Week 8: Mass Wasting aka Landslides and Avalanches

This week we're discussing Mass Wasting. Mass Wasting is any downslope movement of earth material. In its more restricted sense, mass wasting refers to any rapid downslope movement of rock or soil. (Keller 210). Most of us know mass wasting by it's common name of landslide or when there is snow involved, avalanche. They range from a single boulder in a rock fall or a large mass of material in a debris flow. They can be triggered by natural events like earthquakes, volcanic eruptions and flooding, but gravity is the driving force. They can also be triggered by human activity such as mining and construction of road or buildings.

Iceland has both landslides and avalanches due to the geological landscape of the country. With it's abundance of volcanoes and glaciers along with winters that produce huge volumes of snow it's only natural that these would be a recurring hazard for the people of Iceland. I couldn't find much detailed information about landslides with regards to Iceland. There are sites that state they do occur frequently but I couldn't find any actual statistics and much of the information is in Icelandic so I was unable to read it. For the most part I found that avalanches, because of the amount of snow they get each winter, are a much bigger concern for Iceland.

Landslides in Iceland:
One recent landslide in Iceland though made the news. In 2014 a landslide in the Askja caldera occurred. Volcanoes are prone to landslides because they are constructed of loose piles of volcanic debris and lava flows on relatively steep slopes.  In this particular landslide the debris flow was so massive that it actually triggered tsunami like waves in the lake of the caldera. Some reports from early information suggest it might be 50-60 million cubic meters of material that moved and the tsunami inside the caldera is estimated to have been 73 meters high. Luckily this caldera is located in a remote part of Iceland and so there were no communities affected by this tsunami. It was though, one of the largest known landslides since the settlement of Iceland.

Askja before

Askja after landslide

Avalanches in Iceland
Avalanches are similar to landslides except that they involve the flow of snow rather than rocks and soil although they have the capability to include ice, rocks, trees, and other material if the avalanche is powerful enough. Avalanches are most common during winter or spring but glacier movements may cause ice and snow avalanches at any time of year. In mountainous terrain, avalanches are among the most serious natural hazard to life and property, with their destructive capability resulting from their potential to carry enormous masses of snow at high speeds (Wikipedia). Snow avalanches and landslides have caused both death and injury and done great damage to infrastructure and property in Iceland. In 1995 two separate avalanches, one in Flateyri and one in Sudavik caused 34 deaths between the two catastrophic events and as a consequence, Iceland's pre-existing snow avalanche and landslide regulations were completely revised. Previously these two villages had been thought safe from an avalanche hazard and so after the avalanches they had to revise their methods of research for avalanche hazard assessment. The Icelandic Meteorological Office is responsible for avalanche warnings and hazard zoning and advices the government on avalanche protective measures. The office employs snow observers in the the most important villages in avalanche-prone areas and maintains a database for avalanches. 

You can get up to date information and danger level of different areas of Iceland from this page: http://en.vedur.is/avalanches/forecast/

They even have this cool avalanche map viewer: http://en.ofanflodakortasja.vedur.is/ofanflod/

One interesting item I came across in my avalanche research had to do with the village of Flateyri. After the devastating avalanche of 1995 they built a special A-shaped earthen dam in 1998 that was built up the mountain to deflect future avalanches. It was put to the test shortly after it was completed and it worked! 

 
In February of 1999, only one year after the dams were completed, a large avalanche from Skollahvilft came crashing down into the eastern side of the dam and the avalanche went into the sea. The next winter, in March, another huge avalanche from the mountain called Innra-Bæjargil slammed into the western and the village was protected again.


Photo credit:
1.Askja landslide: http://en.vedur.is/avalanches/articles/nr/2929 
2.Flateyri protection dam: http://www.amusingplanet.com/2016/01/the-avalanche-protection-wall-of.html
3. Snow covered Flateyri: http://i.imgur.com/U6crt1E.jpg
 

Works cited:

Keller, Edward and Duane DeVecchio. Natural Hazards. New Jersey: Prentice, 2012. Print.

https://en.wikipedia.org/wiki/Avalanche

Thanks for reading!

Jennifer

Week 5: Volcanoes

1.

This week in class we're exploring volcanic activity. Volcanoes are a rupture of the Earth's crust where hot lava, volcanic ash, and gases escape from below the surface. Volcanoes occur here because the Earth's crust is broken into 17 major tectonic plates and most volcanoes can be found where these plates converge or diverge. An example of divergent tectonic plates is the Mid Atlantic Ridge. An example of convergent tectonic plates is the Ring of Fire. My country, Iceland, sits right on top of the Mid Atlantic Ridge, a tectonic plate boundary and a hot spot so volcanoes are a major part of the Icelandic life. 

