This is a presentation on the volcanoes as studied in Geography, Geology and Geo-morphology.

1. Group E
Department of Geography and Environmental Science
Begum Rokeya University, Rangpur

2. Presentation on
Volcano, Types and volcanic
landscape

3. Group E
Name ID number
Firoj Mahmud 1511005
Juthika Roy 1511012
Arnika Afroj 1511019
Md. Rafsan Jani 1511027
Asmaul Husna 1511034
Razia Zaman Tonnita 1511043
Bishal Roy 1411011
Group E

4. Presentation Outline
Aims and Objectives
Methodology
Introduction
Definition of volcanoes
Components of volcanoes
Classification of volcanoes
Causes of volcanoes
Volcanic environment
Volcanic materials
World distribution of volcanoes
Hazardous effects of volcanoes
Volcanic landscape
Conclusion
References

5. Aims &
Objectives
i. To know about the volcanoes.
ii. To know about the components of
volcanoes.
iii. To know about the different types of
volcanoes.
iv. To know causes of volcanic eruption.
v. To know the volcanic environments.
vi. To know volcanic materials.
vii. To know hazardous effects of volcanic
eruptions.
viii. To know different types of volcanic
landscape.

6. Methodology
Data
collection
method
Internet
Books &
journals
Data
presentation
method
Map Photograph Flow chart

7. Introduction
A volcano is a mountain that opens downward to a pool of molten rock below
the surface of the earth. When pressure builds up, eruptions occur. Gases and
rock shoot up through the opening and spill over or fill the air with lava
fragments. Volcanoes are formed when magma from within the Earth's upper
mantle works its way to the surface. Volcanic landscape is an environment in
which molten rock acts as a geomorphic agent. The process is called 'volcanism'
and results in the molten rock being forced into the earth’s crust or out onto the
surface of that crust (the earth’s surface). Volcanism produces landforms that
are: intrusive features, found underneath the earth’s surface (for example,
dykes); extrusive features, found above the earth’s surface (for example, a
volcanic cone).

8. Definition of volcanoes
According to A. Holmes and D.L. Holmes
A volcano is essentially a fissure or vent,
communicating with the interior, from which flows of
lava, fountains of incandescent spray or explosive
bursts of gases and volcanic ashes are erupted at the
surface.
A volcano is a hole within the earth’s crust in which
steam, gases and molten rock spew out
According to McLean and Lockridge

9. Summit
Ash
Throat
Conduit
Ash Cloud
Vent
Lava
Crater
Sill
Magma
Components of volcanoes
Reference: www.usgs.gov.us

10. Classification of Volcanoes
Classification
On the basis of
mode of eruption
Central eruption
type or explosive
eruption type
Fissure eruption
type or quiet type
On the basis of
periodicity of
eruption
Active volcanoes
Dormanat
volcanoes
Extinct
volcanoes

11. Central eruption type or explosive
eruption type
Hawaiian type
Strombolian type
Vulcanian type
Plinian type
Visuvius type
Fissure eruption type or quiet
eruption type
Lava flood or lava flow type
Mud flow type
Fumaroles type
Classification on the basis of mode of eruption

12. Some examples of Central eruption type volcano
Hawaiian Strombolian
PliniaanVulcanian https://en.wikipedia.org/wiki/Volcano

13. On the basis of periodicity of eruption
a) Active Volcanoes
Active volcanoes which constantly ejects volcanic lavas, gases, ashes
and fragmental materials. Most scientists consider a volcano active if it
has erupted in the last 10,000 years
Reference: www.3dgeography.co.uk/what-is-a-volcano

14. b) Dormant volcanoes:
Dormant volcanoes are the volcanoes that are quiet, but might possibly
erupt again. A dormant volcano is "sleeping," but it could awaken in the
future. Dormant volcanoes include those which have not erupted in the
past 10,000 years.
Reference: www.3dgeography.co.uk/what-is-a-volcano

15. c) Extinct Volcanoes
Extinct volcanoes are those that scientists consider unlikely to erupt
again because the volcano no longer has a magma supply. Some
volcanologists refer to extinct volcanoes as inactive, though it is
now more commonly used for dormant volcanoes once thought to be
extinct.
Reference: www.3dgeography.co.uk/what-is-a-volcano

