GeoLog

Publications

May GeoRoundUp: the best of the Earth sciences from around the web

May GeoRoundUp: the best of the Earth sciences from around the web

Drawing inspiration from popular stories on our social media channels, as well as unique and quirky research news, this monthly column aims to bring you the best of the Earth and planetary sciences from around the web.

Major Story

This month the Earth science media has directed its attention towards a pacific island with a particularly volcanic condition. The Kilauea Volcano, an active shield volcano on the southeast corner of the Island of Hawai‘i, erupted on 3 May 2018, following a magnitude 5.0 earthquake that struck the region earlier that day.

Since the eruption, more than two dozen volcanic fissures have emerged, pouring rivers of lava onto the Earth’s surface and spurting fountains of red-hot molten more than 70 metres into the air.  As of today, Kilauea’s eruption has covered about 3534 acres (14.3 square kilometres) of the island in lava, according to the U.S. Geological Survey’s most recent estimates.

The island’s volcanic event has dealt heavy damages to the local community, forcing thousands of locals to evacuate the affected area. On 4 May, the governor of Hawaii, David Ige, declared a local state of emergency, activating military reservists from the National Guard to help with evacuations. Over the month Kilauea’s eruption has engulfed nearby neighborhoods in an oozing layer of lava, overtaking 75 homes, blocking major roads, swallowing up many vehicles, and even briefly threatening a geothermal power plant.

Kilauea’s molten rock, with temperatures at about 1,170 degrees Celsius, is an obvious danger to the local Hawaiian community (one serious injury reported so far). However, the volcanic eruption presents many airborne hazards as well.

In addition to spewing out lava, the Kilauea eruption has projected ballistic blocks, some up to 60 centimeters across, and released clouds of volcanic ash and vog (a volcanic smog of sulfur dioxide and aerosols). The ashfall and gas emissions can create hazardous conditions for travel, produce acid rain as well as cause irritation, headache and respiratory issues.

Kilauea’s lava has steadily marched towards the coast of the Big Island, and recently reached the Pacific Ocean. This interaction of molten rock and ocean water has created plumes of laze (lava haze). Laze is essentially a cloud of acidic steam, mixed with hydrochloric acid and fine particles of volcanic glass. Coming into contact with the toxic vapour can result in eye and skin irritation as well as lung damage.  

Map as of 2:00 p.m. HST, May 31, 2018. Given the dynamic nature of Kīlauea’s lower East Rift Zone eruption, with changing vent locations, fissures starting and stopping, and varying rates of lava effusion, map details shown here are accurate as of the date/time noted. Shaded purple areas indicate lava flows erupted in 1840, 1955, 1960, and 2014-2015. (Image: U.S. Geological Survey)

While residents have been fleeing the the Kilauea-affected region, many scientists have rushed to the Big Island to study the eruption. A swarm of researchers have spent the month recording lava flow activity, measuring seismicity and deformation, monitoring ash plumes by aircraft, and taking samples on foot.

Many volcano scientists have also turned to social media to answer questions from the general public about the recent eruption (like why is the eruption pink? Can you roast a marshmallow with lava?) and bust volcano myths floating online (expect no mega-tsunami from this eruption). The EGU’s own early career scientist representative for the Geochemistry, Mineralogy, Petrology & Volcanology Division, Evgenia Ilyinskaya, was invited to explain some volcano lingo on BBC News.

The volcano’s eruption has been ongoing for weeks, with no immediate end in site. Lava flows are still advancing across the region and volcanic gas emissions remain very high, says the U.S. Geological Survey’s Hawaiian Volcano Observatory. You can stay up to date with the volcano’s latest activity on the agency’s site.  

What you might have missed

A team of scientists from the PolarGAP project have found mountain ranges and three massive canyons underneath Antarctica’s ice using radar technology. These valleys play an important role in channeling ice flow from the centre of the continent towards the ocean, according to the researchers. “If Antarctica thins in a warming climate, as scientists suspect it will, then these channels could accelerate mass towards the ocean, further raising sea-levels,” reports an article from BBC News.

