Volcanoes Flashcards
Label parts of a volcano diagram
N/A
What are the differences between acidic lava and basic lava?
Acidic lava: Volcanoes at convergent boundaries, High silica content, temperatures of 800°C, high viscosity (pasty) - moves slowly, cools and hardens quickly, gases trapped - violent eruption, forms steep sided volcanoes
Basic lava: Volcanoes at divergent boundaries, low silica content, temperatures of 1200°C, low viscosity (runny) - moves quickly, cools and hardens slowly, gases escape - gentle eruption, forms gently sloping volcanoes
Describe how composite cones are formed and give an example
AKA stratovolcanoes are typically formed at convergent boundaries. Explosive eruptions lead to build up of acidic lava and pyroclastic material in alternating layers creating a steep sided cone. Eg. Mount St Helens USA, Mount Fuji Japan
Draw a diagram of a composite volcano
N/A
What type of eruptions usually occur at composite volcanoes?
Explosive (convergent boundary)
Causes lahars, pyroclastic flows, cinders and ash clouds
What type of magma do composite volacnoes have?
Acidic lava- cooler, thicker, high viscosity, explosive
How much gas do composite volcanoes have?
High levels - pressure builds due to gas trying to escape
Describe how cinder cones are formed and give an example.
Cinder cones are made of pyroclastic material that stuck together after an eruption. They have steep sides and a wide crater at the top. They usually erupt only once as the eruptions destroy their structure. The smallest type of volcano - rarely reach heights above 300m. Usually found around larger volcanoes (shield or composite).
Eg. Paricutin, Mexico
What type of eruptions usually occur at cinder cones?
Mildly explosive
Lava often erupts from sides/base due to weak structure
Gas filled lava cools to become cinders
What type of magma do cinder cones have?
Basic lava - low viscosity, hot, runny
How much gas do cinder cones have?
High levels - expands to form bubbles in lava
What shape are cinder cones?
Small >300m
Steep sides, small crater
Draw a diagram of a lava dome
N/A
Give an example of a lava dome
Mt. St. Helens, USA
What type of eruptions usually occur at lava domes?
Slow
Lava does not flow far
Can be violent
What kind of magma is found at lava domes?
Acidic lava - highly viscous, cools quickly, travels far
How much gas do lava domes have?
Low levels
What shape are lava domes?
Dome shaped
Thick layers of rock
Draw a diagram of a shield volcano
N/A
Give an example of a shield volcano
Mauna Loa, Hawaii
What type of eruptions usually occur at shield volcanoes?
Gentle with lots of magma (divergent boundary)
What kind of magma is usually found at shield volcanoes?
Basic lava - Low viscosity, hot (1200°C), moves quickly
How much gas do shield volcanoes usually have?
Low levels - can escape easily
What shape are shield volcanoes?
Wide and low - gently sloping sides
Describe how calderas are formed and give an example
Formed when composite cones explode violently. When a volcano erupts, it releases a huge amount of magma causing the roof of the now empty magma chamber to collapse in on itself, forming a depression on the earths surface. Over time, calderas can fill with rain or snow eg. Caldera from Mount Pinatubo eruption 1991 now filled with rainwater.
Describe how shield volcanoes are formed and give an example
Usually form at divergent boundaries or hotspots. They are formed from gentle eruptions of basic lava that then spread over a wide area. These layers build up to form a gently sloping volcanic mountain. Largest volcano type on earth - often more than 100km in diameter.
Eg. Mauna Loa, Hawaii
What is a volcano?
A volcano is an opening in the Earth’s surface that allows molten rock, ash, and gases to escape from bellow the crust. When pressure builds up in the Earth’s mantle, it causes eruptions, forming mountains or craters.
Define magma
Molten rock beneath the Earth’s surface
Define lava
Molten rock that has erupted onto the Earth’s surface
Define crater
A bowl shaped depression at the top of a volcano
Define vent
The opening through which volcanic material is emitted
Define ash
Tiny fragments of rock and minerals emitted during an eruption
What is Mount Vesuvius known for?
The eruption that destroyed Pompeii in AD 79
Where is Krakatoa located
Indonesia
What is Krakatoa known for?
Its 1883 eruption was one of the deadliest in recorded history.
What is Mount St. Helens known for?
Erupted explosively in 1980, causing widespread damage.
Name and explain the two different types of volcanic eruptions
Explosive eruptions: Violent eruptions that release ash, gas, and pyroclastic flows
Effusive eruptions: Lava flows smoothly and quietly out of a volcano
Where are the three different places volcanoes can be found at?
Divergent boundaries, convergent boundaries and hotspots
What are volcanologists?
Scientists who study volcanic activity
Name and explain five ways that volcanologists can predict volcanic activity.
