Earth’s crust is made from several vast, jagged slabs of rock
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Zemljina kora je sačinjena od nekoliko velikih, zupčastih stenovitih ploča
01:01
called tectonic plates,
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koje se zovu tektonske ploče
01:03
each riding on a hot, partially molten layer of Earth’s mantle.
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i koje plutaju na vrelom, delimično otopljenom sloju zemljinog omotača.
01:08
This causes the plates to spread very slowly,
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Ovo dovodi do toga da se ploče veoma sporo razdvajaju,
01:11
at anywhere from 1 to 20 centimeters per year.
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od 1 do 20 centimetara godišnje.
01:14
But these tiny movements are powerful enough
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Ali ovi sićušni pokreti su dovoljno moćni
01:17
to cause deep cracks in the interacting plates.
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da stvore duboke pukotine u pločama koje se dodiruju.
01:20
And in unstable zones,
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U nestabilnim zonama,
01:22
the intensifying pressure may ultimately trigger an earthquake.
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sve jači pritisak može na kraju da izazove zemljotres.
01:27
It’s hard enough to monitor these miniscule movements,
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Dovoljno je teško pratiti ove minijaturne pokrete,
01:30
but the factors that turn shifts into seismic events are far more varied.
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a kamoli faktore koji ove promene pretvaraju u seizmološke aktivnosti.
01:35
Different fault lines juxtapose different rocks–
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Različiti rasedi imaju različite stene,
01:38
some of which are stronger–or weaker– under pressure.
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od kojih su neke jače ili slabije kada su pod pritiskom.
01:42
Diverse rocks also react differently to friction and high temperatures.
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Različite stene takođe različito reaguju pri trenju i visokoj temperaturi.
01:46
Some partially melt, and can release lubricating fluids
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Neke se delimično tope i mogu oslobađati tečnost za podmazivanje
01:50
made of superheated minerals
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sačinjenu od otopljenih minerala
01:52
that reduce fault line friction.
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koja umanjuje trenje.
01:54
But some are left dry,
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Ali neke ostaju suve,
01:56
prone to dangerous build-ups of pressure.
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sa opasnom tendencijom akumulacije pritiska.
01:59
And all these faults are subject to varying gravitational forces,
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Svi ovi rasedi su pod dejstvom promenljive gravitacione sile,
02:03
as well as the currents of hot rocks moving throughout Earth’s mantle.
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kao i kretanja užarenih stena koje se kreću kroz zemljin omotač.
02:08
So which of these hidden variables should we be analyzing,
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Dakle, koje od ovih skrivenih varijabli bi trebalo analizirati,
02:11
and how do they fit into our growing prediction toolkit?
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i kako se one uklapaju u naš mehanizam za poboljšanje predviđanja?
02:15
Because some of these forces occur at largely constant rates,
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Kako se neke od ovih sila pojavljuju kao konstanta u većoj meri,
02:19
the behavior of the plates is somewhat cyclical.
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ponašanje ovih ploča je donekle ciklično.
02:23
Today, many of our most reliable clues come from long-term forecasting,
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Danas mnogi naši pouzdani zaključci proističu iz dugoročnog prognoziranja,
02:27
related to when and where earthquakes have previously occurred.
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povezano sa činjenicama gde i kada se zemljotres prethodno dogodio.
02:31
At the scale of millennia,
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Na milenijumskom nivou,
02:33
this allows us to make predictions about when highly active faults,
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ovo nam pomaže da pravimo predviđanja o tome kada će veoma aktivne rasede,
02:37
like the San Andreas,
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kao što je San Andreas,
02:38
are overdue for a massive earthquake.
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pogoditi veliki zemljotres.
02:41
But due to the many variables involved,
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Ali, zbog mnogo uključenih činilaca,
02:44
this method can only predict very loose timeframes.
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ovaj metod može predvideti samo nepouzdan vremenski okvir.
02:47
To predict more imminent events,
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Da bi predvideli događaje u bližoj budućnosti,
02:49
researchers have investigated the vibrations Earth elicits before a quake.
