AQA GCE Geography Unit 3- 7th June 2013

Hello the types of volcanoes are linked to the types of lava and plate margins. For example, at a constructive plate boundary, shield volcanoes are common such as Surtsey in Iceland because basaltic lava is common at this boundary. This lava is runny and less explosive so the lava spreads out more, hence why the volcano has gently sloping slides because the lava doesn't build up as much.
This is opposite to destructive plate boundaries which have andesitic and rhyolitic lava. This lava is more explosive and more viscous so builds up more, forming composite volcanoes with steep sides and layers of ash, such as Mt St Helen's before it erupted to form a caldera volcano.

As for the frequency, I'm not too sure what its asking for, but maybe just simply whether its an active or dormant volcano. if its active then people are likely to be more prepared for an eruption.

Hope this helps x


Posted from TSR Mobile

What extrusive volcanic landforms do we need to know? (types of volcanoes) My teacher taught us Icelandic, Hawaiian, Vesuvian, Krakatoan, Pelean and Pinean but there appears to be no mention of these in the text book, which has - dome, caldera, shield and fissure. Theres so much to learn on the syllabus, I don't really want to learn extra! any one stressing yet?!

What extrusive volcanic landforms do we need to know? (types of volcanoes) My teacher taught us Icelandic, Hawaiian, Vesuvian, Krakatoan, Pelean and Pinean but there appears to be no mention of these in the text book, which has - dome, caldera, shield and fissure. Theres so much to learn on the syllabus, I don't really want to learn extra! any one stressing yet?!

Hawaiian - This type of activity is the like of Mauno Loa and Kilauea Volcanoes. Hawaiian eruptions are the calmest types of volcanic events, characterized by the effusive eruption of very fluid basalt-type lavas with low gaseous content. Eruptions are not centralized at the main summit as with other volcanic types, and often occur at vents around the summit. Mount Etna is also known to have Hawaiian activity.

Strombolian- This type of volcanic activity is named after the volcano Stromboli, which has been erupting continuously for centuries. Strombolian eruptions are driven by the bursting of gas bubbles within the magma. These gas bubbles within the magma accumulate and coalesce into large bubbles, called gas slugs. These grow large enough to rise through the lava column. Upon reaching the surface, the difference in air pressure causes the bubble to burst with a loud pop, throwing magma in the air in a way similar to a soap bubble. Because of the high gas pressures associated with the lavas, continued activity is generally in the form of episodic explosive eruptions accompanied by the distinctive loud blasts. During eruptions, these blasts occur as often as every few minutes.

Vulcanian - In Vulcanian eruptions, highly viscous magma within the volcano make it difficult for vesiculate gases to escape. Similar to Strombolian eruptions, this leads to the buildup of high gas pressure, eventually popping the cap holding the magma down and resulting in an explosive eruption. However, unlike Strombolian eruptions, ejected lava fragments are no aero dynamical. They are also more explosive than their Strombolian counterparts, with eruptive columns often reaching between 5 and 10km high. Lastly Vulcanian deposits are andesitic rather than basaltic. Example includes Sakurajima, Japan.

Pelean - Is a type of volcanic eruption, named after the volcano Mount Pelee. In Pelean eruptions, a large amount of gas, dust, ash and lava fragments are blown out in the volcano's central crater, and that often creates large eruptive columns. An early sign of a coming eruption is the growth of a lava spine, a bulge in the summit preempting to its total collapse. The material collapses upon itself, forming a fast-moving pyroclastic flow. These massive landslides make Pelean eruptions one of the most dangerous in the world. Volcanoes known to have Pelean activity are Mount Pelee and Mayon Volcano in the Phillippines.

Plinian - High explosive eruptions that occur mostly at stratovolcanoes. Eruptions can last anywhere from hours to days. Plinian eruptions are similar to both Vulcanian and Strombolian eruptions, except that rather than creating discrete explosive events, Plinian eruptions form sustained eruptive columns, which can reach up to 45km in height. The most dangerous feature are pyroclastic flows generated by material collapse, which move down the side of the mountain at up to 435m/ph. The ejection of hot material from the volcano's summit melts snow banks and ice deposits on the volcano, which mixes the tephra to form lahars, fast moving mudslides with the consistency of wet concrete that move at the speed of a river rapid. Major Plinian eruptive events include Mount Vesuvius in AD 79. The 1980 eruption of Mount St. Helens was a Plinian eruption.

Surtseyan - A type of volcanic eruption caused by shallow-water interactions between water and lava, named so after its most famous example, the eruption and formation of the island of Surtsey off the coast of Iceland. Surtseyan eruptions are the "wet" equivalent of ground-based Strombolian eruptions, but because of where they are taking place they are much more explosive.

Fissure eruptions - occur where an elongated crack in the crust allows lava to spill out over a large area. Typically tthese are found around spreading ridges where tension pulls the crust apart - for example, the eruption at Heimaey, Iceland in 1973. When the Eurasian and North American Plates pulled apart, existing topography was drowned in a vast lake of basaltic lava. Fissure eruptions are characterized by a curtain of fire, a curtain of lava spewing out to a small height above the ground.

Shield Volcanoes - are made of basaltic rock and form gently sloping cones from layers of less viscous lava. These volcanoes are known for producing the Hawaiian Islands and are some of the largest in the world, both in height and width. Shield volcanoes are squatty, being lower to the ground, yet having a huge base.

