Unit 3- The Restless Earth: Volcanoes Flashcards
What is ejected from a volcano?
Molten lava erupts through the vent and solidifies as igneous rock. Gas, dust, volcanic bombs and other materials can also be ejected.
What are the characteristics of composite volcanoes?
- Eruptions are infrequent but often violent.
- Steep sided and are made of a variety of materials; e.g. lava and ash
What is a volcano and how can they be labelled?
A volcano is and opening or vent in the Earth’s surfaces do can be labelled as dormant, active or extinct.
What are the characteristics of a shield volcano?
- Broad based and gentle slopes.
- Layers of runny ash and lava.
- Eruptions are frequent but non-violent.
Describe the case study of The Nyiragongo Volcano. (Excluding effects)
- 17th January 2002 along the East African Rift Valley.
- There were fissure eruptions, three of which had lava travelling up to 60km/hour.
What were the primary social effects?
- 45 people died within the first 24 hours.
- 14 villages were destroyed.
- Homes and roads were destroyed by lava.
- The Goma airport runway was damaged.
What were the secondary social effects?
- Half a million people escaped to Rwanda.
- Many people slept on the streets of Gisenyi.
- There were outbreaks of cholera.
- It was difficult to travel around Goma.
What were the primary economic effects?
- Fuel stores and nuclear power stations exploded.
- By one month, 350,000 people were dependant on aid from Oxfam and Christian aid.
- Valuables were lost or destroyed.
- Jobs and businesses were lost.
What were the primary environmental effects?
-lava destroyed the cities wildlife and agriculture.
What were the secondary environmental effects?
- Methane and CO2 could be released from the bottom of Lake Kivu if disturbed by volcanic or seismic activity.
- Wildlife can be killed from volcanic gases.
Describe the eruption of Eyjafjallajokull, Iceland. (Exclude effects).
- Occurred on 14th April 2010.
- When American and Eurasian plate moved apart and magma raised and solidified, forming a series of active volcanoes.
- The volcano is in Northern Iceland, 125km away from the capital.
What were the local effects of the Eyjafjallajokull volcano?
- Crops were damaged due to lava and ash.
- Due to flooding, defences were damaged.
- Local water supplies were contaminated with Fluoride.
- 800 people near the volcano had to be evacuated.
- Services such as electricity and water were damaged.
What were the national impacts of the Eyjafjallajokull eruption?
- Road transport was affected.
- Tourism declined affecting jobs and the economy.
- Reconstruction of damaged buildings, defences and roads was expensive.
- Agriculture was affected.
What were the international effects of the Eyjafjnallajokull eruption?
- Within 8 days, 100,000 flights were cancelled = 48% of total air traffic. This affected 10 million passengers and costed £80 million.
- Industries(e.g. Honda) had a temporary halt as they could not get raw materials
- Sporting events were affected such as the French rugby league and Boston Marathon.
What were the positive impacts of Eyjafjnallajokull eruption?
- It is a tourist attraction.
- Volcanic rocks can be used for building materials.
- Soils became very fertile.
- Minerals such as Silver, Gold and Copper can be mined from volcanic regions.
- Sulphur can be deposited for bleaching sugar, making matches and making fertilisers.
- Geothermal energy can be used for electricity.
What are the signs of volcanic/seismic activity?
- Animal behaviour
- Geothermal energy
- Water temperatures in ponds rising.
- TiltMeters
- Swelling of volcanoes.
- Increase in gas emissions.
What preparations can be made for volcanoes or earthquakes?
- train emergency services
- practice drills
- have an emergency supply of basic provisions.
- ensure that money is available to deal with the problems.
- Build earthquake proof buildings.
What are Lahars?
Mudflows resulting in melting ice or water mixing with ash.
What are hazard maps?
Maps that show areas that are of risk to natural hazards.
What is a supervolcano?
A mega colossal volcano that erupts nearly 1,000km^3 of material.
Describe the Yellowstone volcano.
The Yellowstone supervolcano was formed due to a volcanic hotspot and every year, millions of visitors come to see the geothermal features of geysers and hot springs. Within the last 3 million years, the volcano has erupted 3 times and the last eeuption was 650,000 years ago. It was 1,000 times larger than the Mount St.Helen’s eruption in 1980 and created a caldera 55 by 80 km wide.
What would happen if the Yellowstone volcano erupted?
There would be catastrophic effects worldwide and would most likely:
- destroy 10,000km^2 of land
- kill 87,000 people
- Buildings within 1,000km would be covered by 15cm of ash.
- 1 in 3 people affected would die.
- The Uk would be affected 5 days later and global climates would change along with crops failing.
What is a caldera?
Huge depressions created in supervolcanos when the magma chamber collapses.
What is a geyser?
A geothermal feature where water erupts into the air under pressure.
What is a hotspot?
Sections of the earth’s crust where plumes of magma rise and weaken the crust. They are usually away from plate boundaries.
