43 terms


Earth Science Volcanoes
Where are most of Earth's volcanoes found?
Volcanic belts form along the boundaries of Earth's plates.
How do hot spot volcanoes form?
A volcano forms above a hot spot when magma erupts through the crust and reaches the surface.
What is a volcano?
A weak spot in the crust where molten material or magma comes to the surface
Where are most volcanoes located?
Many of Earth's volcanoes are located along the boundaries of tectonic plates. The Ring of Fire is a belt of volcanoes that circles the Pacific Ocean.
What is a hot spot?
An area where material from deep within the mantle rises and melts, forming magma.
How does a hot spot volcano form?
A volcano forms above a hot spot when magma erupts through the crust and reaches the surface.
What features form as an oceanic plate moves across a hot spot?
When an oceanic plate moves along hot spots, they gradually form a series of volcanic mountains
Why is it helpful to know the physical and chemical properties of a substance?
Each substance has a particular set of physical and chemical properties. These properties can be used to identify a substance or to predict how it will behave.
What causes some liquids to flow more easily than others?
Because liquids differ in viscosity, some liquids flow more easily than others.
What factors determine the viscosity of magma?
The viscosity of magma depends upon its silica content and temperature.
How hot are magma and lava?
lava goes from 700-1200 degrees C.
retains heat-lava for months or years, magma for 1000s to millions
What is a physical property?
any characteristic of a substance that can be observed or measured without changing the composition of the substance.
What is a chemical property?
any property that produces a change in the composition of matter.
Is the boiling point of a substance a physical property or a chemical property?
physical property
Magma is a hot, liquid mixture that changes to solid rock when it cools and hardens. Which of these characteristics are physical properties?
liquid mixture and changes to solid rock when it cools then hardens
What is viscosity?
The resistence of a liquid to flow.
Which has a higher viscosity, a fast-flowing liquid or a slow-flowing liquid?
What can you infer about the amount of friction among the particles of a liquid that has low viscosity?
There is not a lot of friction at all
What two main factors affect magma's viscosity?
1) silica content
2) temperature
A lava flow cools as it moves away from the vent. How would this affect the surface appearance of the lava flow?
It would slow it because it's going to become rock so as it cools down, it begins to get harder and flows slower
Both pahoehoe and aa can come from the same volcano. Pahoehoe flows easily and hardens into a rippled surface. Aa hardens into rough chunks. Which type of lava has lower viscosity?
What happens when a volcano erupts?
When a volcano erupts, the force of the expanding gases pushes magma from the magma chamber through the pipe until it flows or explodes out of the vent.
What are the two types of volcanic eruptions?
Geologists classify volcanic eruptions as quiet or explosive.
What are a volcano's stages of activity?
Geologists often use the terms active, dormant, or extinct to describe a volcano's stage of activity.
"Pele's hair"
a type of rock formed from lava. Each strand is as fine as spun glass.
Lava begins as magma
which usually froms in the asthenosphere.
What happens to the pressure in magma as the magma rises toward the surface?
When a volcano erupts, the force of the expanding gases pushes magma from the magma chamber through the pipe until it flows or explodes out of the vent.
How does a volcano form?
A volcano forms where magma breaks through Earth's crust and lava flows over the surface.
What part of a volcano connects the vent with the magma chamber?
the pipe
What are the main parts of a volcano?
Magma chamber, Lava flow, Side vent, Pipe, Vent, Crater.
Describe the order of parts through which magma travels as it moves to the surface.
Magma chamber, side vent, pipe, vent, crater.
As a volcano erupts what force pushes magma out of a volcano onto the surface?
Dissolved gases under tremendous pressure are trapped in magma. The FORCE OF THE EXPANDING GASES pushes it through the pipe until it flows or explodes out of the vent.
What are two main kinds of volcanic eruptions?
Quiet and Explosive
What properties of magma help to determine the type of eruption?
The physical properties of its magma determine how a volcano erupts. Whether an eruption is quiet or explosive depends on the magma's silica content and viscosity.
What do lava flows made of pahoehoe and aa indicate about the type of volcanic eruption that occured?
What are the three stages of volcanic activity?
active, dormant, and extinct
Which is more likely to be dangerous a volcano that erupts frequently or a volcano that has been inactive for a hundred years? Why?
A volcano that has been inactive for a hundred years, because people near this volcano are unaware of the danger they could be in, and are unprepared.
How does volcanic ash cause damage?
Volcanic ash can bury entire towns, if it becomes wet, it can cause roofs to collapse
if a plane engine sucks it in the plane it could fall
eruptions can cause landslides and avalaunches of mud, melted snow, and rock.
How do geologists monitor volcanoes?
1. use tiltmeters and other instruments to detect slight changes in elevation and tilt caused by magma movement
2. monitor gases escaping volcano
3. temperature increase in underground water may be a sign that magma is nearing the surface
4. monitor earthquakes (triggered by upward movement of magma) that occur around a volcano
What landform do lava and ash create?
Volcanic eruptions create landforms made of lava, ash, and other materials. These landforms include shield volcanoes, cinder cones volcanoes, composition volcanoes and lava plateaus
How does magma that hardens beneath the surface create landforms?
Features formed by magma include volcanic necks, dikes, and sils, as well as batholiths and dome mountains.
What other distinctive features occur in volcanic areas?
Hot springs and geysers are types of geothermal activity that are often found in areas of present or past volcanic activity.
What type of volcano is formed from thin, low-silica lava?