16. Causes of volcanic eruption
 Hot, molten rock (magma) is buoyant (has a lower density than the surrounding rocks) and will rise
up through the crust to erupt on the surface.
 Same principle as hot air rising, e.g. how a hot air balloon works
 When magma reaches the surface it depends on how easily it flows (viscosity) and the amount of
gas (H2O, CO2, S) it has in it as to how it erupts.
 Large amounts of gas and a high viscosity (sticky) magma will form an explosive eruption!
 Think about shaking a carbonated drink and then releasing the cap.
 Small amounts of gas and (or) low viscosity (runny) magma will form an effusive eruption
 Where the magma just trickles out of the volcano (lava flow).
https://en.wikipedia.org/wiki/Volcano

17. Volcanic environment
 In an island-arc environment, volcanoes lie along the crest of an arctuate.
 In an oceanic environment, volcanoes are aligned along the crest of a broad
ridge that marks an active fracture system in the oceanic crust.
 In the continental environment, volcanoes are located unstable, mountainous
belts that have thick roots of granite or granite like rock.

18. Volcanic materials
Volcanic materials discharged during eruptions include-
 Gases and vapors
 Lavas
 Fragmental materials
 Ashes
https://en.wikipedia.org/wiki/Volcano

19. Gases and Vapors
Volcanic eruptions emit water vapor and toxic gases into the atmosphere. Gases
emitted from an erupting volcano are:
 Carbon dioxide (CO2) – Lethal if trapped at low level.
 Sulfur dioxide (SO2) – Irritating to eyes, skin and respiratory system.
 Hydrogen sulfide (H2S) – very toxic in high concentrations.
 Hydrochloric acid (H2SO4) – Lethal.
 Carbon monoxide (CO) – Toxic.
Reference: www.usgs.gov.us

20. Lavas and magma
Magma is composed of molten rock and is stored in the Earth's crust. Lava is
magma that reaches the surface of our planet through a volcano vent. Lava flow,
Hawaii. Lavas and magmas divided on the basis of silica percentage into two
groups.
i. Acidic magma
ii. Basic lava
https://en.wikipedia.org/wiki/Volcano

21. Fragmental materials
Fragmental materials thrown during volcanic eruption (explosive type) are
grouped into three categories:
 Essential materials included consolidated forms of live lavas. These are also
known as tephra.
 Accessory materials include dead lava.
 Accidental materials include fragmental materials of crustal rocks.

22. World Map of Volcanoes
Reference: www.usgs.gov.us

23. Hazardous effects of volcanic eruptions
› Eruptions occurring close to human settlements may spill and destroy lives and
property. People often have to be evacuated.
› Ash discharged very high into the stratosphere can have negative
consequences on the ozone layer.
› Landscapes and natural sceneries can be destroyed.
› Ash and mud can mix with rain and melting snow, forming lahars. Lahars are
mudflows flowing at very fast pace.
Reference: www.usgs.gov.us

24. Landscape
Extrusive
Intrusive
Volcanic landscape
• Elevated forms
• Depressed form
From Explosive
type of
Eruptions
• Lava plateau and
domes
• Lava plains
From fissure
eruptions
Intrusive lava domes
Batholiths
Laccoliths
Phacoliths
Lopoliths
Sills
Dikes etc

25. Landforms produced during volcanic activities
Reference: www.usgs.gov.us

26. Conclusion
A volcano is considered to be an open surface of the earth and it allows the hot
molten lava to flow from the surface. Volcanologists and Geologists conduct
research and recommend preventive measures. We must follow the preventive
measures to reduce danger to life. We need to understand about volcanoes,
types of volcanoes to reduce the negative impact of volcano eruptions and take
advantage of its benefits on people and environment. Because strong explosive
volcanic eruptions are known to have a pronounced impact on the climate it is
important to estimate the spatial-temporal patterns of volcanic forcing.

27. References
1. S.Savindra, Physical Geography. Edition-2009, PRAYAG PUSTAK
BHAWAN, 20-A University Road, Allahabad-211002, India.
PP 113-125.
2. www.wikipedia.org/wiki/volcano
3. www.photos volcanic a.com/pictureviewer
4. www.volcanoes.org.uk/
5. http://www.cotf.edu/ete/modules/volcanoes/vtypesvolcan.html.