Week 5 Blog: Volcanoes

A volcano is a vent or chimney which transfers molten rock known as magma from depth to the Earth's surface. Magma erupting from a volcano is called lava and is the material which builds up the cone surrounding the vent.

A volcano is active if it is erupting lava, releasing gas or generates seismic activity. A volcano is dormant if it has not erupted for a long time but could erupt again in the future. Once a volcano has been dormant for more than 10 000 years, it is termed extinct.

The explosiveness of a volcanic eruption depends on how easily magma can flow and the amount of gas trapped within the magma. Large amounts of water and carbon dioxide are dissolved in magma causing it to behave in a similar way to gas expanding in fizzy drinks, which forms bubbles and escapes after opening.

Volcanoes can be different in appearance with some featuring perfect cone shapes while others are deep depressions filled with water. The form of a volcano provides a clue to the type and size of its eruption which is controlled by the characteristics and composition of magma. The size, style and frequency of eruptions can differ greatly but all these elements correlated to the shape of a volcano.

Are there volcanoes in Finland? The answer is no, but Finland does have ancient volcanoes that are 2,500 Millions years old. The thought is that Finland's bedrock is so stable form the collision of volcanic island arcs. The oldest volcanic rocks is found in Finland and are called the Archean Greenstone Belts. The green area on the map below shows the oldest volcanic rock from the ancient volcanoes.

Finland is not in any danger from active volcanoes in the country, but has had to deal with the after math from other volcanic eruptions in other countries.  For example, the volcanic eruption from Holuraun volcano in Iceland, brought unusually high concentrations of volcanic gases to the people in Finland. The gases affected their quality of life and were instructed to stay indoors. 

Interesting tidbit: Volcanic ash clouds can damage aircraft engines but ash is not visible by radar, the main navigation aid for aircraft. There are nine Volcanic Ash Advisory Centres around the world which use satellites to help track volcanic ash clouds and provide warnings for aircraft.

Refrences:

http://www.ga.gov.au/scientific-topics/hazards/volcano/basics/what

www.luomus.fi/en/ancient-volcanoes-finland

http://www.wsj.com/articles/iceland-volcanic-eruption-sending-gases-throughout-region-1410446383