Earth Science 208-Volcanic Eruptions
Terms
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- 90% of volcanism is associated with...
- the edges of techtonic plates
- The other 10% of volcanism is situated...
- over hot spots
- 80% of the earth's magma comes out of
- spreading center
- Water lowers the melting point of
- rock
- Economic loss is mostly caused by
- peaceful eruptions
- Why aren't volcanoes right next to the edge of a trench?
- Because the magma has to be able to get hot enough to create a volcano.
- Are basaltic rocks explosive? Why or why not?
- No, because they don't have a high enough level of silica.
- Rising magma partially melts...
- continental crust
- Subduction accounts for what percent of erruptions of all magma?
- 7-13%
- In between the hot spots of volcanoes there are...
- Ridges
- Hot spots are like
- Huge giant like mountains underwater
- What moves the plate or the hot spot?
- The plate moves over the hot spot.
- Does the composition of the oceanic and continental crust react the same or differently?
- Differently because they are composed of different materials.
- Who was Plutonic rock named after and why?
- Pluto, the greek god of the underworld. These rocks are found deep burried in the earth, they cool slowly and create large crystals.
- What magama sticky? Does this stickyness effect the way it errupts?
- Silica makes magma sticky and if magma is sticky it is more likely to errupt.
- Who were the Vulcanion Rocks named after and why?
- Vulcan, the Roman god of fire. These rocks are found close to the surface of the earth, they cool quickly creating large crystals.
- The solubility of volatiles of dissolving gases increases with increasing _________ and decreasing __________.
- Pressure, Temperature
- Viscosity is
- the resistance to flow
- The lower the viscosity the more...
- fluid like it is
- Water has a ________ viscosity.
- Low
- Honey has a ______ viscosity.
- High
- The higher the temperature the __________ the viscosity.
- Lower
- The more silica a rock has the ____________ explosive it is.
- More
- The greater the content of SiO2 the __________ the viscosity.
- Higher
- Viscosity increases the ________ content of magma.
- Mineral
- What percent of the earth's surface is basaltic rock?
- 80%
- As silicate increases, viscosity _____________ and temperature ____________.
- Increases, Decreases
- Why does the vast majority of Earth's magma pour out of spreading centers with ease.
- Because the spreading centers sit above the hight temperature asthenosphere. The rock has a low percentage of SiO2 and the ocean plates pulling apart causes this hot asthenosphere rock to rise and experience lower pressure.
- Why does the magma above subduction zones commonly explode violently?
- When a subducting plate reaches a depth of 60 miles magma is generated and rises, the subducting plate carries sediments and water a hydrated mineral down with it.
- What type of volcanos are more explosive?
- Subduction zone volcanoes
- Magma is generated by what three components?
-
1) Lowering pressure
2) Raising the temperature
3) Increasing the water content - Most magma is generated by what?
- Decreasing the pressure of the hot rock.
- What are three types of lava that come from non-explosive volcanoes?
- Aa, pahoehoe, pillow
- What are types of volcanic materical that come from explosive volcanoes?
- Pyroclastics such as ash, cinders, blocks and bombs and glass such as obsidian and pumice.
- What are the two eruption types of Shield volcanos?
- Icelandic and Hawaiian
- What type of erruption do cinder cones have?
- Strombolian
- What type of erruptions do composite voclanoes have?
- Vulcanian and Plinian
- What were the largest volcanic events on Earth? What did they produce?
- Flood Basalts, produced an immense amount of mass an energy.
- This is the largest of the explosive volcanoes and is formed by the collapse of the roof part of the volcano.
- Caldera
- Examples of a caldera would be...
- Crater Lake in Oregon, Krakataua and Santorini
- An example of an Icelandic shield volcano would be...
- Mauna Loa
- An example of a Hawaiian shield volcano would be...this type of volcano is preceeded by what?
- Haleakala on Maui, preceeded by earthquakes and creates a lava fountain which incinerates buildings and burys highways.
- In Plinian type of eruption how does the volcano errupt?
- The throat of the volcano is cleared by producing an incredible gas powered vertical eruption column.
- In the Vulcanian type of eruption the volcano clears its throat and what follows this?
- A larger erruption.
- Stratovolcanoes or composite cones may what type of eruptions?
- Vulcanian then Plinian then Caldera
- In the Plinian type of eruption what do people suffocate from??
- The gases produced
- What are lahars caused by? What are they good for?
- Lahars are caused when water from the gases fall back to earth as heavy rain and mixes with the ash causing a volcanic mudflow. These lahars are good for agriculture.