Transcript Volcano Research Paper

Volcano Research Paper
• Intro: define volcano & define tectonic plate
boundaries.
• *many volcanoes form on plate boundaries
• *a few processes cause rock to melt, forming
magma
• *because magma is not as dense as the rock
around it, it moves up & erupts to form a volcano
• What is a volcano? A crack in the Earth’s surface
where melted rock (lava/magma) and gases
pass.
Where Volcanoes Form
Divergent Boundary
• Boundary between two tectonic plates that are
pulling away from each-other.
• Molten rock also forms submarine volcanoes
• The denser plates forms to make a trench
• Fissures form
• Mid-ocean ridges are formed
• Molten rock flows through the fissures onto the
ocean floor.
• Divergent boundaries under water chains known
as mid-ocean ridges.
Where Volcanoes Form Cont.
Convergent Boundary
• A boundary when plates collide and it gets denser and
bends
• One plate moves under the other (this is called
subduction)
• As a plate moves down it gets greater heat & pressure
• Plates release fluid which causes surrounding rock to
melt
• When subduction occurs, the denser plate moves
underneath the lighter plate---creating a trench
• As the plates subduct, the rock receives greater
pressure / this pressure causes the plate to give off fluid.
Where Volcanoes Form Cont.
Hot Spots
• Places that experience a great deal of volcanic
activity, but do not lie on plate boundaries
• Sit over columns of hot rock that come up that
come up through the Earth’s mantle
• The columns do not move and are called mantle
plumes
• The plate slips over this column of hot rock, and
as the magma comes up, it creates a chain of
volcanic islands. The Hawaiian Islands are an
example of this
How Magma Forms
• Magma is made deep in the Earth’s crust and in the upper sections
of the mantle
• Temperature is high and there is a great deal of pressure
• When temperature /pressure change, magma forms. Specifically
temp. up and pressure down---makes rock melt
• Water can also make the melting temp. of rock lover, causing it to
melt
• Temperature causes some minerals to melt and form magma
• When pressure on rock goes down, it creates space around rock.
The rock then expands & melts, creating magma adding fluids
• In the lithosphere of oceanic plates, there is sediment and volcanic
rock that holds water and other fluids
• When an oceanic plate subducts, the fluids come into contact with
the surrounding rock
• When fluids enter, the melting temp. decreases and rock begins to
melt.