Also in Antarctic news, the Natural Environment Research Council (UK) and the National Science Foundation (US) have announced an ambitious plan to determine the Thwaites Glacier’s risk of collapse. The rapidly melting glacier sheds off 50 billion tons of ice a year, and if Thwaites were to completely go under, the meltwater would contribute more than 80 cm to sea level rise. “Because Thwaites drains the very center of the larger ice sheet system, if it loses enough volume, it could destabilize the rest of the entire West Antarctic Ice Sheet,” according to an article in Scientific American. The research team plans to collect various kinds of data on the glacier and use this information to predict the fate of Thwaites and West Antarctica. The $25-million (USD) joint effort will involve about 100 scientists on eight projects over the course of five years, posing to be one of the largest Antarctic research endeavors undertaken.

Meanwhile, looking out hundreds of millions of kilometres away, scientists have made an interesting discovery about one of Jupiter’s potentially habitable moons.

A team of scientists uncovered a new source of evidence that suggests Europa, one of Jupiter’s moons, may be venting plumes of water vapour above its icy exterior shell. The researchers came across this finding while re-examining data collected by NASA’s Galileo spacecraft, which performed a flyby 200 kilometres above the Europa in 1997. While running the decades old data through today’s more sophisticated computer systems, the research team found a brief, localised bend in the magnetic field, a phenomenon that is now recognised as evidence of water plume presence. These new results have made some scientists more confident that NASA’s Europa Clipper mission, set to launch by 2022, will find plumes on Jupiter’s moon.

Links we liked

The EGU Story

A 2007 paper on global climate zones published in Hydrology and Earth System Sciences, a journal of the European Geosciences Union, has been named the most cited source on Wikipedia, referenced more than 2.8 million times. The Guardian and WIRED reported this story that neither Copernicus Publications nor the Australian authors of the paper were aware of.

EGU training schools offer early career scientists specialist training opportunities they do not normally have access to in their home institutions. Up until 15 August 2018, the Union now welcomes requests for EGU support of training schools in the Earth, planetary or space sciences scheduled for 2019.

In addition, the EGU will now accept proposals for conferences on solar system and planetary processes, as well as on biochemical processes in the Earth system, in line with two new EGU conference series named in honour of two female scientists. The Angioletta Corradini and Mary Anning conferences are to be held every two years with their first editions in 2019 or 2020. The deadline to submit proposals is also 15 August 2018.

And don’t forget! To stay abreast of all the EGU’s events and activities, from highlighting papers published in our open access journals to providing news relating to EGU’s scientific divisions and meetings, including the General Assembly, subscribe to receive our monthly newsletter.

 

Geosciences Column: Extreme snowfall potentially worsened Nepal’s 2015 earthquake-triggered avalanche

Geosciences Column: Extreme snowfall potentially worsened Nepal’s 2015 earthquake-triggered avalanche

Three years ago, an earthquake-induced avalanche and rockfalls buried an entire Nepalese village in ice, stone, and snow. Researchers now think the region’s heavy snowfall from the preceding winter may have intensified the avalanche’s disastrous effect.

The Langtang village, just 70 kilometres from Nepal’s capital Kathmandu, is nestled within a valley under the shadow of the Himalayas. The town was popular amongst trekking tourists, as the surrounding mountains offer breathtaking hiking opportunities.

But in April 2015, a 7.8-magnitude earthquake, also known as the Gorkha earthquake, triggered a massive avalanche and landslides, engulfing the village in debris.

Scientists estimate that the force of the avalanche was half as powerful the Hiroshima atomic bomb. The blast of air generated from the avalanche rushed through the site at more than 300 kilometres per hour, blowing down buildings and uprooting forests.

By the time the debris and wind had settled, only one village structure was left standing. The disaster claimed the lives of 350 people, with more than 100 bodies never located.

Before-and-after photographs of Nepal’s Langtang Valley showing the near-complete destruction of Langtang village. Photos from 2012 (pre-quake) and 2015 (post-quake) by David Breashears/GlacierWorks. Distributed via NASA Goddard on Flickr.

Since then, scientists have been trying to reconstruct the disaster’s timeline and determine what factors contributed to the village’s tragic demise.

