Posts Tagged "greenland"

Earthquake in Greenland Triggers Fatal Landslide-Induced Tsunami

Posted by on Jun 28, 2017 in All Posts, Featured Posts, News | 0 comments

Earthquake in Greenland Triggers Fatal Landslide-Induced Tsunami

Spread the News:ShareThis post, written by David Jacobson, appeared earlier this month on the website Temblor. It has been lightly edited. A M=4.1 earthquake which took place on June 17 on Greenland’s western coast caused a massive landslide, triggering a tsunami that inundated small settlements on the coast. At this stage, four people are feared to have died, nine others were injured, and 11 buildings were destroyed. In the hardest hit village, Nuugaatsiag, which is home to around 100 people, 40 people were evacuated to Nuugaatsiag, the eleventh-largest town in Greenland. While this earthquake appears to be tectonic in nature, according to Meredith Nettles of the Lamont-Doherty Earth Observatory at Columbia University, Greenland also experiences what are known as glacial earthquakes. Glacial earthquakes are a relatively new class of seismic event, often linked to the calving of large outlet glaciers. While this type of event has also been observed in Antarctica, the majority have been recorded off the coast of Greenland, and show a strong seasonality, with most of them occurring late in the summer. Because glacial earthquakes have a different mechanism than normal earthquakes, standard earthquake monitoring techniques cannot be used to detect them, which explains why they were not known about until 2003. Additionally, while a tectonic M=5 quake typically lasts about 2 seconds, a comparable M=5 glacial earthquake can emit long-period (greater than 30 seconds) seismic waves. It is because of this that they have a separate classification. In order for a glacial earthquake to occur, a large-scale calving event has to take place. When a glacier calves, there is a sudden change in glacial mass and motion. While a glacier is technically a river of ice, meaning it slowly flows downhill, when a large calving event takes place, there is a brief period when horizontal motion reverses. Couple this with a downward deflection of the glacier’s terminus, which causes an upward force on earth’s surface, and you have the recipe for a glacial earthquake. These earthquakes tend to be M=4.6-5.1. Despite the fact that this tectonic quake was by no means large, it was big enough to trigger a massive landslide into the ocean, and the ensuing displacement of water was enough to form a tsunami that devastated parts of Nuugaatsiag. Nettles noted, “The M=4.1 earthquake does not explain the large, long-period (slow) seismic signal detected by seismometers around the globe. The long-period signal appears to be due to a landslide, and the time of the long-period signal is later than the time of the high-frequency (earthquake) signal. It is possible the earthquake triggered the landslide.” What this means is that both the earthquake and landslide generated seismic signals, but that the earthquake signal appeared first, suggesting the quake triggered the slide. The video below shows a view of the landslide, while the photos below show the landslide and the devastation caused by the tsunami.       A helicopter video of the landslide that triggered the deadly tsunami in Greenland:         Spread the...

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Don’t Step on the Crack at Petermann Glacier

Posted by on May 18, 2017 in All Posts, Featured Posts, News, Science | 0 comments

