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Description
Flashcards by Faiza Pathan, updated more than 1 year ago
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Created by Faiza Pathan
over 7 years ago
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| Question | Answer |
| Facts about volcanoes | 1: Formed by eruptions of lava + ash 2: Usually cone shaped mountain/hills 3: Magma becomes lava when it reaches Earth's surface 4: Happen at constructive + destructive boundaries 5: Can happen underwater ie. seabed/ocean floor |
| How do volcanoes form? | 1: Magma rises through weaknesses (cracks) in the Earths crust 2: Pressure build up inside the Earth 3: Pressure is released - ( Due to plate movement, magma explodes to the surface) 4: Volcanic eruption 5; Lava erupted cools and forms new crust * Over time, after lots of eruptions, rock builds up and a volcano forms. |
| How does magma push up between the 2 plates? | |
| Describe: A) Magma chamber B) Crater C) Main vent D) Secondary vent | A) Created after an eruption blows the top off the volcano B) Collection of magma beneath the Earth C) Main outlet for magma escape D) Smaller outlet for magma escape |
| How does an eruption occur? | 1: Pressure in magma chamber forces magma up the main vent 2: Magma heads for the crater at the top of the volcano * Some magma may be force out of the secondary vent (side of volcano) |
| Volcanic activity | 1: Active - Erupts frequently 2: Dormant - Temporarily inactive ; not fully extinct 3: Extinct - Unlikely to re-erupt |
| Shield volcanoes | 1: Found at Constructive/Tensional boundaries 2: Low - Have gently sloping sides 3: Formed by eruptions of thin runny lava 4: Frequent eruptions ( Gentle ) |
| Shield volcano structure | |
| Composite volcanoes | 1: Made up of alternating layers of Lava + Ash 2: Found at destructive/compressional boundaries 3: Eruption has a pyroclastic flow ( Not lava flow ) * Pyroclastic flow - 1: Mixture of hot steam, ash, rock + dust 2: High in speed when rolling down side of volcano 3: Temperature 400°C + |
| Composite volcano structure | |
| Pyroclastic flow | 1: Mixture of hot steam, ash, rock + dust 2: High in speed when rolling down side of volcano 3: Temperature 400°C + |
| Super Volcanoes ( Volcano on a massive scale ) | * Different from a volcano: 1: Erupts minimum 1,000 km3 of material (a large volcano erupts around 1 km3) 2: Form Caldera ( A volcano forms a cone shape) 3: Has a ridge of highland around it 4: Erupts less - Eruptions 100's of 1000's years apart |
| Effects of a volcanic eruption POSITIVE | 1: Creates dramatic scenery - Attracts Tourists 2: Fertile soil created by deposition of lava + ash - Good for agriculture 3: Opportunities of Geothermal energy |
| Effects of a volcanic eruption NEGATIVE | 1: Many deaths 2: Risk of Lahars - If ash + mud from an eruption mix with rain or snow, speedy mudflows are created 3: Settlements can be destroyed 4: Clear areas of woodland + agriculture 5: Human/Natural landscapes can be lost |
| Predicting volcanic eruptions WARNINGS | 1: 100's of minor earthquakes caused 2: Temperature increases around volcano 3: Gases begin to be released (Happens when volcanoes are close to erupt) * Higher sulfur content of gas = volcano is close to erupt |
| Predicting volcanic eruptions MONITORING TECHNIQUES | 1: Seisometers used to detect Earthquakes 2: Thermal imaging + Satellite cameras detect heat around volcano 3: Gas samples may be taken + chemical sensors - measure sulfur levels |
| Preparing for volcanic eruptions | 1: Create exclusion zone around the volcano 2: Being ready for evacuation of residents 3: Having emergeny supply of basics 4: Keep emergency fund - For emergency 5: Having a good communication system |
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