In fact, if it wasn't for volcanic activity, Iceland would not even exist. Volcanic eruptions in the Mid Atlantic Ridge, on the bottom of the Atlantic Ocean, created a mountain which grew above sea level, and resulted in an island, Iceland. The pocket of magma that sits beneath Iceland is thought to be what created the island, as hot lava rose to the surface of the ocean, where it cooled and gradually accumulated into an island beginning about 70 million years ago. Because of it's location , Iceland has about 130 volcanoes although only 30 are considered active. Iceland has nearly all known types of volcanoes (subaerial, subglacial and submarine) and they are Iceland's biggest and most dangerous natural hazard. Small eruptions happen every 4-5 years in Iceland and given how different each eruption can be they can be either an annoying bother or catastrophic to the inhabitants of Iceland.

2.

Let's take a look at some of the more recent eruptions in Iceland and the hazards they caused: 

When people think of Iceland and volcanoes the one they are most familiar with is the eruption of Eyjafjallajökull back in 2010 that shut European air travel down for six days with it's huge billowing plume of steam and ash. This eruption created the the highest level of air travel disruption since the Second World War and cost the airline industry an estimated loss of $1.7 billion. Eyjafjallajökull is a subglacial volcano located in Southern Iceland. In addition to the interruption of air travel the lava from the eruption also caused ice to melt on the glacier which in turn caused flooding of local steams and rivers, specifically the Markarfljót glacial river which flooded farmland and damaged roads.

Here is a link if you want to learn how to pronounce Eyjafjallajökull:)

Another recent eruption was the Grímsvötn eruption in 2011. This eruption also shut down air travel for 4 days but not to the extent that Eyjafjallajökull did back in 2010. Grímsvötn is Iceland's most active volcano. This eruption was the largest volcanic eruption in Iceland in 50 years. Glacier flooding was expected after this eruption but it never occurred. 

3.
Grímsvötn

Predicting volcanic activity in Iceland:

Volcanic eruptions are among the earth’s most cataclysmic events, and understanding how and when they happen can be crucial to saving lives and reducing damage to infrastructure and other property. Scientists have several powerful tools to help, but in the end, they are often reduced to analyzing possibilities within possibilities, chains of potential events that could unfold in multiple ways. According to our textbook, it is unlikely that we'll be able to accurately forecast the majority of volcanic activity in the near future (Keller 152) The Icelandic Meteorological Office monitors volcanic activity through the South Iceland Lowland national seismic network, various volumetric strain meters and continuous geodetic GPS stations. Despite this monitoring, volcanic eruptions can be different each time and techniques to predict volcanoes are not an exact science. They can only take the seismic activity and other indications of volcanic activity and predict what they "think" will happen. There is no certainty in volcanic activity.


Iceland's emergency guidelines for volcanic activity: 

The Icelandic Department of Civil Protection and Emergency Management developed regional volcanic risk management strategies. Distribution of pamphlets with guidelines for different volcanic zones in Iceland (i.e. ‘Katla-Myrdalsjökull, Hekla, Eyjafjallajökull and Grímsvötn)is one way they are get information to the public. They also put together meetings with tourism companies and mountain hut communities to educate tourists about what to do in case of an eruption. Hazard and emergency response information signs were erected along trails for hikers and tourists. The inhabitants of Iceland are very familiar with volcano precautions but tourists, visiting from so many diverse environments, may not have the education about volcanoes and this could be catastrophic for them. For more information on Iceland’s volcanic hazards and related preparedness measures here are some sites that give safety information:
• http://www.safetravel.is/
• http://en.vedur.is/ 
• http://www.earthice.hi.is/page/ies_volcanoes 
• http://www.vegagerdin.is/english/ road-conditions-and-weather/
 
1.Example pamphlet from the Civil Protection Department regarding the emergency guidelines for the Katla and Eyjafjallajökull volcano eruptions

2. Example poster regarding volcano emergency guidelines for Katla

Works cited:

Keller, Edward and Duane DeVecchio. Natural Hazards. New Jersey: Prentice, 2012. Print.

Photo credit: 
1) Map of volcanoes https://en.wikipedia.org/wiki/Volcanology_of_Iceland
2) Map of volcanoes http://futurevolc.hi.is/volcanoes-and-monitoring
3)  Grímsvötn- http://inapcache.boston.com/universal/site_graphics/blogs/bigpicture/erupticeland_052411/bp4.jpg