Don’t Step on the Crack at Petermann Glacier

Spread the News:ShareCracks in ice shelves have appeared in disaster movies as ominous signs of global warming. One memorable instance occurs in The Day After Tomorrow when a paleoclimatologist is drilling ice cores at the Larsen Ice Shelf. The shelf breaks apart, leading to a series of cataclysmic climate events that disrupt the North Atlantic Ocean circulation. In July, a real- life crack appeared at Petermann Glacier in Greenland and has been growing steadily ever since. Two scientists, Andreas Muenchow and Keith Nicholls, are investigating the crack and hypothesize that it is caused by an increase in air and ocean temperatures. Petermann Glacier connects the Greenland ice sheet to the Arctic Ocean at 81°N. It is approximately 43 miles long and nearly 10 miles wide. This is not the first crack or full break of ice at Petermann Glacier, according to a Washington Post article by Chris Mooney. Since 2010, entire slabs of the Petermann glacier have broken off. In fact, during two occasions, the glacier lost an area of ice six times the size of Manhattan, according to Mooney. This loss raises enormous concern because the glacier serves to slow down the flow of ice downhill from the Greenland ice sheet into the ocean. For this reason, experts call Petermann a “floodgate.” If the glacier that sits behind Petermann melts, it could raise sea levels by about a foot. A recent paper published in the Geophysical Research Letters describes this type of calving at Petermann as common. The authors explain that it is usually assumed that ocean-ice dynamics are not involved. However, evidence from the Pine Island Glacier in West Antarctica found that ocean forcing can play a role in the melting. Muenchow and Nicholls expect similar dynamics are occurring with Petermann Glacier. They have been on several expeditions to the glacier in order to measure ocean temperatures underneath the shelf itself. They want to see if rising ocean temperatures are also detrimental to the glacier and causing the melting from below. If warm ocean water were melting the base of the glacier, it would only accelerate the destruction of Petermann. While it is extremely difficult to know definitively, they hypothesize Petermann’s river and the channel beneath it are playing a role in the melting. Data from 2015 and 2016 demonstrates that the temperatures of the warm Atlantic layer in the ocean have increased. With both air and ocean temperatures getting warmer, it is unclear how much longer Petermann Glacier will be intact, leaving frightening implications for the melting of the enormous glacier behind it. The crack in the Petermann Glacier and the possible ensuing events show that news from the ice can sometimes be just as scary as the scenes in disaster movies. Spread the...

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Roundup: Game of Thrones, Earth Selfies, and Glacier Safety

Posted by on Mar 20, 2017 in All Posts, Featured Posts, News, Roundup | 0 comments

Roundup: Game of Thrones, Earth Selfies, and Glacier Safety

Spread the News:ShareRoundup: Greenland, Earth Selfies, and Pakistan Game of Thrones Actor Photographs Climate Change From Travel + Leisure: “Google Maps announced a project with Nikolaj Coster-Waldau, ‘Game of Thrones’ actor and U.N. goodwill ambassador, that takes Street View to southern Greenland. Coster-Waldau, who is Danish-born but whose wife is from Greenland and whose family has a home in Greenland’s Igaliku, is focused on increasing awareness of climate change as part of the U.N.’s Sustainable Development Goals. In addition to showing the landscapes of Greenland on Street View, Google also put together a time-lapse showing how snow and ice coverage has changed over recent years.” Read more about their work here. Explore climate change in Greenland with Game of Thrones actor Nikolaj Coster-Waldau (Source: Google Maps/Travel + Leisure).   New Earth Selfies Every Day From Science Magazine: “The San Francisco, California–based company Planet, launched 88 shoebox-sized satellites on a single Indian rocket. These satellites joined dozens already in orbit, bringing the constellation of ‘Doves,’ as these tiny imaging satellites are known, to 144. Six months from now, once the Doves have settled into their prescribed orbits, the company says it will have reached its primary goal: being able to image every point on Earth’s landmass at intervals of 24 hours or less, at resolutions as high as 3.7 meters— good enough to single out large trees. Data from Planet is even enabling the monitoring of glaciers.” Read more about this work here.   Glacier Safety Awareness in Pakistan From Pamir Times: “Mountaineers and researchers from Shimshal Valley trekked across northeastern Pakistan this January, to raise awareness about saving glaciers from a warmer environment. Pakistan is home to the world’s largest glaciers outside of the polar region. The expedition was aimed at monitoring and collecting data to analyze the change in the glaciers due to global warming. The activists hope to inspire people at every level around the world, and Pakistan in particular, to stand up and take some substantial steps in addressing the issues of global warming and climate change.” Read more about the expedition here.   Spread the...

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Roundup: New Islands, New Bacteria, and New Maps

Posted by on Feb 6, 2017 in All Posts, Featured Posts, News, Roundup | 0 comments