Recently, researchers discovered that the region’s unusually heavy winter snowfall could have amplified the avalanche’s devastation. The research team, made up of scientists from Japan, Nepal, the Netherlands, Canada and the US, published their findings last year in the EGU’s open access journal Natural Hazards and Earth System Sciences.

To reach their conclusions, the team drew from various observational sources. For example, the researchers created three-dimensional models and orthomosaic maps, showing the region both before it was hit by the coseismic events and afterwards. The models and maps were pieced together using data collected before the earthquake and aerial images of the affected area taken by helicopter and drones in the months following the avalanche.

They also interviewed 20 villagers local to the Langtang valley, questioning each person on where he or she was during the earthquake and how much time had passed between the earthquake and the first avalanche event. In addition, the researchers asked the village residents to describe the ice, snow and rock that blanketed Langtang, including details on the colour, wetness, and surface condition of the debris.  

Based on their own visual ice cliff observations by the Langtang river and the villager interviews, the scientists believe that the earthquake-triggered avalanche hit Langtang first, followed then by multiple rockfalls, which were possibly triggered by the earthquake’s aftershocks.

A three-dimensional view of the Langtang mountain and village surveyed in this study. Image: K. Fujita et al.

According to the researchers’ models, the primary avalanche event unleashed 6,810,000 cubic metres of ice and snow onto the village and the surrounding area, a frozen flood about two and a half times greater in volume than the Egyptian Great Pyramid of Giza. The following rockfalls then contributed 840,000 cubic metres of debris.  

The researchers discovered that the avalanche was made up mostly of snow, and furthermore realized that there was an unusually large amount of snow. They estimated that the average snow depth of the avalanche’s mountainous source was about 1.82 metres, which was similar to snow depth found on a neighboring glacier (1.28-1.52 metres).

A deeper analysis of the area’s long-term meteorological data revealed that the winter snowfall preceding the avalanche was an extreme event, likely only to occur once every 100 to 500 years. This uncommonly massive amount of snow accumulated from four major snowfall events in mid-October, mid-December, early January and early March.

From these lines of evidence, the team concluded that the region’s anomalous snowfall may have worsened the earthquake’s destructive impact on the village.

The researchers believe their results could help improve future avalanche dynamics models. According to the study, they also plan to provide the Langtang community with a avalanche hazard map based on their research findings.  

Further reading

Qiu, J. When mountains collapse… Geolog (2016).

Roberts Artal, L. Geosciences Column: An international effort to understand the hazard risk posed by Nepal’s 2015 Gorkha earthquake. Geolog (2016).

Geosciences Column: The science behind snow farming

Geosciences Column: The science behind snow farming

For roughly the last decade, some ski resorts and other winter sport facilities have been using a pretty unusual method to ensure white slopes in winter. It’s called snow farming. The practice involves collecting natural or artificially made snow towards the end of winter, then storing the frozen mass in bulk over the summer under a thick layer of sawdust, woodchips, mulch, or other insulating material.

Many winter sport destinations have adopted the practice. In preparation for the 2014 Winter Olympics, Sochi, Russia stockpiled about 800,000 cubic metres of human-made snow during the warmer season, enough snow to fill 320 Olympic-size swimming pools.

Despite the growing trend, there still is little research on snow farming techniques. Recently, a team of scientists from the Institute for Snow and Avalanche Research (SLF) and the CRYOS Laboratory at the École Polytechnique Fédérale in Switzerland examined the success of snow conservation practices and used models to estimate what factors influence covered snow. Their findings were published in the EGU’s open access journal The Cryosphere.

Why store snow for the winter?

The ski industry has been storing snow for many reasons. The practice is a way for winter sports facilities to accommodate training athletes, start ski seasons earlier, and guarantee snow for major sports events. Snow farming can also be seen as a way to adapt to Earth’s changing climate, according to the authors of the study. Indeed, research published last year in The Cryosphere, found that the Alps may lose as much as 70 percent of snow cover by the end of the century if global warming continues unchecked. Snow loss to this degree could severely threaten the $70 billion dollar (57 billion EUR) industry and the alpine communities that depend on ski tourism.

For some ski resorts, the effects of climate change are already visible. For example, in Davos, Switzerland, a popular venue of the International Ski Federation Cross-Country World Cup, winter temperatures have risen over the last century while snow depth in turn has steadily declined.

