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In a first , researchers have record countless " ice quakes " that sporadically shake the Greenland Ice Sheet . These quakes may explain the jerky way that the island ’s frozen rivers move downstream toward the ocean , the scientist say .
Researchers notice these temblor by lowering a fiber - optic cable system into a 1.7 - nautical mile - abstruse ( 2.7 kilometers ) borehole in the Northeast Greenland Ice Stream — Greenland ’s magnanimous frozen river that serve as the main artery through which ice isdischarged from the ice sheet ’s interiorinto the North Atlantic Ocean .
Researchers recorded ice quakes in the Greenland Ice Sheet by lowering a fiber-optic cable down a borehole. Pictured above is a tunnel that leads to the borehole.
like to earthquake , ice temblor are seismal result that can happen in frappe when it fractures and two slab grind against each other .
deoxyephedrine quake in Greenland have gone undetected until now because they are bar from reaching the surface by a level of volcanic mote bury 2,950 foot ( 900 meters ) beneath the sparkler , the researchers said in astatement . These atom rise from a Brobdingnagian eructation of Mount Mazama , in what is now Oregon , about 7,700 years ago , they said .
Related : Greenland ’s ice sheet of paper — the second biggest in the earth — is cracking open at alarming speed , scientists discover
The researchers set up camp on the Northeast Greenland Ice Stream, the biggest frozen river on the island.
Not only do volcanic speck prevent seismic waves from traveling to the surface , but they may also be flat creditworthy for the quakes , Andreas Fichtner , a prof of geophysical science at the Swiss Federal Institute of Technology ( ETH ) in Zurich and the lead-in author of a new cogitation published Feb. 6 in the journalScience , said in the financial statement . The methamphetamine hydrochloride quakes probably begin from dross in the ice , such as sulphate and other particles , which may destabilize the water ice and lead to the formation of pocket-sized cracks .
" We were amaze by this previously obscure relationship between the dynamics of an ice current and volcanic eruptions , " Fichtner say .
Ice seism can trigger other ice quakes like dominoes , and thereby pass around horizontally over gravid distances , according to the statement .
Andreas Fichtner and his colleagues recorded seismic signals with a fiber-optic cable continuously for 14 hours.
Rethinking how ice streams move
research worker are interested in ice flow — and the role ice quakes play in the way these streams move ice — because they dump big amounts of frosting from glaciers into the sea , contributing to ocean level ascension . Uncertainties about how exactly frappe flow enrapture their cargo lead to misplay in computer theoretical account that help oneself scientists valuate the future impact ofclimate change .
antecedently , scientist think that the ice only flux tardily through these rivers like blockheaded honey . But the young finding , along with old research , has force scientist to rethink the way chicken feed moves .
" The assumption that chicken feed streams only flow like glutinous love is no longer well-founded , " Fichtner said .
Instead , the new data confirm that tiny earthquake deep inside the Greenland Ice Sheet cause ice stream to " also move with a constant control stick - slip motion , " Fichtner say .
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The Greenland Ice Sheet is the turgid ice weather sheet in the Northern Hemisphere , compensate approximately 80 % of Greenland ’s landmass . Meltwater from the Greenland Ice Sheet is already the liberal global source of sea level rise , account for a 0.6 - inch(1 centimeter ) step-up since the 1990s . Scientists approximate there is enough icing lock inside Greenland toraise ocean level by 23 feet(7 m ) .
" The fact that we ’ve now discovered these methamphetamine quakes is a fundamental footprint towards gain a better understanding of the contortion of ice flow on minuscule scale , " study co - authorOlaf Eisen , a prof of glaciology at the Alfred Wegener Institute for Polar and Marine Research in Germany , say in the assertion .
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