Some are extinct, but over 30 are still active. The island is covered with more than 100 volcanoes. As the plates pull apart, molten rock (magma) rises up and erupts as lava, creating new ocean crust. Iceland lies on the Mid Atlantic Ridge, a constructive plate boundary, where the North American and Eurasian plates are moving away from each other. Volcanoes can sometimes form in these setting one example is Iceland. The Earth’s crust is pulled apart to create a new pathway for rising hot magma to flow on to the surface. Read more Constructive plate boundary volcanoesĪt constructive plate boundaries, the tectonic plates are moving away from one another. It erupts from vents, sometimes as lava, but usually the magma becomes solid within the volcanic vent, giving much more explosive eruptions.Īuthor Chris King, reproduced with the author’s permission from Exploring Geoscience Across The Globe. The eruption of intermediate and silicon-rich magma is very different. Rivers of lava can flow over the ground or move more slowly as blocky masses bulldozing along. When runny basaltic magma erupts as lava, it pours out of the ground along long surface cracks or through volcanic vents and may be sprayed into the air as spectacular lava fountains. So in summary, iron/magnesium-rich basaltic magmas are free-flowing with low viscosity, while intermediate and silicon-rich magmas are very sticky with high viscosity. When magmas contain a lot of gas this makes them more runny too, although basaltic magmas usually do not contain much gas. Basaltic magmas also tend to contain few crystals, increasing their runniness.
Basaltic magmas are also usually the hottest and the hotter the magma is the less viscous it is as well. The balance between iron/magnesium and silicon composition changes the runniness: iron/magnesium-rich basaltic magmas are the most runny (low viscosity) at one end of the scale and silicon-rich are the least runny (highly viscous) at the other end. What are we doing about climate change?.Understanding carbon capture and storage.What causes the Earth’s climate to change?.NGR hydrocarbons (well samples) database.Palaeontology and biostratigraphy collections.Donations and loans of materials collections.Engineering and Geotechnical Capability.Integrated resource management in Eastern Africa.Rock Volume Characterisation Laboratory Cluster.Fluid and Rock Processes Laboratory Cluster.Equality, diversity and inclusion at BGS.Environmental policy and sustainability strategy.Lava loop.wav by Audionautics is licensed under CC-BY-3.0. Kīlauea Volcano - Fissure 8 Lava Fountain by USGS is in the public domain. Kīlauea Volcano - USA Overlight of Lower East Rift Zone by USGS is in the public domain.Įrta Ale Volcano, Ethiopia by Ifan Chang is licensed under CC-BY-3.0. Plate Tectonics, Paleogeography, and Ice Ages is licensed under CC-BY-3.0. Welcome to Lava Block by Lava Block is licensed under CC BY-SA 3.0. Volcano Eruption Sound by SPANAC is licensed under CC BY 4.0. Thingvellir ( Þingvellir ) National Park in western Iceland from drone Phantom 4 by World&Drone is licensed under CC BY 3.0. NASA Scientist Reveals Greenland's Geologic Past by NASA is in the public domain. Plate Boundaries (white) by Science On a Sphere is in the public domain. Videography by: Vratislav Karas, Rob Parker, Harriet Ridley.
Written and developed by: Rich Waller, Rhian Meara, Rob Parker, Harriet Ridley, Tony Escritt, Tim Parker. In this video, we team up with Dr Rich Waller to explore how energy from deep within the Earth drives the plates apart at divergent-or constructive-plate boundaries to create new oceanic crust. The Time for Geography team is in southwest Iceland to explore the boundary between two of the Earth's largest tectonic plates!
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