The rate at which icebergs drift and disintegrate influences the risk of collisions with high-latitude hydrocarbon infrastructure and shipping1, the extent of zones of nutrient-enhanced carbon sequestration2,3, and the interpretation of palaeoclimate indicators such as ice-rafted debris4. Although iceberg drift-decay models exist5, our mechanical understanding of iceberg disintegration remains unable to explain the size-frequency distributions of icebergs commonly observed; most notably the discrepancy between the power-law distributed icebergs sizes observed at glacial calving fronts6 and the lognormal iceberg-size distributions observed globally within open waters7,8. Although it has been speculated that the lognormal distribution of iceberg sizes observed away from glacial calving fronts is the product of the mechanisms by which icebergs fracture and disintegrate7, the absence of appropriate methods with which to study free-floating iceberg disintegrations has limited efforts to study the mechanics of this phenomenon.
If an accurate understanding of the mechanisms of iceberg breakup could be obtained, numerical models could be used to predict the expected distribution of iceberg sizes resulting from the disintegration process, their trajectories, and their longevity; information which informs risk to shipping and delineates the areas influenced by the delivery of ice-rafted debris and nutrients. One such modelling approach is the use of probabilistic magnitude-frequency scaling laws, which provide a means to quantify the likelihood that an event of a given magnitude will occur over time or, in the context of icebergs, that an iceberg of known dimensions will be produced as a result of the disintegration process. This approach has been widely applied in attempts to forecast the occurrence of natural hazards such as rockfalls27 and landslides28. We therefore apply a probabilistic scaling approach to capture, characterise and model the manner in which icebergs calved from Jakobshavn Isbræ disintegrate as they drift through the Vaigat Strait towards Baffin Bay, West Greenland, determined through passive seismic monitoring (Fig. 1). Based on a lognormal distribution of energy released by iceberg cracking and calving, we conclude that the lognormality associated with free-floating iceberg size-frequency distributions is a product of the process of iceberg disintegration and dimensional reductions through melting after their initial calving. We propose that the emergence of a dominant set of iceberg-degradation processes over space transforms the characteristic distribution of iceberg dimensions from a power-law at glacial calving fronts to a lognormal distribution as icebergs drift towards the open ocean.
Satellite images of the often-cloudy region show the breakup that occurred between January 19-21, 2022. Sea ice cracked and drifted away from the coast, along with icebergs from the fronts of Crane Glacier and its neighbors to the north and south. Therefore, strong and warm winds were likely to play a decisive role in triggering the shattering of the ice shelf.
It's finally adrift. When the Larsen C Ice Shelf calved yesterday, it sent one of the largest icebergs ever recorded slipping into a sea frosted with smaller chunks of ice. It marked the end of a decadeslong splintering first seen by satellites in the 1960s. The crack stayed small for years until, in 2014, it began racing across the Antarctic ice.
While this is the second major calving event A-68 has seen since it broke free of the Larsen C Ice Shelf in July 2017, the crack could represent the beginning of the end for the iceberg, glaciologist Adrian Luckman told BBC News.
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Face - The end of a drift, crosscut or stope inwhich work is taking place.Fault - A break in the Earth's crust caused by tectonic forces which havemoved the rock on one side with respect to the other.Feldspar - A group of common rock-forming minerals that includesmicrocline, orthoclase, plagioclase and others.Felsic - Term used to describe light-colored rocks containing feldspar,feldspathoids and silica.Ferrous - Containing iron.Fine gold - Fineness is the proportion of pure gold or silver in jewelryor bullion expressed in parts per thousand. Thus, 925 fine gold indicates 925parts out of 1,000, or 92.5% is pure gold.Fissure - An extensive crack, break or fracture in rocks.Fixed Assets - Possessions such as buildings, machinery and land which,as opposed to current assets, are unlikely to be converted into cash during thenormal business cycle.Float - Pieces of rock that have been broken off and moved from theiroriginal location by natural forces such as frost or glacial action.Flotation - A milling process in which valuable mineral particles areinduced to become attached to bubbles and float as others sink. Flowsheet - An illustration showing the sequence of operations, step bystep, by which ore is treated in a milling, concentration or smelting process.Flow-through shares - Shares in an exploration company that allow the taxdeduction or credits for mineral exploration to be passed to the investor.Flux - A chemical substance that reacts with gangue minerals to formslags, which are liquid at furnace temperature and low enough in density tofloat on the molten bath of metal or matte.Fluxgate magnetometer - An instrument used in geophysics to measure totalmagnetic field.Fold - Any bending or wrinkling of rock strata.Footwall - The rock on the underside of a vein or ore structure.Forward contract - The sale or purchase of a commodity for delivery at aspecified future date.Fracture - A break in the rock, the opening of which allowsmineral-bearing solutions to enter. A \"cross-fracture\" is a minor breakextending at more-or-less right angles to the direction of the principalfractures.Free milling - Ores of gold or silver from which the precious metals canbe recovered by concentrating methods without resorting to pressure leaching orother chemical treatment.
Frost wedging, also called ice wedging, uses the power of expanding ice to break apart rocks. Water works its way into various cracks, voids, and crevices. As the water freezes, it expands with great force, exploiting any weaknesses. When ice melts, the liquid water moves further into the widened spaces. Repeated cycles of freezing and melting eventually pry the rocks apart. The cycles can occur daily when fluctuations of temperature between day and night go from freezing to melting. 1e1e36bf2d