Volcanic Hazards Flashcards
Where is Mount Merapi located?
On Java, Indonesia, part of the Pacific Ring of Fire.
What happened during the 2010 Mount Merapi eruption? (Mention 3 things)
• VEI 4 eruption in October-November 2010.
• Pyroclastic flows reached 15km from the crater.
• 350,000 people evacuated and 353 killed.
What were the 3 social and economic impacts of the Mount Merapi eruption?
• Homes, schools, and farmland destroyed.
• $600 million in economic losses.
• Ash fall affected Yogyakarta and nearby cities.
What were the 3 short-term responses to the Mount Merapi eruption?
• Evacuation of 350,000 people.
• Emergency aid and shelters were provided.
• Airports closed due to ash clouds.
What were the 3 long-term responses to the Mount Merapi eruption?
• New hazard maps created to mark exclusion zones.
• Improved monitoring systems installed.
• Rebuilding of homes and infrastructure.
What is lava?
magma (molten rock) above the surface.
Can you give 3 facts about lava?
- Lava flows can move as fast as 10 km/h and bury or set alight things in their path.
- The speed of a lava flow depends on the materials making up the lava - basalt flows are runnier and move faster, whereas andesite flows are thicker (more viscous) and move slower.
- Thick lava flows are at risk of collapsing, which can cause pyroclastic flows.
What do volcanic gases contain? (Give 2 things)
Carbon dioxide and sulphur dioxide
What is pyroclastic fallout?
any material that has been ejected from a volcano and has travelled through the air or atmosphere and fallen to earth.
What is ash?
Tiny pieces of burnt rock fragments that are blown into the atmosphere, usually at some force.
What are pryoclastic flows/nuées ardentes and give 3 facts?
Currents of hot ash, lava and gas that can move downhill at speeds of up to 500km/h during an eruption.
-They can reach temperatures of up to 1000°C and can cover distances of up to 30km from the volcano.
What is tephra?
rock fragments that are ejected from the eruption and can travel as far as 80km away from the site of the eruption.
What are Lahars?
Fast-moving flows of volcanic material and water.
What are the 4 ways of predicting volcanic eruptions?
1) gas emissions
2) seismic waves
3) volcanic swelling
4) thermal images
How do gas emissions predict volcanic eruptions?
As magma reaches the surface, dissolved gases are released into the atmosphere. Therefore, Gas emissions can be detected and monitored for changes.
How do seismic waves predict volcanic eruptions?
Seismic waves can be monitored to see changes in activity. Increased seismic waves are a sign a volcano could be about to erupt. Earthquakes are a sign of a nearby volcanic eruption.
How do volcanic swelling predict volcanic eruptions?
- A volcano may swell up before an eruption as gases and magma build up close to the surface of the volcano.
- Scientists can measure the rate of swelling and the angle the volcano is swelling at.
- Tiltometers can be used to measure this swelling.
How do thermal images predict volcanic eruptions?
- Changes in the magma and movement closer to the surface of a volcano can be monitored by using thermal images.
- Other indicators of volcanoes, such as changes in geysers and hot springs, can be seen using thermal images.
