{"id":32946,"date":"2025-09-23T11:26:07","date_gmt":"2025-09-23T11:26:07","guid":{"rendered":"https:\/\/www.newsbeep.com\/il\/32946\/"},"modified":"2025-09-23T11:26:07","modified_gmt":"2025-09-23T11:26:07","slug":"scientists-placed-a-6-mile-fiber-optic-cable-in-front-of-a-glacier-and-recorded-56000-icebergs-breaking-off","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/il\/32946\/","title":{"rendered":"Scientists placed a 6-mile fiber-optic cable in front of a glacier and recorded 56,000 icebergs breaking off"},"content":{"rendered":"

\"\" <\/a>In the icy waters of southern Greenland, researcher Dominik Gr\u00e4ff, left, and a crew member conduct research off the calving front of the Eqalorutsit Kangilliit Sermiat (EKaS) glacier, visible at left, while the research vessel\u00a0Adolf Jensen\u00a0floats at right. Gr\u00e4ff and his colleagues deployed a fiber-optic cable across the seafloor to record acoustic and temperature changes as the glacier calved. Credit: Julia Schmale.<\/p>\n

On Greenland\u2019s coast, glaciers meet the sea in narrow fjords that have been carved over hundreds of thousands of years. Ice cliffs tower hundreds of meters high.<\/p>\n

At a glacier\u2019s terminus, where those cliffs crash into the waters of the Atlantic, small (bus-sized) chunks of ice slough off all the time. Occasionally, a stadium-sized iceberg plunks into the water.<\/p>\n

All this glacial calving impacts sea level rise and global climate, but there\u2019s a lot that researchers don\u2019t yet know about how calving happens. Now, scientists\u00a0have gotten a detailed look at the whole process<\/a>\u00a0using a fiber-optic cable on the seafloor 500 meters from a glacier\u2019s calving front. The findings were published last month in\u00a0Nature.<\/p>\n

Maneuvering Through the M\u00e9lange<\/p>\n

Physical processes at the calving front control a glacier\u2019s stability, said\u00a0Dominik Gr\u00e4ff<\/a>, a glaciologist at the University of Washington in Seattle who led the new work.<\/p>\n

But gaining access to a glacier\u2019s front can be difficult, and remote sensing methods are able to visualize only the tiny fraction of the ice mass that isn\u2019t submerged. \u201cWe don\u2019t have much idea what\u2019s actually going on below the water,\u201d Gr\u00e4ff said.<\/p>\n

\u201cIt\u2019s always impressive for people to get any observations near the glacier front,\u201d agreed\u00a0David Sutherland<\/a>, a physical oceanographer at the University of Oregon in Eugene who did not contribute to the new paper. Researchers working at the front, he explained, risk losing expensive equipment and have to navigate the m\u00e9lange, a closely packed mix of sea ice and icebergs.<\/p>\n

This was the first time fiber-optic sensing was deployed at a calving front. Unlike other methods, such as remote sensing and the use of submerged seismometers, fiber-optic sensing can capture myriad events across a range of times. \u201cIt can just sense everything,\u201d Sutherland said.<\/p>\n

Gr\u00e4ff and his team dropped a 10-kilometer (6.2-mile) cable on the ocean bottom across the fjord of the Eqalorutsit Kangilliit Sermiat (EKaS) glacier in South Greenland. The maneuver was somewhat tricky. \u201cIf you go too slow, the ice m\u00e9lange that you push open with your vessel [will close] quickly,\u201d Gr\u00e4ff said. \u201cAnd that prevents your cable from sinking down.\u201d<\/p>\n

\"\" <\/a>Julia Schmale, an assistant professor at \u00c9cole Polytechnique F\u00e9d\u00e9rale de Lausanne (left), and Manuela K\u00f6pfli, a University of Washington graduate student in Earth and space science, unspool fiber-optic cable from a large drum on the R\/V\u00a0Adolf Jensen, deploying it to the fjord bottom to record data. Credit: Dominik Gr\u00e4ff\/University of Washington.<\/p>\n

Once the cable was in place, researchers were able to collect a wealth of data.<\/p>\n

Waves, Wakes, and Cracking<\/p>\n

Laser light pulsing through the fiber-optic cable allowed it to function like an entire network of sensors snaking across the fjord.<\/p>\n