Roundup: New Islands, New Bacteria, and New Maps

Spread the News:ShareNew Islands, Bacteria, and Maps Retreating Coronation Glacier Forms New Deltaic Island From American Geophysical Union: “In 1989 Coronation Glacier (Nunavut, Canada) terminates where the main outlet stream has created a pair of small deltaic islands on the northern side of the fjord. In 2016 a new deltaic island has formed near the southern edge of the margin, indicating a shift in the position of the main river outlet emanating from below the glacier, this is also marked by a large plume. The island formed is larger than those observed in 1989 or 1998. The size of the island gives it potential to survive, based on satellite imagery. A visit to the island would be needed to shed light on its potential for enduring. Retreat from 1989 to 2016 has been 1100 meters on the northern side of the fjord and 500 meters on the south side of the fjord. The average retreat of 800 meters in 27 years is over 30 meters/year, much faster than the 1880-1988 period.” Read more about Coronation Glacier here.   Microbial Subglacial Communities in Greenland From Microbial Ecology: “The Watson River drains a portion of the southwest Greenland ice sheet, transporting microbial communities from subglacial environments to a delta at the head of Søndre Strømfjord. This study investigates the potential activity and community shifts of glacial microbiota deposited and buried under layers of sediments within the river delta. A long-term (12-month) incubation experiment was established using Watson River delta sediment under anaerobic conditions, with and without carbon dioxide/hydrogen enrichment. The results highlight the need for further investigations into the fate of subglacial microbiota within downstream environments.” Learn more about subglacial microbial communities here.   Improving Glacier Bed Topography Mapping From Oceanography: “Melting of the Greenland Ice Sheet has the potential to raise sea level by 7.36 meters and is already contributing to global sea level rise at a rate higher than 1 milimeter/year. Computer models are our best tools to make projections of the mass balance of Greenland over the next centuries, but these models rely on bed topography data that remain poorly constrained near glacier termini. We combine here for the first time mass conservation glacier bed mapping and newly collected bathymetry data from NASA’s Oceans Melting Greenland (OMG) to evaluate and improve descriptions of bed topography under grounded ice near glacier termini, where it matters most for improving the reliability of ice sheet models.” Read more about NASA’s Oceans Melting Greenland data here.   Spread the...

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Roundup: Sediments, Swamps and Sea Levels

Posted by on Jan 9, 2017 in All Posts, Featured Posts, Roundup | 0 comments

Roundup: Sediments, Swamps and Sea Levels

Spread the News:ShareRoundup: High Arctic, Peru, and Global Seas   Suspended Sediment in a High-Arctic River From Science of The Total Environment: “Quantifying fluxes [the action of flowing] of water, sediment and dissolved compounds through Arctic rivers is important for linking the glacial, terrestrial and marine ecosystems and to quantify the impact of a warming climate… This study uses a 8-years data set (2005–2012) of daily measurements from the high-Artic Zackenberg River in Northeast Greenland to estimate annual suspended sediment fluxes based on four commonly used methods: M1) is the discharge weighted mean and uses direct measurements, while M2-M4) are one uncorrected and two bias-corrected rating curves extrapolating a continuous concentration trace from measured values.”   Read more about suspended sediment fluxes here:     Glacier Recession in Cordillera Blanca From Applied Geography: “Receding mountain glaciers affect the hydrology of downslope ecosystems with consequences for drinking water, agriculture, and hydropower production. Here we combined land cover derived from satellite imagery and other environmental data from the northern Peruvian Andes into a first differencing regression model to assess wetland hydrologic connectivity… The results indicate that there were two primary spatial driving forces of wetland change in Peru’s Cordillera Blanca from 1987 to 1995: 1) loss in glacier area was associated with increased wetland area, controlling for other factors; while 2) an increase in mean annual stream discharge in the previous 12 months increased wetland area.”   Learn more about the study here:     Observation-Based Estimates of Glacier Mass Change From Surveys in Geophysics: “Glaciers have strongly contributed to sea-level rise during the past century and will continue to be an important part of the sea-level budget during the twenty-first century. Here, we review the progress in estimating global glacier mass change from in situ measurements of mass and length changes, remote sensing methods, and mass balance modeling driven by climate observations. For the period before the onset of satellite observations, different strategies to overcome the uncertainty associated with monitoring only a small sample of the world’s glaciers have been developed. These methods now yield estimates generally reconcilable with each other within their respective uncertainty margins. Whereas this is also the case for the recent decades, the greatly increased number of estimates obtained from remote sensing reveals that gravimetry-based methods typically arrive at lower mass loss estimates than the other methods. We suggest that strategies for better interconnecting the different methods are needed to ensure progress and to increase the temporal and spatial detail of reliable glacier mass change estimates.”   Read more about global sea-level rise here:   Spread the...

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