120 likes | 125 Views
Volcanic Activity. 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 _________. A Volcano Erupts.
E N D
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 _________.
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
, • 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 _________.
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.
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
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.
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.
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.
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.
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 _______________.