Snow heap study

The research team studied two snow heaps: one near Davos, Switzerland (pictured here) and another in South Tyrol. Credit: Grünewald et al.

To better understand snow conservation techniques, the research team studied two artificially made snow heaps: one sitting near Davos and another located in South Tyrol. Each pile contained approximately 7,000 cubic metres of snow, about enough ice and powder to build 13,000 1.8-metre tall snowmen. The piles were also each covered with a 40 cm thick layer of sawdust and chipped wood.

Throughout the 2015 spring and summer season, the researchers measured changes in snow volume and density, as well as recorded the two sites’ meteorological data, including air temperature, humidity, wind speed and wind direction. The research team also fed this data to SNOWPACK, a model that simulates snow pile evolution and helps determine what environmental processes likely impacted the snow.

Cool under heat

From their observations, the researchers found that the sawdust and chipped wood layering conserved more than 75 percent of the Davos snow volume and about two thirds of the snow in South Tyrol. Given the high proportion of remaining snow, the researchers conclude that snow farming appears to be an effective tool for preparing for winter.

According to the SNOWPACK model, while sunlight was the biggest source of snow melt, most of this solar radiation was absorbed by the layer of sawdust and wood chips. The simulations suggest that the snow’s covering layer took in the sun’s heat during the day, then released this energy at night, creating a cooling effect on the snow underneath. Even more, the model found that, when the thick layer was moist, the evaporating water cooled the snow as well. The researchers estimate that only nine percent of the sun’s energy melted the snow heaps. Without the insulating layer, the snow would have melted far more rapidly, receiving 12 times as much energy from the sun if uncovered, according to the study.

Images of the South Tyrol snow heap from (a) 19 May and (b) 28 October. The snow depth (HS) is featured in c & d and snow height change (dHS) is shown in e. Credit: Grünewald et al.

The researchers found that the thickness of the covering layer was an important factor for snow conservation. When the team modelled potential snow melt under a 20 cm thick cover, the insulating and cooling effects from the layer had greatly diminished.

The simulations also revealed that, while higher air temperatures and wind speed increased snow melt, this effect was not very significant, suggesting that subalpine areas could also benefit from snow farming practices.

In the face of changing climates and disappearing snow, snow farming may be one solution for keeping winters white and skiers happy.

References

Grünewald, T., Wolfsperger, F., and Lehning, M.: Snow farming: conserving snow over the summer season, The Cryosphere, 12, 385-400, https://doi.org/10.5194/tc-12-385-2018, 2018.

Marty, C., Schlögl, S., Bavay, M., and Lehning, M.: How much can we save? Impact of different emission scenarios on future snow cover in the Alps, The Cryosphere, 11, 517-529, https://doi.org/10.5194/tc-11-517-2017, 2017.

 

 

GeoSciences Column: When could humans last walk, on land, between Asia & America?

GeoSciences Column: When could humans last walk, on land, between Asia & America?

Though now submerged under 53 m of ocean waters, there once was a land bridge which connected North America with Asia, allowing the passage of species, including early humans, between the two continents. A new study, published in the EGU’s open access journal Climate of the Past, explores when the land bridge was last inundated, cutting off the link between the two landmasses.

The Bering Strait, a narrow passage of water, connects the Arctic Ocean with the Pacific Ocean. Located slightly south of the Arctic Circle, the shallow, navigable, 85 km wide waterway is all that separates the U.S.A and Russia. There is strong evidence to suggest that, not so long ago, it was possible to walk between the two*.

The Paleolithic people of the Americas. Evidence suggests big-animal hunters crossed the Bering Strait from Eurasia into North America over a land and ice bridge (Beringia). Image: The American Indian by Clark Wissler (1917). Distributed via Wikipedia.

In fact, though the subject of a heated, ongoing debate, this route is thought to be one of the ones taken by some of the very first human colonisers of the Americas, some 16, 500 years ago.

Finding out exactly when the Bering Strait last flooded is important, not only because it ends the last period when animals and humans could cross between North America and northeast Asia, but because an open strait affects the two oceans it connects. It plays a role in how waters move around in the Arctic Ocean, as well as how masses of water with different properties (oxygen and/or salt concentrations and temperatures, for example) arrange themselves. The implications are significant: currently, the heat transported to Arctic waters (from the Pacific) via the Bering Strait determines the extend of Arctic sea ice.