- Ground deformation monitoring:
Scientists use GPS (Global Positioning System) and tiltmeters to measure changes in the shape of the volcano. Swelling or deformation of the ground may indicate movement of magma. - Seismic monitoring:
Seismometers are used to detect and record volcanic earthquakes. Monitoring the frequency, intensity and depth of the seismic activity provides insights into volcanic behaviour. - Gas Emission Monitoring:
Volcanoes release various gases, including sulphur dioxide, carbon dioxide and water vapour, from magma beneath the surface. Ground based and satellite based instruments are used to measure gas concentrations and track variations. - Volcano geology and history:
Studying geological history of a volcano and its eruption patterns provide valuable information. Studying volcanic deposits can show the frequency, size, and types of eruptions a volcano is capable of. - Remote sensing technology:
Satellites equipped with various sensors, such as thermal imagery and gas detectors allow scientists to monitor volcanic activity from a distance.
Name and give examples of three positive effects of volcanoes
TOURISM:
Blue Lagoon:
Geothermal spa in lava field near Reykjavik, attracts over 1.3m visitors annually.
One of Icelands most popular tourist attractions, contributing to country’s economy by combing geothermal activity with wellness tourism.
Mount Fuji:
3,777m high. UNESCO worl heritage site. Attracts around 300,00 climbers each year during the official climbing season.
Millions more come for sightseeing, photography and cultural experiences around volcano contributing billions to tourism sector
Mount Etna:
Draws <1m tourists annually.
Volcanoes are key to Sicily’s tourism, boosting local economy, businesses, restaurants and tour operations.
CREATION OF NEW LAND/FERTILE SOIL:
New land:
New land formed from build up of volcanic material
Iceland is the youngest country on earth, having formed 16-18m years ago as layers of basalt built up at Mid Atlantic Ridge
Iceland is getting bigger as North American and Eurasian Plates separate.
Fertile soil:
Soils formed from the breakdown oc volcanic deposits are the most fertile soil in the world. Suitable for intensive agriculture.
Land around slops of Mount Vesuvius is cultivated to grow veg, fruit, and flowers.
Volcanic soils are vital to survival of 1m people living within 30km of Mount Merapai, Java, Indonesia as majority of island’s rice is grown there.
GEOTHERMAL ENERGY:
Underground reservoirs of super heated water due to volcanoes are drilled into and the water is pumped out. As it reaches the surface it turns to steam. This is then funneled through turbines to generate power.
Iceland has 130 volcanoes and 600 hot springs. Geothermal energy makes up 30% of its energy.
After generating electricity, the steam is used to heat homes and businesses by heating water from another lake and piping it there. It is also used to heat greenhouses, helping Iceland become self sufficient.
Geothermally heated water is used to heat fish farms for salmon and trout.
Led to formation of Blue Lagoon in 1976 which 1.3m people visit annually. Many believe bathing in it has health benefits.
By 2030, the Iceland Deep Drilling Project aim to double Iceland’s geothermal energy production. Iceland is planning to sell geothermal energy to other countries eg. The UK using ‘Ice-Link’, the world’s largest interconnector.
Name and give examples of four negative effects of volcanoes
LAHARS
A lahar is a destructive mudflow composed of ash, debris and water. that occur when a volcano has ice/glaciers on top of it.They can bury and destroy infrastructure, agriculture and communities.
Examples:
Nevado Del Ruiz, Columbia, 1985 - The eruption triggered lahars that destroyed the town of Armero. ~23,000 people killed. ~5,000 homes destroyed.
Mount Pinatubo, Philippines, 1991 - Lahars were triggered by heavy rainfall after the eruption, burying villages. Over 100,00 homes destroyed and 320 people killed by lahars.
NUEE ARDENTE (PYROCLASTIC FLOW)
A nuee ardente is a fast moving, extremely hot cloud of gas, ash and volcanic debris. It is one of the deadliest volcanic hazards due to its speed and temperature.
Example:
Mount Pelee, Martinique, 1902 - A pyroclastic flow destroyed the town of St Pierre and 29,000 people killed in minutes.
FLIGHT INTERRUPTION:
Volcanic ash can be dangerous for aircraft, as ash particles can damage engines and reduce visibility, causing large-scale flight disruptions.
Example:
Eyjafjallajökull, Iceland (2010) - The ash cloud from this eruption led to widespead flight cancellations across Europe. Over 100,00 flights cancelled and cost airlines and businesses ~1.7b US dollars
LOSS OF LIFE:
Volcanic eruptions can lead to significant loss of life due to pyroclastic flows, lahars, falling ash and other hazards.
Example:
Mount Vesuvius, Italy (79 AD) - The eruption buried the cities of Pompeii and Herculaneum under volcanic ash and pumice. 13,000-16,000 people died.
How many active volcanoes are there in the world?
1500
How many people in the world live within 100km of an active volcano?
~800m people, 10% of the population
Explain how the study of plate tectonics has helped to understand the global distribution of volcanoes
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Draw and label diagram of intrusive and extrusive volcanic landforms
N/A
Discuss the positive impacts of volcanic activity (30m)
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