VolcanoesVolcanoes

4 types of lava4 types of lava

Lava is based on how it moves out Lava is based on how it moves out and away from the volcano.and away from the volcano.– Blocky lava: Cool and stiff, it does not Blocky lava: Cool and stiff, it does not

travel far from the volcano. It usually travel far from the volcano. It usually oozes out after an explosive eruption.oozes out after an explosive eruption.

– Pahoehoe (pah HOY HOY): slow flowing Pahoehoe (pah HOY HOY): slow flowing like wax dripping from a candle. It has a like wax dripping from a candle. It has a rope-like appearance.rope-like appearance.

4 types of lava4 types of lava

– Aa (AH ah): This lava has a jagged surface Aa (AH ah): This lava has a jagged surface and pours out of a volcano much quicker. and pours out of a volcano much quicker. It is brittle and hardens quickly, allowing It is brittle and hardens quickly, allowing for molten rock to flow underneath. It is for molten rock to flow underneath. It is named after the sound you would make if named after the sound you would make if you walked across it barefoot.you walked across it barefoot.

– Pillow lava: The result of lava erupting Pillow lava: The result of lava erupting underwater. The water causes rapid underwater. The water causes rapid cooling and results in bubble like pillows.cooling and results in bubble like pillows.

Can you identify these Can you identify these lavas?lavas?

Explosive lavaExplosive lava

If it doesn’t flow out of the volcano, it If it doesn’t flow out of the volcano, it gets blasted from the volcano. gets blasted from the volcano. These blasted pieces can range in These blasted pieces can range in size. size. Pyroclastic material (or pieces Pyroclastic material (or pieces shot from the volcano) are classified shot from the volcano) are classified by their sizes.by their sizes.

Types of pyroclasticsTypes of pyroclastics

There are 4 main types/sizes ejected There are 4 main types/sizes ejected from explosive eruptions:from explosive eruptions:– Volcanic blocks: Solid chunks of rock Volcanic blocks: Solid chunks of rock

blasted from the volcano, they are blasted from the volcano, they are basically chunks of the volcano top.basically chunks of the volcano top.

– Volcanic bombs: Large blobs of magma Volcanic bombs: Large blobs of magma that harden in the air. They often form that harden in the air. They often form tear-drop shapes as they fly through the tear-drop shapes as they fly through the air. They are larger than 64mm in air. They are larger than 64mm in diameter.diameter.

Types of pyroclasticsTypes of pyroclastics

– Cinders (or Lapilli (La pillee): Meaning Cinders (or Lapilli (La pillee): Meaning “little stones” in Italian), these are “little stones” in Italian), these are pebble-like pieces that range from 2mm pebble-like pieces that range from 2mm to 64mm.to 64mm.

– Volcanic Ash: Particles that are less than Volcanic Ash: Particles that are less than 2mm in diameter. Ash forms when 2mm in diameter. Ash forms when gases force magma to explode into tiny gases force magma to explode into tiny pieces.pieces.

Can you identify these Can you identify these pyroclastics?pyroclastics?

Types of VolcanoesTypes of Volcanoes

Shield VolcanoShield Volcano– Layers of lava from repeated non-Layers of lava from repeated non-

explosive eruptions.explosive eruptions.– Wide with a gentle slope.Wide with a gentle slope.– Often the tallest because it is always Often the tallest because it is always

increasing in sizeincreasing in size, never decreasing., never decreasing.

Types of VolcanoesTypes of Volcanoes

Cinder cone volcanoCinder cone volcano– Small volcanic cones made from its own Small volcanic cones made from its own

pyroclastic material.pyroclastic material.– Has a steeper slope with a narrower Has a steeper slope with a narrower

base.base.– They often erode quickly because they They often erode quickly because they

are not cemented down by lava.are not cemented down by lava.

Types of VolcanoesTypes of Volcanoes

Composite Volcano Composite Volcano (Stratovolcano)(Stratovolcano)– The most common type The most common type

of volcano.of volcano.– They form by explosive They form by explosive

eruptions followed by eruptions followed by lava flows.lava flows.

– Alternating layers of Alternating layers of lava and pyroclastics lava and pyroclastics form broad bases with form broad bases with steep sides.steep sides.

Famous VolcanoesFamous Volcanoes

Here is a list of Here is a list of famous volcanic famous volcanic eruptions in eruptions in historyhistory

Mt. VesuviusMt. Vesuvius

Perhaps the most famousPerhaps the most famous It completely buried the City of Pompeii It completely buried the City of Pompeii

in 79 A.Din 79 A.D Town was covered in 20 feet of ashTown was covered in 20 feet of ash Unknown diedUnknown died

Mount PeleeMount Pelee

Erupted in 1902Erupted in 1902 Destroyed the Town Destroyed the Town

of St. Pierreof St. Pierre Killed over 30,000 Killed over 30,000

(only 2 survived in (only 2 survived in the whole city)the whole city)

Only took 2 minutes Only took 2 minutes to destroy the whole to destroy the whole citycity

BeforeBefore

AfterAfter

KrakatauKrakatau

Largest explosion in recorded history Largest explosion in recorded history (heard 4000 miles away!)(heard 4000 miles away!)

Erupted in 1883 in Java/SumatraErupted in 1883 in Java/Sumatra Produced a tsunami that killed Produced a tsunami that killed

36,00036,000

TamboraTambora

Erupted in 1815 in IndonesiaErupted in 1815 in Indonesia Killed 10,000 immeadiatelyKilled 10,000 immeadiately 82,000 starved to death82,000 starved to death Caused worldwide issuesCaused worldwide issues

Mount St. HelensMount St. Helens

Erupted outside Erupted outside Seattle, Washington Seattle, Washington in 1980in 1980

Killed 65, most of Killed 65, most of swallowing hot ashswallowing hot ash

Destroyed 232 Destroyed 232 square milessquare miles