Volcanoes form when molten rock and hot gases erupt from openings in the earth's crust. There are three main types of volcanoes defined by their shape: composite/stratovolcanoes which are tall mountains formed from layers of erupted material; cinder cones which are small, steep-sided hills formed from explosive eruptions of rock fragments and ash; and shield volcanoes which have broad dome shapes formed by low-viscosity lava. Volcanoes can be classified as active if they have erupted within the past 10,000 years, inactive if they have not erupted in that time frame, or potentially active if they show signs of activity but have not recently erupted.

2. VOLCANOES

3. OBJECTIVES:
1. Describe the different types of volcanoes.
2. Differentiate active and inactive volcanoes.

4. What is volcano?
Volcano is a natural
opening in the surface of the
earth where molten rocks, hot
gases, smoke, and ash are
ejected.

5. Parts of an erupted volcano
magma chamber
conduit
main crater /vent
ashes, smoke & gas
exploded rocks
side vent
side vent
lava
lava
crust
crust

6. Types of Volcanoes

7. Shape of Volcanic Cone
Composite/Stratovolcano Cinder cone Shield
tall mountains made of lava,
pyroclastic deposits or strata
(layers) from explosive
eruptions. It is the most common
and abundant volcano in Pacific
Ring of Fire.
Formed by ejected lava
fragments or igneous
rocks called cinders.
The most abundant type
of volcano. Explosion of
rocks and lava.
Formed by non/low/less
viscous or free-flow or
very fluid lava that form
dome structure like
soldiers shield.

8. Record of Eruption
Inactive
Volcano
Active
Volcano

9. Record of Eruption
Inactive
Volcano
Did NOT ERUPT within
600 years to 10,000
years. The physical form
of volcano is changed by
EROSION and
WEATHERING and
FORM DEEP and LONG
GULLIES.

10. Record of Eruption
Has a record of
eruption within
600-10,000
years.
Active
Volcano

11. Potentially Active
Volcano
- are volcanoes that have the appearance
of a young volcano. It has actions and signs of an
active volcano but there is no eruption recorded. For
example, Mt. Apo. Mt. Apo has ashes or smoke
release but it does not came from magma or lava
but sulfur.

12. PACIFIC RING OF FIRE

13. Types of Volcanic Eruption

14. Phreatic

15. Phreatic Eruption
is a steam-driven eruption where
rocks boils the water. Only rocks touches
the water. Shown by white steam or white
column of ash.

16. Phreatomagmatic

17. Phreatomagmatic Eruption
is a violent eruption due to contact
of magma and water. This time, the
magma touches the water. As a result, a
large column of black ash and high speed
pyroclastic density called base surge.

18. Strombolian

19. Strombolian Eruption
is an eruption that start from
weak to violent eruption
characterized by lava fountain.

20. How can a volcano create lightning?
Volcanic lightning is an
electrical discharge caused by a
volcanic eruption. So, the ash
from the volcano and the air of
the atmosphere are colliding to
each other creating an electric
charge. The positive and
negative charges separate from
one another. As they separate
away from each other, the
result is a spectacular
discharge of lightning.

21. Vulcanian

22. Vulcanian Eruption
is an eruption that characterized
by tall eruption columns that reach up
to 20 km high with pyroclastic flow and
ashflow tephra.

23. Plinian

24. Plinian Eruption
excessively explosive type of
eruption of gas and pyroclastics.