Volcanoes

1. The minimum number of seismograph stations necessary to determine the location of an earthquake is .

2. Which point below is the focus of the earthquake?

3. Which point below is the epicenter of the earthquake?

A

B

3

B

A

ReviewReview• P-waves• S-waves• L-waves• Epicenter• Focus• Trilateration

VolcanoesVolcanoes Any opening in the Earth’s

crust through which magma reaches the surface

The openings are called vents

VolcanoesVolcanoesWhen magma reaches the surface it is called lava

Hills or mountains are a result of this process

VolcanoesVolcanoes• 3 types of volcanoes

Shield VolcanoesShield VolcanoesBroad and roundedMade from stacks of runny basaltic lava

Mauna Loa, Hawaii

Kilimanjaro, Africa

Cinder ConeCinder Cone Smallest, most abundant Violent eruptions with lots of

ash Active for short time, then

become dormant

Paricutin, MexicoParicutin, Mexico

Composite ConeComposite Cone Steep sided volcano made of

alternating layers of cinders and lava

Usually found along plate boundaries

Mount Fuji, JapanMount Fuji, Japan

OccurrencesOccurrences

Most volcanoes occur at or near subduction zones

Arenal Volcano, Costa RicaArenal Volcano, Costa Rica

OccurrencesOccurrencesSome occur near divergent plate boundaries

IcelandIceland

OccurrencesOccurrencesSome occur in the middle of plates

Hot spot volcanoes

Mauna Loa, Hawaii

Kilimanjaro, Africa

EruptionsEruptions

• Different types of eruptions

Explosive Quiet

Different types of Lava Different types of Lava

Aa Lava

Pahoehoe LavaPahoehoe Lava

Skylight