get ready for an eruption!!! volcanoessca.district70.org/.../28/62660550/pp-volcanoesp2.pdf ·...
TRANSCRIPT
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 2
TYPES (Landforms) -- Shield - layers of lava- gradual hill - quiet
-- Composite – Quiet/Explosive – layers ash and lava
-- Cinder Cone – Quick Formation - Explosive
LOCATION (s) -- Hot Spots
-- Ring of Fire (Convergent Boundary)
-- Divergent Boundary (MOR-Mid Oceanic Ridge)
-- Island Arc (Convergent oceanic/oceanic boundary)
LAVA FLOW -- Pyroclastic Flow – Cinder, Ash, Rock, Pumice, gases
-- Pahoehoe – fast – low silica- low viscosity
-- Aa – slow moving, high silica – high viscosity
TYPES AND LOCATIONS OF VOLCANOES
There are three different types of volcanoes. They are shield, composite and cinder cone. A shield volcano can cover a very large surface. A composite volcano is the most common volcano and its eruptions can be loud and explosive or quiet. A cinder cone is one that explodes cinders, ash and bombs. It grows quickly. Volcanoes can be found at hot spots, at convergent boundaries such as the ring of fire, and at divergent boundaries such as the mid oceanic ridge. Island Arcs can be formed when two oceanic plates converge. Awesome volcanoes form at various locations and they vary size and type.
T = VOLCANOES (CON’T) (PERIOD 2)
What determines Lava Flow?
-- Viscosity
-- Silica
-- Temperature
-- High Viscosity
High Silica, low Temp
--Low Viscosity
Low Silica, high Temp
ROCKS Formed (less important) *(usually high silica = lighter rock )
-- Pumice – Light and airy- from explosive eruptions(high silica content)
-- Obsidian – more dense and smooth (cools quickly- explosive eruptions)
-- Basalt – low silica lava flow (Pahoehoe)
-- Rhyolite – high silica content
-- granite – high silica content
T= VOLCANOES CON’T (PERIOD 2)
PARTS OF A VOLCANO
-- Stomach – Magma Chamber – Hot Magma
-- Esophagus – Pipe – regurgitation of magma
-- Throat – throat
-- Mouth - Vent
-- Ears – Side Vent
-- Opening around vent - Crater
-- Ash Cloud
-- Lava Flow
T= VOLCANOES CON’T
Life Cycle
--
--
--
PARAGRAPH ON VISCOSITY (PERIOD 2)
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.