1. Volcanic Activity

2. How Magma Reaches the Surface
Magma rises because magma is less __________ than the surrounding _________ material.
It will rise until it reaches the ___________ or becomes trapped beneath _________ of _________.

3. A Volcano Erupts
A volcano erupts when an opening develops in _________ _________ on the surface.
During a volcanic eruption, the _________ dissolved in __________ rush out, carrying the magma with them.
Inside a Volcano:
__________ ___________ – The pocket beneath a volcano where magma collects

4. ,
The magma moves through the _______, a long tube in the ground that connects the magma chamber to Earth’s surface.
__________ - an opening in the volcano where gases and molten rock leave.
__________ ________ – The area covered by lava as it pours out of a vent.
Crater – A _________-__________ area that may form at the top of a volcano around the volcano’s central _________.

5. Characteristics of Magma
__________ content, how __________ or _________ the magma is, temperature and silica contents are important factors as to the __________ of a volcanic eruptions.
The amount of ___________ in magma helps to determine how easily the magma flows. Silica is formed from the elements ___________ and ___________ and is abundant in the crust and ___________. The __________ silica content in magma the thicker the magma.

6. Types of Volcanic Eruptions
Silica content determines whether the volcanic eruption is ___________ or ___________.
Quiet Eruption:
A volcano erupts quietly if its magma flows easily.
Quiet eruptions produce two types of lava:
________________ – fast-moving, hot lava
_____ – cooler, slower moving lava

7. Explosive Eruptions:
If magma is __________ and __________, a volcano will erupt explosively.
The explosion will break the lava into ___________ that quickly cool and harden into pieces of different size called ___________.
Smallest pieces are called _________ (fine, rocky particles as small as a grain of sand), ___________ are pebble-sized particles and ___________ are larger pieces that range in size from a baseball to a car.

9. Stages of a Volcano
____________ – a volcano that is erupting or has shown signs that it may erupt.
____________ – sleeping and may become active in the future.
____________ – a volcano that is unlikely to erupt again.

10. Other Types of Volcanic Activity
Hot Spring – forms when ______________ heated by a nearby body of magma rises to the surface and collects in a natural _________.
Geyser – a fountain of ___________ and __________ that erupts form the ground.
_____________ ____________ – water heated by magma that provides a clean, reliable energy source.

11. Monitoring Volcanoes
Geologists have been somewhat successful in predicting eruptions. They use the same devices that are used to monitor earthquakes (______________, __________-___________ devices, etc.). Geologist will also monitor the small ____________ that normally accompany a volcano.

12. Volcano Hazards
Although quiet eruptions and explosive eruptions involve different volcano hazards, both types of eruptions can cause damage far from the crater’s rim.
Volcanic ash can bury entire towns, damage ___________, and car _____________. Eruptions can also cause ___________ and _______________.