This power point presentation focuses on the different hazards being brought by volcanic eruptions. It describes what a volcano is, what are the different types of volcanoes and what are the hazards are being experienced once a volcano erupted. Additionally, it also presents the effects of the given hazards to people and all type of elements at- risk

1. VOLCANIC HAZARDS

2. Volcano
A volcano is a rupture in the crust of a planetary-
mass object, such as Earth, that allows hot lava,
volcanic ash, and gases to escape from a magma
chamber below the surface.
is a vent, hill or mountain from which hot and
molten rocks (lava), rock fragments, and
gaseous materials have been ejected

3. Classification of Volcanoes
Volcanoes are classified based on how often they erupted
Active volcano erupted within the last 10,000 years.
Examples of active volcanoes in the Philippines are Mt.
Mayon, Mt. Pinatubo, and Mt. Bulusan.
Dormant or an inactive volcano, on other hand, did not
erupt for the past 10,000 years, but could erupt again
Extinct volcano have not erupted in the past 10,000
years and will not erupt again

4. Classification of Volcanoes
Another way volcanoes can be classified is based on its
shape or form, and composition.
Shield volcanoes are low,
broad, and slightly domed
volcanoes that are produced
by accumulated/solidified
fluid basaltic lava flows.
Volcanoes with this type are
Mauna Loa, which is the
world’s largest volcano, and
Kilauea in Hawaii

5. Composite volcanoes or
stratovolcanoes are the most
common type of volcanoes
famous for its conical shape.
This type of volcano is composed
of pyroclastic deposits and lava,
and is characterized to have
steep slopes with nearly
symmetrical structure. Mt.
Mayon in Albay, Philippines and
Mt. Fuji in Japan are famous
stratovolcanoes.
Classification of Volcanoes

6. Cinder cone volcanoes are the
simplest type of volcanoes.
These volcanoes are smaller
compared to others with a
height between 30 meters and
300 meters, and rarely
surpasses a height of 700
meters. Cinder cones also have
steep slopes with an angle
between 30 and 40 degrees. Mt.
Paricutin in Mexico and Smith
Volcano in Babuyan Islands are
examples of cinder cones
Classification of Volcanoes

7. VOLCANIC HAZARDS

8. What are the various volcano-related hazards?
Lahars are specific kind of
mudflow made up of
volcanic debris.
Lahars are formed :
1. when small slope collapses
gather water on their way
down a volcano
2. Through rapid melting of
snow/ice during eruption
3. From heavy rainfall on loose
debris

9. What are the various volcano-related hazards?
Lahars are formed :
4. When a volcano erupts through a crater lake
5. When a crater lake drains because of overflow or wall
collapse.

10. What are the Destructive Characteristics of Lahars ?
1. Lahars move rapidly down valleys like rivers of concrete
2. Lahars can occur with or without a volcanic eruption
3. Lahars pick –up materials as they travel. Which can cause
damage to structures in their path
4. Lahars and excess sediment cause serious economic and
environmental damage to rover valleys and flood plains

11. What are the various volcano-related hazards?
Ash fall
-consist of fragments of
pulverized rock, minerals
and volcanic glass created
during volcanic eruption.
-refers to all explosive
eruption products (
measuring less than 2 mm
in diameter)

12. What are the devastating effects of ashfall?
1. Ashfall and volcanic ash clouds are hazard to aviation
2. Can pose significant disruption and damage to buildings,
transportation, water, power supply, communication
equipment, agriculture, and primary production leading to
potentially societal impacts and costs.
3. Can cause respiratory problems when inhaled. It can also
pose health problems to animals once ingested

13. What are the various volcano-related hazards?
Pyroclastic flow
- Contains high- density
mix of lava blocks,
pumice, ash and
volcanic gas.
- Consist of two parts: a
lower basal flow of
coarse fragments that
moves along the
ground and turbulent
cloud of ash that rises
above basal flow

14. What are the hazards of pyroclastic flow?
Pyroclastic flows move at a very high speed down
volcanic slopes. It can destroy houses and other
structures, forests and farmlands, and can cause
fatalities and serious injuries to people and
animals.
Pyroclastic flows have extreme temperatures
ranging between 200 and 700 degrees Celsius. It
can travel at an average speed of 80 km/h.
Pyroclastic flow can also melt and mix with snow
and ice generating secondary hazards such as
flooding and lahars.

15. What are the various volcano-related hazards?
Volcanic gases
- gases that are released to
the atmosphere during
eruptions. Volcanic gases
include water vapor,
carbon dioxide, carbon
monoxide, sulfur dioxide,
hydrogen sulfide, hydrogen
chloride and hydrogen
fluoride.

16. What are the harmful effects of volcanic gases?
1. Carbon dioxide trapped in low – lying areas can
be lethal to people and animals
2. Sulfur dioxide is irritating to the eyes, skin and
respiratory system
3. Hydrogen sulfide is very toxic in high
concentrations
4. Hydrogen halides are strong, toxic acids

17. What are the various volcano-related hazards?
Lava flows
- Steams of molten
rock that pour or ooze
from an erupting vent.
- are rivers of
incandescent molten rock
or lava that erupted from
a crater or fissure and
moves downslope or
away from an eruption
vent .

18. The speed of lava flows;
A. Steepness of the slope of the ground where it
travels
B. The type of lava and its viscosity
C. Whether the lava flows in a restricted
channel, down a lava tube or as a broad sheet
D. Lava production rate at the vent.

19. What are the devastating effects of lava flows?
1. may cause other types of hazard
2. Everything in the path of an advancing lava flow will be
knock over, surrounded, buried or ignited by extremely hot
temperature of lava
3. When lava erupts beneath a glacier or flows over snow or
ice, melted water from ice or snow can result to lahar

20. What are the devastating effects of lava flows?
5. Methane gas, produced as lava buries vegetation, can
migrate in subsurface voids and explode when heated
6. Thick viscous lava flows, especially those that build a
dome, can collapse to form fast – moving pyroclastics
4. If it enters a body of water or water enters the lava
tube, the water will boil violently and cause an
explosive shower of molten spatter over wide area

21. What are the various volcano-related hazards?
Ballistic projectiles
-are volcanic rocks directly
ejected from the vent with
force and trajectory. These
rocks can vary, which can be
as small as an ash, or as a
boulder. These rocks can
travel from 2 to 5 km from
the vent

22. Signs of impending Volcanic Eruption
1. Intensified steaming activity with a change
of color from white steam to gray, or to dark
steam
2. Dried - up vegetation, streams and water
wells
3. Ground movement or tremors due to
volcanic earthquakes
4. Crater glow at or near the crater or
summit area

23. Signs of impending Volcanic Eruption
5. Increased frequency of landslides and
rockfalls
6. Increased temperature in hot springs and
crater lakes near the volcano
7. Residents near the volcano can hear
rumbling sound and can smell sulfur
8. Sulfur dioxide and other gas emissions

24. Activity
1. Using the map of the Philippines, identify the areas
where active, dormant and extinct volcanoes can
be found. Put a dot mark or a triangle on these
areas. (use different colors)
2. Answer the following questions:
- What are the areas where there are active
volcanoes?
- What 5 importance of knowing where these active
volcanoes are.