Volcanoes

Cinder cone volcanoes produce ___________________ eruptions

explosive

Granitic lava produces __________________ eruptions

explosive

The more gas present, the greater the chance of a(n) __________________ eruption.

explosive

Lava flows can destroy property, start __________________, and release smoke, which pollutes the air.

fires

_________________ temperature and ground movement can also indicate that an eruption is near.

ground

Volcanic eruptions produce many ___________________ that can affect humans and wildlife

hazards

Volcanoes that form over localized areas of high heat instead of along plate boundaries are known as __________

hot spots

when eruptions occur at continental plate boundaries

hot spots form

Most of a volcano's magma cools underground, forming ___________________ volcanic features

intrusive

magma

is molten rock

When two oceanic plates are pushed together, an ______ forms

island arc

magma rises to the surface because

it is less dense than the rock that rises through it

A __________________ is a rapidly flowing mixture of volcanic debris and water.

lahar

Falling ___________________ forms a distinctly steepsided, coneshaped landform.

lava

_________ form when highly viscous granitic lava piles up to form a rounded feature.

lava dome

__________________ can occur from explosive or quiet volcanic eruptions.

lava flows

______ are hollow channels that form when the surface of swiftly moving lava cools and hardens first.

lava tubes

The __________________ of large amounts of volcanic ash can damage buildings.

layers

Magma with less silica and more iron and magnesium has __________________ viscosity, meaning it flows easily.

less

Magma with a __________________ percentage of silica is basaltic.

low

vent

oval or circular opening of a volcano through which heat escapes

A volcanic arc is a string of volcanoes that form ______ to a continent's leading edge.

parallel

Basaltic lava that flows underwater forms bubblelike __________________ lava.

pillow

Technologies such as __________________ allow volcanoes to be monitored from space.

satellite imaging

A __________________ is a huge, gently sloping landform composed of basaltic lava.

shield

_________________ of volcanic eruptions save lives and can help avoid costly repairs.

signs

Scientists make predictions about a volcanic eruption's energy from the percentage of __________________ and oxygen in magma.

silica

Lava flows are usually __________________ giving people time to get out of their paths.

slow

Magma with a high percentage of silica is __________________.

slow moving

crater

steep walled depression around the vent

volcanoes occur where...

the heat from Earth's interior is high

Basaltic lava pours over the __________________ and runs down the sides of the volcano.

top

divergent plate volcanoes

two plates pull apart

convergent plate volcanoes

two plates push together

when eruptions occur in the ocean they cause

vents

Basaltic lava has a low __________________, is thinner and more fluid, and tends to flow quietly.

viscosity

Magma with a high silica content has a high __________________, meaning it is thick and slow moving.

viscosity

Clouds of __________________ contain tiny particles of sharp mineral and glasslike particles.

volcanic ash

_____ magma that has hardened inside the vent.

volcanic neck

_______ form when erosions wears away the volcano,

volcanic neck

Igneous rock

when magma rises to the surface

__________________ is the most common dissolved gas in magma; carbon dioxide, sulfur dioxide, and hydrogen sulfide are also present.

Water

Two types of magma and lava are __________________ and granitic

basaltic

_______ lava develops a smooth skin and forms ropelike patterns;

basaltic

________ are the largest intrusive feature, forming when magma cools and solidifies before reaching the surface.

batholiths

________ form when magma is forced into cracks parallel to rock layers.

batholiths

Shield volcanoes develop from the buildup of __________________ of gently flowing lava.

bent

The location, type, and amount of gases such as __________________ can signal an eruption.

carbon dioxide

A ___________________ is composed mainly of solid fragments called tephra

cinder cone

A ___________________ is composed of alternating layers of lava and tephra

composite

Volcanic ash can bury plants, animals, and food sources and __________________ water

contaminate

volcanoes can occur at _____ plate boundaries

convergent

Two kinds of plate volcanoes

convergent and divergent

Lahars can quickly __________________ human and wildlife habitats

cover

________ is a large, sunken crater that forms when the top of a volcano collapses into the nearly empty magma _______

A caldera, chamber.

The ___________ of magma controls a volcano's eruption and lava flow

Composition

__________________ can be a silent hazard to humans and wildlife.

Gas emissions

Granitic lava has a __________________ viscosity, is sticky and lumpy, and tends to trap gases.

High

An island arc is a long, curved string of volcanic _____

Islands

__________________ occurring from eruptions can trigger lahars.

Landslides

Volcano

Occurs when magma reaches Earth's surface on land or underwater.

__________________ are fastmoving bodies of hot gases and solids.

Pyroclastic flows

_______ lava is stiffer and more slowmoving

granatic

Sulfur dioxide and hydrogen sulfide gases can form __________________.

acidic precipitation

Intensely hot gas within the flow can contaminate surrounding ______

air

Layers accumulate through ___________________ quiet and explosive eruptions.

alternating

It is possible to __________________ volcanic eruptions by monitoring certain activity.

determine

Pyroclastic flows can __________________ everything in their paths

devastate

________ and ______ form when magma is forced into cracks that cut across rock layers.

dikes and sills

Composite volcanoes often occur at ___________________ plate boundaries and form tall, majestic mountains

divergent

fissure eruptions occur at...

divergent plate boundaries, forming new crust.

Before an eruption, small __________________ usually occur, ranging from magnitude 1 to 3.

earthquake

The amount of __________________ and magma temperature also affect eruption.

gases

California volcanoes formed at convergent plate boundaries as part of _____________

majestic mountains

heat and pressure in the earth's interior cause rock to...

melt, forming magma

fissure eruption

occurs when magma escapes from elongated cracks in the crust

When an oceanic plate sinks beneath a continental plate, a _________ forms

ocean trench

Scientists use __________________ and global positioning systems to observe slight changes in land temperature, elevation, and slope.

remote sensing