formation of volcanoes Flashcards
(32 cards)
what are volcanoes
are vents in the Earth’s outermost layer called the crust that ejects volcanic materials such as molten rocks and gasses.
how many volcanoes are there worldwide
1500
philvocs meaning
the philippine institue of vocabology and seismology
The government agency that studies and monitors volcanic activities and earthquakes in the Philippines.
(PHIVOLCS)
how many active volcanoes listed in the ph
23 active volcs
how many potentially active listed in the ph
26 potential active volcs
how many inactive volcanoes in the ph
more than 300 named and unnamed inactive volcanoes in the PH
country part of the pacific ring of fire
philippines
○ A region of high seismic and volcanic activity in the basin of the Pacific Ocean.
● Pacific Ring of Fire
Outlines a series of boundaries where plates collide or move towards each other which create earthquakes and volcanoes.
Pacific Ring of Fire
what are trenches
Trenches
○ A long, deep depression which marks the place where plates collide.
Plate Tectonic Theory
States that the Earth’s mechanical outer layer (lithosphere) is divided into several
segments called tectonic plates.
what is the lithosphere
crust and upper mantle
tectonic plates
- segments of Earth’s crusts
- Floats on weak, semi-solid asthenosphere.
Asthenosphere
Semi-solid upper mantle
○ A proposed mechanism for plate motion
○ Happens in the mantle
○ This causes horizontal movement in the mantle which causes plates to move
towards or away from each other
Convection currents
- a method of heat transfer in which cold, dense material sinks while hot, less dense material rises.
○ Convection
the process in which when two plates converge, the denser plate
sinks under the other
subduction
the boundary where subduction happens
subduction zone
○ Oceanic plate (denser) collides with a continental plate (less dense), the oceanic
plate is forced under the continental plate and into the asthenosphere where
magma exists.
○ The addition of large volumes of seawater into the mantle allows faster heating of
mantle rocks into magma.
○ The magma then rises to the overlying continental plate thus forming volcanoes
along the plate margins
subduction / converging plates
○ A gap forms between two plates when they move away from each
other.
○ Magma from the mantle forcefully ruses through the gap forming volcanoes
calles ocean ridges.
○ Difficult since it happens in the seabed
Diverging Plates
Oceanic plate (denser) collides with a continental plate (less dense), the oceanic
plate is forced under the continental plate and into the asthenosphere where
magma exists.
○ The addition of large volumes of seawater into the mantle allows faster heating of
mantle rocks into magma.
○ The magma then rises to the overlying continental plate thus forming volcanoes
along the plate margins
converging plate or subduction
ocean floor volcanoes formed from diverging plates
ocean ridges
Volcanic eruptions under the ocean can create an island as the volcanic
materials may solidify above the water surface. Examples?
- Didicas volcanic islands in Cagayan Philippines
- Kavachi submarine Solomon Islands