Acoustic vibrations associated with calving, for instance, stretched and compressed the cable and changed backscattered\u00a0light signals<\/a>. Measuring these changes is the basis for distributed acoustic sensing, or\u00a0DAS<\/a>.<\/p>\n

In addition to measuring acoustics, fiber optics also allowed researchers to measure how\u00a0light signals<\/a>\u00a0change because of temperature, a technique called distributed temperature sensing, or DTS. DAS and DTS allowed researchers to capture calving events that lasted mere milliseconds.<\/p>\n

During the 3-week experiment at EKaS, the glass fiber captured 56,000 iceberg detachments.<\/p>\n

\"\" <\/a>(1) Initial cracking at EKaS was detected through an acoustic signature traveling through fjord waters. (2) Fractures eventually led to iceberg detachments that emitted seafloor-water interface waves. (3) Detachments caused calving-induced tsunamis at the water surface that caused changes in pressure along the fiber-optic cable. (4) Calving-induced internal gravity waves traveled between layers of fjord water with different temperatures and salinities. (5) Calved-off icebergs drifted away from the glacier terminus, dragging internal wave wakes behind them, agitating the stratified fjord waters and cooling the seafloor. (6) The internal wave wakes caused seafloor currents that generated vibrations in the cable through vortex shedding. (7) Finally, icebergs disintegrated by fracturing, again detected by fiber-optic sensing of acoustic signals. Credit: Gr\u00e4ff et al., 2025,\u00a0https:\/\/doi.org\/10.1038\/s41586-025-09347-7<\/a>,\u00a0CC BY 4.0<\/a><\/p>\n

That volume of observations meant researchers could trace the calving process from start to finish. It began as cracks formed in glacial ice. Sounds associated with the cracking traveled through the fjord and were picked up by the cable. Then icebergs detached from the glacier, creating underwater waves that traveled between the ice and the sediment below. Iceberg detachments also caused small, local tsunamis that could be identified by pressure changes on the cable at the bottom of the fjord.<\/p>\n

In addition to tsunamis and surface waves, the fiber-optic cable was also able to detect internal gravity waves, which travel at the interface between an iceberg\u2019s upper, cold layer of fresh water and the warmer layer of salty seawater below. The EKaS icebergs created wakes as they drifted from the glacier, dragging internal gravity waves behind them and causing circulation in the water. Researchers measured the resulting temperature changes using DTS.<\/p>\n

Finally, the fiber-optic cable captured the sounds of icebergs disintegrating. These signals were similar to the initial sound of cracking in the glacier but instead came from the fjord.<\/p>\n

Wealth of Data<\/p>\n

\u201cThere are very few seismological datasets where, within such a short amount of time, you record so many different phenomena,\u201d said\u00a0Andreas Fichtner<\/a>, a seismologist at ETH Z\u00fcrich in Switzerland who was not part of the work but collaborates with one of the study\u2019s authors. It takes detective work to decode all those signals and assign them to physical processes, he said. \u201cIt\u2019s pretty remarkable.\u201d<\/p>\n

Gr\u00e4ff and the other researchers hope their rich datasets can improve glacial calving models, which often underestimate the melt that occurs below the surface. Sutherland said it\u2019s not yet clear how to incorporate details from the study into such models, however. Researchers will need to connect the observed processes and the amount of ice lost to factors they can easily measure or estimate, such as ocean temperature and ice thickness, he explained. And they\u2019ll need to study the calving process of different glaciers. EKaS sits on bedrock where it meets the sea, for instance, while other glaciers have a floating terminus.<\/p>\n

Still, having a huge set of observations along with information about ocean conditions, which the researchers collected using a suite of other tools, \u201cis pretty powerful,\u201d Sutherland said. \u201cMaybe we can start using this dataset to try to make predictions of when icebergs are going to calve.\u201d<\/p>\n

This article originally appeared in EOS Magazine<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"In the icy waters of southern Greenland, researcher Dominik Gr\u00e4ff, left, and a crew member conduct research off…\n","protected":false},"author":2,"featured_media":32947,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[9918,27822,5330,85,46,141],"class_list":{"0":"post-32946","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-science","8":"tag-fiber-optic","9":"tag-glaciers","10":"tag-greenland","11":"tag-il","12":"tag-israel","13":"tag-science"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/32946","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/comments?post=32946"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/posts\/32946\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media\/32947"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/media?parent=32946"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/categories?post=32946"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/il\/wp-json\/wp\/v2\/tags?post=32946"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}