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istraživači ispituju vibracije koje zemlja emituje pre potresa.
02:55
Geologists have long used seismometers
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Geolozi već dugo koriste seizmometre
02:57
to track and map these tiny shifts in the earth’s crust.
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da bi otkrili i mapirali ove male promene u zemljinoj kori.
03:01
And today, most smartphones are also capable
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U današnje vreme, većina pametnih telefona takođe ima sposobnost
03:04
of recording primary seismic waves.
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da detektuje primarne seizmološke talase.
03:07
With a network of phones around the globe,
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Sa mrežom telefona širom sveta,
03:09
scientists could potentially crowdsource a rich,
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naučnici bi možda mogli da sastave bogat
03:12
detailed warning system that alerts people to incoming quakes.
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i detaljan sistem upozorenja koji alarmira ljude o dolazećem potresu.
03:16
Unfortunately, phones might not be able to provide the advance notice needed
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Na žalost, telefoni možda nisu u stanju da unapred pruže potrebno obaveštenje
03:21
to enact safety protocols.
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za sprovođenje bezbedonosnog protokola.
03:23
But such detailed readings would still be useful
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Ali ova precizna očitavanja bi i dalje bila korisna
03:26
for prediction tools like NASA’s Quakesim software,
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kao mehanizam predviđanja, kao što je NASA-in softver „Quakesim”,
03:29
which can use a rigorous blend of geological data
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koji može da koristi izuzetno detaljnu mešavinu geoloških podataka
03:32
to identify regions at risk.
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da identifikuje rizične regione.
03:34
However, recent studies indicate
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Ipak, nedavne studije ukazuju
03:36
the most telling signs of a quake might be invisible to all these sensors.
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da većina predznaka zemljotresa može biti nevidljiva svim tim senzorima.
03:41
In 2011,
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Godine 2011,
03:43
just before an earthquake struck the east coast of Japan,
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pre nego što će zemljotres pogoditi istočnu obalu Japana,
03:46
nearby researchers recorded surprisingly high concentrations
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u blizini su istraživači zabeležili iznenađujuće visoku koncentraciju
03:50
of the radioactive isotope pair: radon and thoron.
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para radioaktivnih izotopa: radona i torona.
03:54
As stress builds up in the crust right before an earthquake,
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Kako se pritisak povećava u zemljinoj kori upravo trenutak pre zemljotresa,
mikropukotine dozvoljavaju ovim gasovima da pobegnu na površinu.
03:58
microfractures allow these gases to escape to the surface.
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04:02
These scientists think that if we built a vast network of radon-thoron detectors
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Ovi naučnici smatraju da, ako napravimo široku mrežu detektora para radon-toron
04:07
in earthquake-prone areas,
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u područjima sklonim zemljotresu,
04:08
it could become a promising warning system–
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to bi mogao postati sistem upozorenja koji obećava -
04:11
potentially predicting quakes a week in advance.
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koji bi možda mogao da predvidi potrese nedelju dana unapred.
04:14
Of course,
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Naravno, nijedna od ovih tehnologija
04:15
none of these technologies would be as helpful
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nije tako korisna kao gledanje duboko u unutrašnjost same zemlje.
04:17
as simply looking deep inside the earth itself.
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04:20
With a deeper view we might be able
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Uz dublji pogled, možda bismo mogli da otkrijemo i predvidimo
04:22
to track and predict large-scale geological changes in real time,
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velike geološke promene u sadašnjem vremenu,
04:26
possibly saving tens of thousands of lives a year.
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spasavajući verovatno na desetine hiljada života godišnje.
04:30
But for now,
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04:30
these technologies can help us prepare and respond quickly to areas in need–
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Za sada,
ove tehnologije nam mogu pomoći da se pripremimo i brzo reagujemo
u područjima gde je to potrebno,
04:35
without waiting for directions from a vase.
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bez čekanja uputstva od vaze.
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