4. Ash, steam & gas
Crater
Secondary vent
Volcanic bombs
Lava
Sills
Magma chamber
Geysers
Conduit
Main vent
Dykes
5. • Magma collects in
magma chamber
• As magma is added the
pressure increases
causing fractures
• Magma is less dense than
surrounding solid rock
so rises
• Erupts on the surface
through a volcano as
lava, ash and gas
6. Outer
core
(liquid)
Inner
core
(solid)
• Plates are made from the
lithosphere
• The lithosphere is broken
up into tectonic plates
which move around on top
of the asthenosphere
• Lithosphere is rigid and
brittle so can fracture and
buckle
• Asthenosphere is solid rock
but is plastic and can flow
9. Plates moving
AWAY from each
other
Magma
Volcanoes
New ocean
crust
David Karnå / CC by 3.0
Iceland
Lithosphere
Asthenosphere
(lower mantle)
10. Plate melts
Volcano
Plate is subducted
Oceanic and
Continental plates
Mount St. Helens,
Washington, USA
Oceanic crust
~2.9 g/cm³
Continental crust
~2.7 g/cm³
Magma
11. Oceanic and
oceanic plates
Older
oceanic plate
Younger
oceanic plate
Oceanic
island arc
Magma
Plate melts
Plate is subducted
Ocean trench
Mount Mayon,
Philippines
18. Shallow slopes
made from lava
Runny basalt
magma
Kilauea lava lake,
Hawaii
Wolf Volcano, Galapagos
Islands
Erta Ale Volcano, Ethiopia
Photo: filippo_jean/CC-By-2.0
Olympus Mons on Mars
19. Steep slopes
made from
lava and ash
Sticky magma
Mount St. Helens,
Washington, USA
Mount Fuji, Japan
Mayon Volcano,
Philippines
Cotopaxi, Ecuador
20. ´A´a lava, Guatemala
Photo: Librex/CC-By-2.0
Pahoehoe lava,
Hawaii
Pillow lava, Cornwall
Columnar joints, Isle of Mull
27. • Mid Atlantic Ridge –
divergent plate
boundary
• North American and
Eurasian plates moving
apart at 25mm/year
• Iceland also lies above a
‘hotspot’
• Eyjafjallajökull is in
Iceland's Eastern
Volcanic Zone
• 200km thick ice cap
28. David Karnå / CC by 3.0
Fissure eruption at
Fimmvörðuháls
Explosive eruption at
Eyjafjallajökull
20ᵗʰ March 2010
10km high plume
Boaworm / CC by 3.0
29. • European airspace was closed from 15-21 April 2010.
107,000 flights were cancelled, airline industry lost£1.1
billion (International Air Transport Association)
• Many industries relying on air freighted products were
badly affected shortages of imported fruits,
flowers and electronic hardware
• River levels raised by 3m
• Agricultural land, roads, bridges and buildings damaged
by flooding
• 800 people were evacuated
30.
31. • Mount Nyiragongo is in the
Democratic Republic of Congo
• Part of East African Rift Valley, a
developing divergent plate
boundary
• Crater contains persistent lava
lake
• The lava emitted in eruptions at
Nyiragongo is often
unusually fluid (nephelinite - very
low SiO2 content)