As a result, a closed strait has global climatic implications, which adds to the importance of knowing when the strait last flooded.

The new study uses geophysical data which allowed the team of authors to create a 3D image of the Herald Canyon (within the Bering Strait). They combined this map with data acquired from cylindrical sections of sediment drilled from the ocean floor to build a picture of how the environments in the region of the Bering Strait changed towards the end of the last glaciation (at the start of a time known as the Holocene, approximately 11,700 years ago, when the last ‘ice age’ ended).

At depths between 412 and 400 cm in the cores, the sediment experiences changes in physical and chemical properties which, the researchers argue, represent the time when Pacific water began to enter the Arctic Ocean via the Bearing strait. Radiocarbon dating puts the age of this transition at approximately 11, 000 years ago.

Above this transition in the core, the scientist identified high concentrations of biogenic silica (which comes from the skeletons of marine creatures such as diatoms – a type of algae – and sponges); a characteristic signature of Pacific waters. Elevated concentrations of a carbon isotope called delta carbon thirteen (δ 13Corg), are further evidence that marine waters were present at that time, as they indicate larger contributions from phytoplankton.

The sediments below the transition consist of sandy clayey silts, which the team interpret as deposited near to the shore with the input of terrestrial materials. Above the transition, the sediments become olive-grey in colour and are exclusively made up of silt. Combined with the evidence from the chemical data, the team argue, these sediments were deposited in an exclusively marine environment, likely influenced by Pacific waters.

Combining geophysical data with information gathered from sediment cores allowed the researchers to establish when the Bering Strait closed. This image is a 3-D view of the bathymetry of Herald Canyon and the chirp sonar profiles acquired along crossing transects. Locations of the coring sites are shown by black bars. Figure taken from M. Jakobsson et al. 2017.

The timing of the sudden flooding of the Bering Strait and the submergence of the land bridge which connected North America with northeast Asia, coincides with a period of time characterised by Meltwater pulse 1B, when sea levels were rising rapidly as a result of meltwater input to the oceans from the collapse of continental ice sheets at the end of the last glaciation.

The reestablishment of the Pacific-Arctic water connection, say the researchers, would have had a big impact on the circulation of water in the Arctic Ocean, sea ice, ecology and potentially the Earth’s climate during the early Holocene. Know that we are more certain about when the Bering Strait reflooded, scientist can work towards quantifying these impacts in more detail.

By Laura Roberts Artal, EGU Communications Officer

 

*Authors’s note: In fact, during the winter months, when sea ice covers the strait, it is still possible to cross from Russia to the U.S.A (and vice versa) on foot. Eight people have accomplished the feat throughout the 20th Century. Links to some recent attempts can be found at the end of this post.

References and resources:

Jakobsson, M., Pearce, C., Cronin, T. M., Backman, J., Anderson, L. G., Barrientos, N., Björk, G., Coxall, H., de Boer, A., Mayer, L. A., Mörth, C.-M., Nilsson, J., Rattray, J. E., Stranne, C., Semiletov, I., and O’Regan, M.: Post-glacial flooding of the Bering Land Bridge dated to 11 cal ka BP based on new geophysical and sediment records, Clim. Past, 13, 991-1005, https://doi.org/10.5194/cp-13-991-2017, 2017.

Barton, C. M., Clark, G. A., Yesner, D. R., and Pearson, G. A.: The Settlement of the American Continents: A Multidisciplinay Approach to Human Biogeography, The University of Arizona Press, Tuscon, 2004.

Goebel, T., Waters, M. R., and Rourke, D. H.: The Late Pleistocene Dispersal of Modern Humans in the Americas, Science, 319,1497–1502, https://doi.org/10.1126/science.1153569, 2008

Epic explorer crossed frozen sea (BBC): http://news.bbc.co.uk/2/hi/uk_news/england/humber/4872348.stm

Korean team crossed Bering Strait (The Korean Herald): http://www.koreaherald.com/view.php?ud=20120301000341