Volcanoes and Earthquakes Study Guide

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Volcanoes and Earthquakes test Bew c.

1. Where do earthquakes occur?
Earthquakes occur at breaks in the earth’s crust called the fault lines.
2. What causes Earthquakes?
Tectonic plates pushing, pulling, slipping past each other increasing the stress and causes elastic rebound to happen. During elastic rebound, energy is released and some travel as seismic waves, which cause an earthquake.

3. How do earthquake waves travel and what are the various types of waves?

Body waves travel through the earth’s body or inside.
P waves:
* through liquids solids and gases
* moves rocks back and forth
* fastest
S waves:
* shear rock side to side
* cant travel through liquids
* second fastest
Surface waves:
* move along earth’s surfaces
* slow and more destructive

4. How would a seismologist locate and earthquake?
They use a seismograph to record seismic waves and use the S-P time method to figure out the epicenter.

5. What is the basic structure of a volcano?
Vents, lava, magma chamber, and ash

6. What is the difference between an explosive and a non-explosive eruption?

Nonexplosive Eruptions
* Most common type
* Laval flows from them calmly. (can be huge amount)

Explosive Eruptions
* Rarer than nonexplosive eruptions
* Are very destructive as pyroclastic materials are flung into the air.

7. What materials erupt from a volcano?

Pyroclastic materials and lava.

Types of lava:
Aa
* Lava pours out quickly from a volcano and forms a hard crust Pahoehoe
* Lava pours out very slowly and forms a glassy surface. Pillow lava
* Lava that erupts underwater.
* Lava forms rounded lumps shaped like pillows.
Blocky Lava
* Lava does not travel far from the erupting vent.
* The lava forms jumbled heaps and rocks.

Types of pyroclastic materials:
Volcanic Bombs
* Large blobs of magma that harden in the air.
Lapilli
* Pebble like bits...
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