VOLCANOES Get Ready for an ERUPTION!!!

VOLCANOS

Three Types of Volcanos

Shield

Cinder Cone

Composite

LAND FORMATIONS FROM LAVA & ASH

Shield Volcano Created by hot spots

Gently sloping

Cinder Volcano Steep

Cone-shaped hill/mountain

Composite Volcano

Tall, cone-shaped mountain Alternating layers of ash and lava

SHIELD VOLCANO

http://www.earthonlinemedia

.com/images/lithosphere/vol

canism/shield_volcano_2.gif

SHIELD VOLCANO

http://www.earthonlinemedia

.com/images/lithosphere/vol

canism/shield_volcano_2.gif

CINDER CONE

Ecuador volcanoes, Guagua Pichincha volcano

Ash cinder and bombs erupt

explosively to form a cone shaped hill http://www.youtube.com/watch?v=aS_xl3nu_mY&NR=1&feature=endscreen

COMPOSITE

http://www.youtube.com/watch?v=1u1Ys4m5zY4

Quiet eruptions alternate with explosive forming

layers of lava ash.

http://facweb.stvincent.edu/academi

cs/pathways/science/volcanoes.htm

WHAT IS A VOLCANO?

A weak spot in the crust where molten material, or magma, comes to the surface

Magma- molten mixture of rock-forming substances, gases & water from the mantle

Lava- Magma that reaches the surface

WHERE ARE VOLCANOES LOCATED?

Volcanoes can be found: Diverging Plate boundaries

(mid-ocean ridge)

Converging plates with subduction zones Oceanic plate vs. oceanic plate

Oceanic Plate vs. Continental plate

Hot Spots Area where magma from deep within the mantle melts

through the crust like a blow torch Example: Hawaiian Islands

WHAT IS THE RING OF FIRE?

Ring of Fire

A circular pattern located around the pacific ocean along the plate boundaries where volcanoes are more common

RESULTS OF VOLCANOES

Are constructive: add new rock to existing land

form new islands

Can be destructive explosive eruptions changes the landscape of

and around the volcano

ERUPTIONS

Why do volcanoes erupt? Less dense magma seeps upward through cracks and

creates volcanoes

Gas in the magma is trapped and builds pressure

Closer it gets to surface the less pressure it has and the gases separate (bubbles)

Gases dissolve on the surface and magma is carried out

TYPES OF ERUPTIONS

2 types:

Quiet

Lava moves steadily and easily

Explosive

Thick, sticky lava plugs vent like a cork and builds up pressure

Explodes and releases pyroclastic flow Volcanic ash: fine, rock particles

Cinders: pebble sized particles

Bombs: baseball to car sized particles

LAND FORMATIONS FROM LAVA & ASH

Shield Volcano Created by hot spots

Gently sloping

Cinder Volcano Steep

Cone-shaped hill/mountain

Composite Volcano Tall, cone-shaped mountain

Alternating layers of ash and lava

SHIELD VOLCANO

http://www.earthonlinemedia

.com/images/lithosphere/vol

canism/shield_volcano_2.gif

CINDER CONE

Ecuador volcanoes, Guagua Pichincha volcano

Ash cinder and bombs erupt

explosively to form a cone shaped hill http://www.youtube.com/watch?v=aS_xl3nu_mY&NR=1&feature=endscreen

COMPOSITE

http://www.youtube.com/watch?v=1u1Ys4m5zY4

Quiet eruptions alternate with explosive forming

layers of lava ash.

http://facweb.stvincent.edu/acade

mics/pathways/science/volcanoes.h

tm

WHERE ARE VOLCANOES LOCATED?

Volcanoes can be found:

Diverging Plate boundaries (mid-ocean ridge)

Converging plates with subduction zones

Oceanic plate vs. oceanic plate

Hot Spots

Area where magma from deep within the mantle melts through the crust like a blow torch

Example: Hawaiian Islands

TYPES OF ROCKS PRODUCED

Type of lava produces different types of rocks

Slower Flowing, Thicker, sticky, lighter

colored

Rhyolite, Pumice, obsidian

flows readily, dark colored basalt

SILICA CONTENT DETERMINES ROCK

High Silica –

thicker, sticky, lighter colored

Rhyolite, Pumice, Obsidian

Low silica lava

flows readily, dark colored

Basalt

TYPE OF FLOW

Quiet vs. Explosive – determined by

Percentage (amount) of silica (material made from the elements oxygen and silicon)

STAGES OF A VOLCANO

Active: (live) erupting or has shown signs that it may erupt In the near future

Dormant: (Sleeping) is not currently erupting but may/can erupt in the future

Extinct: (dead) unlikely to erupt again

OTHER VOLCANIC ACTIVITY

Hot springs

Groundwater is heated by near by magma rising to the surface and collects in natural pools

