get ready for an eruption!!! volcanoessca.district70.org/ourpages/auto/2012/11/28/40903445/pp...why...
TRANSCRIPT
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
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
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.