Transcript Chapter 5 Section 2: Volcanic Eruptions
Chapter 5 Section 2: Volcanic Eruptions
Directions : Define the following terms.
1. Magma chamber 2. pipe 3. vent 4. Lava flow 5. crater 1. Magma collects in a pocket beneath a volcano 2. A long tube through which magma moves from the chamber to the surface.
3. An opening through which molten rock and gas leave a volcano.
4. The area covered by lava as it pours out of a volcano’s vent 5. A bowl shaped area that forms around a volcano’s central opening.
6. Label the picture: lava flow, vent, crater, magma chamber, pipe
• • • 7. What are the two types of volcanic eruptions?
Quiet Explosive • • 8. What is silica?
Material found in magma • 9. A volcano erupts quietly if its magma is __________ or _________________.
Directions: Which does the following describe? Pahoehoe or aa
10. Looks like a solid mass of ropelike coils 10. Pahoehoe 11. Rough surface of jagged lava chunks 11. Aa 12. Forms from fast moving, hot lava that is thin and runny 12. Pahoehoe 13. Cooler and thicker 13. Aa
Pahoehoe Aa
14. A volcano erupts explosively if its magma is high in silica. High-silica magma is _________ and _____________.
15. Explain what happens during an explosive eruption .
*Magma builds up in a volcano’s pipe, plugging it.
*Dissolved gases, water vapor cannot escape from the thick magma *Trapped gases build up pressure
16. Contrast the silica content of magma in quiet and explosive eruptions.
The magma of a quiet eruption is LOW in silica The Magma of an explosive eruption is HIGH in silica
Directions: Describe what the sizes are during the explosive eruptions.
Volcanic Ash Cinders Smallest pieces: fine, rocky particles that are as small as a speck of dust Pebble sized particles Bombs Larger pieces: can range from the size of a gold ball to the size of a car
18. How does an explosive eruption produce pyroclastic flow?
Thick, sticky lava builds up in a volcano’s pipe and plugs it. The trapped gasses build up pressure until they explode. The erupting gases force the magma out with great force which breaks the lava into fragments that quickly cool and harden in different sizes.
Directions:
19. Active 20. Dormant 21. Extinct
Geologists often use the terms active, dormant, or extinct to describe a volcano’s stage activity. Define the terms below.
Live volcano that is erupting or has shown signs that it may erupt again in the future A volcano that is sleeping; scientists expect it to awaken in the future and become active again A volcano that is dead, or unlikely to erupt again.
22. Name some warning signs that may signify a volcanic eruption may happen.
*Tiltmeters: Detect the slight surface changes in elevation and tilt caused by magna moving underground *Monitor gases escaping from a volcano *Monitor small earthquakes that occur around a volcano before an eruption *Rising temperatures in underground water