OTHER VOLCANIC ACTIVITY

Geyser

Rising hot water and steam that gets trapped underground and builds pressure until it sprays to the surface

VOLCANO GAMES

http://w4.nkcsd.k12.mo.us/~mkurbin/ptrevgm

s.htm

LAND FORMATIONS FROM LAVA & ASH

Lava Plateaus

Lava moves far from the volcano before cooling which forms high plateaus

Calderas

Huge hole left by the collapse of a volcanic mountain

All magma has been emptied leaving a hollow shell that collapses

LAND FORMATIONS FROM MAGMA

Volcanic Neck: magma hardens in the volcanoes pipes and the soft rock wears away

Dike: magma that was forced across rock layers hardens and the soft rock wears away

Sill: magma that squeezed between rock layers hardens and the soft rock wears away

LAND FORMATIONS FROM MAGMA

Batholith

Mass of rock formed when a large body of magma cools in the crust

Dome Mountains

Rising magma is blocked by horizontal rock layers and forces the rock layers to bend upward into a dome shape and then the soft rock wears away

T= VOLCANOES – PERIOD 6

TYPES -- Cinder Cone – quick to form- explosive

-- Shield – quiet- wide gently sloping (layers)

-- Composite – quiet or explosive – long time to develop

-- Lava Plateaus

--- Calderas –

--- Vertile Soil

LOCATION (s) -- Divergent Boundary – (MOR)

-- Hot Spots - Hawaii

-- Convergent Boundaries – Island Arcs – Oceanic/Oceanic Crust

Ring of Fire – Continental/Oceanic Crust

TYPES of LAVA FLOW Shield–

Pahoehoe – fast moving, low silica, low viscosity, temp high

Aa – higher viscosity, higher silica, cooler temp, slower moving

Composite/Cinder Cone Pyroclastic – explosive, ash, rocks, gases, cinders, bombs

T= VOLCANOES CON’T (PERIOD 6)

What determines Lava Flow?

-- Viscosity

-- Silica

-- Temperature

-- High Viscosity

High Silica, low Temp

--Low Viscosity

Low Silica, high Temp

ROCKS Formed (not as important) (usually higher silica = ligher rock but…

-- Basalt – low silica lava flow

-- Granite – higher silica

-- Rhyolite – higher silica

--Pumice – formed quickly with explosive volcano – airy

-- obsidian – glassy black – formed in high silica high viscous magma cools

quickly without crystallizing

T = VOLCANOE’S

PARTS OF A VOLCANO

-- Magma Chamber - Stomach

-- Pipe - Esophagus

-- Throat - throat

-- Vent - Mouth

-- Crater – lips

-- Side vent – ears, eyes, and bum

-- Lava Flow -throw up

-- Ash Cloud – sneeze

T = VOLCANOE’S

Geothermal Activity

Magma a few km underneath the earth’s surface heats water underground

Hot Springs – water above ground that has been heated by the magma below earths surface

Geysers – old faithful – the steam from the underground water heated by magma builds up pressure and explodes above earth’s surface.

Geothermal Energy –water heated by magma and can be used as an energy source. (i.e. similar to a windmill turning a turbine—water can create steam to turn a turbine and create energy)

VISCOSITY BY PERIOD 6

Lava is a unique mixture of chemicals that flow out of a volcano. The viscosity of lava flow is determined by temperature and silica content. What is viscosity? Well, it is the resistance of a liquid to flow. There is high viscosity and low viscosity. Low viscosity has a low silica content and high temperature. High viscosity has a high silica content and a low temperature. A type of lava flow that has low viscosity is Pahoehoe. It is a fast moving lava. Aa has high viscosity because it has high silica content and lower temperature. Aa is a slower moving lava. Pyroclastic has a high silica content and low temp. It is explosive. There are many lava flows and they have unique characteristics.

Tuesday - Write 5 complete sentences regarding the viscosity of lava flow. HINT— 1 What determines it! –

2 What causes low viscosity?

3 What causes high viscosity?

4 What type of lava flow has high viscosity?

5 What type of lava has low viscosity

Flow is determined by viscosity. Viscosity is determined by silica and temperature. Low amounts of silica causes low viscosity. Higher amounts of silica causes higher viscosity. Lower temperatures cause higher viscosity. Higher temperatures cause lower viscosity. Pyroclastic flows are high in viscosity. Pahoehoe and Aa have lower viscosity. Pahoehoe is less viscous than Aa. As you can see, some lava flow vary in viscosity.