Volcanoes Presentation

Volcanoes Presentation with material chiefly drawn from the Geological Society of the UK.
Presented to Reddam House Waterfall learners on 14 March 2022

2. Hot rock
Cool rock
Active
Dormant
Extinct
z
z
z

3. Volcanic bombs: large lumps of rock and molten
blobs of magma thrown out from the volcano
Ash, steam & gas: material erupted from the volcano
Geyser:vent that shoots steam and boiling water
into the air
Sill: flat sheet of igneous rock formed underground
Ash, steam & gas
Crater
Secondary vent
Volcanic bombs
Lava
Sills
Magma chamber
Geysers
Conduit
Main vent
Dykes

4. •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

5. 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 rigidand
brittleso can fracture and
buckle
•Asthenosphere is solidrock
but is plasticand can flow

7. Pacific plate

8. Plates moving AWAY
from each other
Volcanoes
Magma
New ocean
crust
David Karnå/CC by 3.0
Iceland
Lithosphere
Asthenosphere
(lower mantle)

9. Magma
Plate melts
Volcano
Plate is subducted
Oceanic and
Continental plates
Mount St. Helens,
Washington, USA
Oceanic crust
~2.9 g/cm
3
Continental crust
~2.7 g/cm
3

10. Oceanic and
oceanic plates
Older
oceanic plate
Younger
oceanic plate
Oceanic
island arc
Magma
Plate melts
Plate is subducted
Ocean trench
Mount Mayon,
Philippines

11. Magma
Hot spot
Active volcano
Older extinct volcanoes
Plate moving
over hotspot
Kilauea, Hawaii
Plate moving
OVER a HOTSPOT
Kilauea, Hawaii

12. Hawaii
Emperor
Seamount chain
43Ma
78Ma

13. Lava fountain, Hawaii
Ash cloud, Aleutian Islands
Volcanic bomb
Effusive
Explosive
Pyroclastic flow,
Monserrat
(British Geological Survey)
Lava lake, Nyiragongo

14. Effusive
Effusive

15. Explosive
Explosive

16. Lava lake, Nyiragongo

17. Olympus Mons on Mars
Shallow slopes
made from lava
Runny basalt
magma
Kilauea lava lake,
Hawaii
Wolf Volcano, Galapagos
Islands
ErtaAle Volcano, Ethiopia
Photo: filippo_jean/CC-By-2.0

18. Steep slopes
made from
lava and ash
Sticky magma
Mount St. Helens,
Washington, USA
Mount Fuji, Japan
MayonVolcano,
PhilippinesCotopaxi, Ecuador

19. ´A´a lava, Guatemala
Photo: Librex/CC-By-2.0Pahoehoelava,
Hawaii
Columnar joints,
Isle of Mull
Pillow lava,
Cornwall

20. IGNEOUS
ROCKS

22. Magma
Rock images: Sandatlas.org
Basalt
columns,
Isle of Mull
Basalt
Andesite
Basalt with
olivine crystals
Obsidian
Pumice

23. Magma
Rock images: Sandatlas.org
Volcanic
bomb
TuffASH

24. Gabbro under the
microscope
Gabbro
Granite
MAGMA
Diorite
Rock images: Sandatlas.org

25. VOLCANO
CASE STUDIES

26. •Mid Atlantic Ridge –
divergent plate
boundary
•North American and
Eurasianplates moving
apart at 25mm/year
•Iceland also lies above a
‘hotspot’
•Eyjafjallajökull is in
Iceland's Eastern
Volcanic Zone
•200km thick ice cap

27. David Karnå/CC by 3.0
Fissure eruption at
Fimmvörðuháls
Ash column after explosive
eruption
Explosive eruption at
Eyjafjallajökull
20
th
March 2010
10km high plume
Boaworm/CC by 3.0

28. •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. •Mount Nyiragongois in the
Democratic Republic of Congo
•Part of East African Rift Valley, a
developing divergent plate
boundary
•Crater contains persistent lava
lake
•Thelava emitted in eruptions at
Nyiragongois often
unusuallyfluid (nephelinite -
very low SiO2 content)

31. Wikimedia/Caitjeenk/CC-By-3.0

32. •Nyiragongoerupted on 17
th
January 2002
•13km fissure opened up on the south side of the
volcano
•Lava flows reached speeds of 60km/hrin the direction
of Goma and Lake Kivo
•14-34 million m
3
of lava
•Eruption of lava stopped after ~12 hours but lava
continued to flow towards and into Lake Kivofor a 3
days
•45 fatalities in first 24 hours due to lava flows and CO
2
asphyxiation

33. THE PRESENTER
A huge thank you and acknowledgements to the Geological
Society of the UK from which this material was chiefly drawn
https://twitter.com/JAHC1
https://www.linkedin.com/in/jamesahcampbell/
https://www.slideshare.net/JamesAHCampbell1
https://www.youtube.com/JamesCampbell_JAHC
James Campbell has spent over 35-years in the diamond industry in a variety of
leadership roles both in major and junior companies. He is currently Managing
Director of Botswana Diamonds plc. Previously he held leadership roles at
Rockwell Diamonds Inc, Stellar Diamonds plc, Lucara Diamond Inc, African
Diamonds plc, West African Diamonds plc, Shefa Gems and De Beers where he
spent over 20-years with notable appointments including General Manager
Exploration and Nicky Oppenheimer's Personal Assistant. James is also Chairman
of the leadership development Non-Profit Organisation Common Purpose SA.
James holds a degree in Mining & Exploration Geology from the Royal
School of Mines (Imperial College, London) and an MBA with
distinction from Durham University. James is a Fellow of the IOM
3
,
SAIMM, GSSA and IODSA. He is also a C.Eng (UK), C.Sci (UK) and
Pr.Sci.Nat.