Composite / Stratovolcano - The most common type found on land. They are created by layers of ash from initial explosive phases of eruptions and subsequent layers of lava from the main eruption phases. They are characterized by a fairly symmetrical mountain edifice. They tend to have highly infrequent eruptions ----------------hundreds of years apart-- and typically form at subduction zones.

Ciner Cone Volcanoes - These are steep-sided volcanoes formed from very viscous lava. As the lava cnnot travel far, it builds up convex cone-shaped volcanoes. Lava may solidify in the vent and be revealed later by erosion. They usually remain compartively small and are active only for a short time.

Calderas - Form when gasees that have built up beneath a blocked volcanic event result in a catstrophic eruption that destroys the volcano summit, leaving an enormous crater where later eruptions may form smaller cones. In the case of Crater Lake in the US, the caldera has filled with water, while in the case of Krakatoa in Indonesia and Thera/Santorini in Greece, the sea has inundated the broken remains of the volcano.

Anyone doing Weather and Climate?

Do we really need to know all this?! Argh! Hawaiian - This type of activity is the like of Mauno Loa and Kilauea Volcanoes. Hawaiian eruptions are the calmest types of volcanic events, characterized by the effusive eruption of very fluid basalt-type lavas with low gaseous content. Eruptions are not centralized at the main summit as with other volcanic types, and often occur at vents around the summit. Mount Etna is also known to have Hawaiian activity.

Strombolian- This type of volcanic activity is named after the volcano Stromboli, which has been erupting continuously for centuries. Strombolian eruptions are driven by the bursting of gas bubbles within the magma. These gas bubbles within the magma accumulate and coalesce into large bubbles, called gas slugs. These grow large enough to rise through the lava column. Upon reaching the surface, the difference in air pressure causes the bubble to burst with a loud pop, throwing magma in the air in a way similar to a soap bubble. Because of the high gas pressures associated with the lavas, continued activity is generally in the form of episodic explosive eruptions accompanied by the distinctive loud blasts. During eruptions, these blasts occur as often as every few minutes.

Vulcanian - In Vulcanian eruptions, highly viscous magma within the volcano make it difficult for vesiculate gases to escape. Similar to Strombolian eruptions, this leads to the buildup of high gas pressure, eventually popping the cap holding the magma down and resulting in an explosive eruption. However, unlike Strombolian eruptions, ejected lava fragments are no aero dynamical. They are also more explosive than their Strombolian counterparts, with eruptive columns often reaching between 5 and 10km high. Lastly Vulcanian deposits are andesitic rather than basaltic. Example includes Sakurajima, Japan.

Pelean - Is a type of volcanic eruption, named after the volcano Mount Pelee. In Pelean eruptions, a large amount of gas, dust, ash and lava fragments are blown out in the volcano's central crater, and that often creates large eruptive columns. An early sign of a coming eruption is the growth of a lava spine, a bulge in the summit preempting to its total collapse. The material collapses upon itself, forming a fast-moving pyroclastic flow. These massive landslides make Pelean eruptions one of the most dangerous in the world. Volcanoes known to have Pelean activity are Mount Pelee and Mayon Volcano in the Phillippines.

Plinian - High explosive eruptions that occur mostly at stratovolcanoes. Eruptions can last anywhere from hours to days. Plinian eruptions are similar to both Vulcanian and Strombolian eruptions, except that rather than creating discrete explosive events, Plinian eruptions form sustained eruptive columns, which can reach up to 45km in height. The most dangerous feature are pyroclastic flows generated by material collapse, which move down the side of the mountain at up to 435m/ph. The ejection of hot material from the volcano's summit melts snow banks and ice deposits on the volcano, which mixes the tephra to form lahars, fast moving mudslides with the consistency of wet concrete that move at the speed of a river rapid. Major Plinian eruptive events include Mount Vesuvius in AD 79. The 1980 eruption of Mount St. Helens was a Plinian eruption.

Surtseyan - A type of volcanic eruption caused by shallow-water interactions between water and lava, named so after its most famous example, the eruption and formation of the island of Surtsey off the coast of Iceland. Surtseyan eruptions are the "wet" equivalent of ground-based Strombolian eruptions, but because of where they are taking place they are much more explosive.

No you don't need to learn it in this level of detail, I would suggest just learn the type if eruption for the case studies you are studying- that is more than enough!

Dont forget the minor extrusive like geysers, hot springs and boiling mud pools. I've learnt the different types such as caldera and fissure. And yes I am stressing!!

Posted from TSR Mobile

Icelandic, Hawaiian, Vesuvian, Krakatoan, Pelean and Pinean are used to describe the TYPE OF ERUPTION.



Where-as dome, caldera, fissure are all described the TYPE OF VOLCANO.



But some volcanoes obviously won't produce different types of eruption to their shape. Personally I would know both, dome, cinder cone and all of those aren't really that hard. They are formed differently to the make-up of the lava essentially.

Ecosystems: what are everyones case studies for fragile environments? Are they tropical biomes or the Gulf of Mexico stuff? Or both?
quite confused as to what a fragile environment is!

I'm fine with the minor extrusive and really like the intrusive! I'll do that then. Me too, nothing seems to be going in!

I'm learning Serengeti, the Amazon and the Arctic! There's loads of stuff on the Internet/ in textbooks etc


Posted from TSR Mobile

Am I the only one finding it really difficult to learn the sheer amount of info there is ?

really struggling

Im stuck on the whole tri-cecular model can anyone explain?