Disaster Readiness and Risk Reduction Management
WEEK 7
Volcano Hazards
Learning Outcomes
At the end of the lesson, the student should be able to:
Identify the most common volcano-related hazards in the
Philippines;
Explain the differences of the various volcano-related hazards;
Identify signs of impending volcanic eruptions;
Explain different signs of volcanic eruption;
Identify appropriate measures before, during, and after
volcanic eruption;
Digital Communication and Technological College Inc.
Disaster Readiness and Risk Reduction Management
Prepared by: Ms. Julie May V. Profugo,LPT 1
DIFFERENT TYPES OF VOLCANIC HAZARDS
Ballistic Projectiles
- Ballistic Projectiles are volcanic materials which are directly ejected from the
volcano's vent with force and trajectory. These objects endanger life and property
due to the force of impact of falling fragments, but this occurs only close to an
eruption vent.
Ash Fall
- Volcanic Ash Fall–A "Hard Rain" of Abrasive Particles. Volcanic ash consists of tiny
jagged particles of rock and natural glass blasted into the air by a volcano.
Pyroclastic Flow
- Pyroclastic flows contain a high-density mix of hot lava blocks, pumice, ash and
volcanic gas. They move at very high speed down volcanic slopes, typically following
valleys.
Lava Flows
- Lava flows are masses of molten rock that pour into the Earth's surface during an
effusive eruption
Volcanic gases
- Volcanic gases are gases given off by active (or, at times, by dormant) volcanoes.
These include gases trapped in cavities (vesicles) in volcanic rocks, dissolved or
dissociated gases in magma and lava, or gases emanating directly from lava or
indirectly through ground water heated by volcanic eruption.
Debris Avalanche or volcanic landslide
- Massive collapse of a volcano, usually triggered by an earthquake or volcanic
eruption
Lahar flow
- Lahar is a wet mass of volcanic fragments flowing rapidly downhill. Usually contain
ash, breccia, and boulders mixed with rainwater or with river or lake water displaced
by the lava flow associated with the volcano
Tsunami
- Tsunami are big sea waves or waves trains that are generated by sudden
displacement of water (could be generated during under sea eruption or debris
avalanche).
SIGNS OF VOLCANIC ERUPTION
In 2005 USGS geologist Chris Newhall made a list of the six most important signs of an
imminent volcanic eruption. They are as follows:
Digital Communication and Technological College Inc.
Disaster Readiness and Risk Reduction Management
Prepared by: Ms. Julie May V. Profugo,LPT 2
1. Gas leaks — the release of gases (mostly H2O, CO2, and SO2) from the magma into
the atmosphere through cracks in the overlying rock
2. Bit of a bulge — the deformation of part of the volcano, indicating that a magma
chamber at depth is swelling or becoming more pressurized
3. Getting shaky — many (hundreds to thousands) of small earthquakes, indicating that
magma is on the move. The quakes may be the result of the magma forcing the
surrounding rocks to crack, or a harmonic vibration that is evidence of magmatic fluids
moving underground.
4. Dropping fast — a sudden decrease in the rate of seismicity, which may indicate that
magma has stalled, which could mean that something is about to give way
5. Big bump — a pronounced bulge on the side of the volcano (like the one at Mt. St.
Helens in 1980), which may indicate that magma has moved close to surface
6. Blowing off steam — steam eruptions (a.k.a. phreatic eruptions) that happen when
magma near the surface heats groundwater to the boiling point. The water eventually
explodes, sending fragments of the overlying rock far into the air.
VOLCANO HAZARD MAP
Typically, a number of types of hazards will result from a volcanic eruption. Each
hazard poses different risks affecting different areas.
Depending on where you are some of the most threatening hazards include
pyroclastic falls, pyroclastic flows and surges, lava extrusions (flows and domes), lahars,
debris avalanches and volcanic gases.
To help you understand the areas that may be affected hazard maps are used.
These show areas that can be impacted and where it is safe.
Digital Communication and Technological College Inc.
Disaster Readiness and Risk Reduction Management
Prepared by: Ms. Julie May V. Profugo,LPT 3
Volcanic eruption greatly affects the lives of people and their properties. For this reason, it is
important for you to know the appropriate measures or actions you need to do before,
during, and after such phenomena.
PRECAUTIONARY AND SAFETY MEASURES FOR VOLCANIC ERUPTIONS
Before Volcanic Eruption
Assist in community efforts such as constructing diversion ditches and placing sand
bag baffles in possible lava or lahar pathways.
Clear all debris and other flammable materials in the premises and nearby areas.
Try to store water in containers for fire-fighting purposes. The explosion carrying
burning stones and the lava flow could trigger fire in your vicinity.
If possible, temporarily dismantle the storm water gutter in your roofs to allow the free
flow of ash from the eruption. Reinforce the weak parts of your house.
Digital Communication and Technological College Inc.
Disaster Readiness and Risk Reduction Management
Prepared by: Ms. Julie May V. Profugo,LPT 4
Plan your escape route in case there would be need to evacuate your family.
If you have a motor vehicle, (land vehicle or banca), fill it with gas and have it
conditioned to be used in these eventualities.
Stock enough non-perishable food and potable water for the family.
Remove breakable materials in high places such as light bulbs, chandelier,
wall and ceiling decorations, contents of shelves and cabinets and place them
on the floor. The earth movement may break them and hurt the house
occupants.
During Volcanic Eruption
If you are caught on the road or become stranded, do not panic. Execute the other
evacuation plan that your family has decided.
Do not go sightseeing. Stay inside the house/building/evacuation center.
Your presence outside may-hamper the flow of evacuation traffic or you may get hurt
by the effects of the explosion or earthquake.
Take cover under a table similar strong structure and stay-away from glass windows
and appliances.
Do not try to clean or shovel the ashfall during the eruptions. Ash may hamper your
visibility or quakes may throw you down or lightning may strike you.
Damaged properties could be repaired but not the lives lost.
Wear gas mask or cover your face with clean wet towel or cloth to prevent ash from
irritating the eyes and entering the respiratory tract.
After Volcanic Eruption
Digital Communication and Technological College Inc.
Disaster Readiness and Risk Reduction Management
Prepared by: Ms. Julie May V. Profugo,LPT 5
Listen to the latest radio updates and the alert signals. Listen to relevant advice from
authorities. Stay in the house/building/evacuation center until the volcanic eruption
and after shocks have subsided.
Survey with caution the damage from the volcanic impact with caution. Look out for
road erosions, landslides, flooded areas, fallen power lines and trees, weakened
structures, molten lava deposits, lahar mud flow movements. Children should not
roam the damaged area.
Temporarily confine them to the house/evacuation center. Residual effects of the
explosion could still be a threat to lives and properties.
Check sanitation facilities (water supply system, toilet, waste water drainage, dump
site). Due to the earth's movement, all water sources are declared unsafe for
drinking. Institute emergency treatment of drinking water (boiling, chlorination, etc.)
Construct temporary pit latrines. Cover the human waste with lime or ash or earth
after every defecation.
Do the same to your garbage pit. Drain stagnant water in the vicinity to prevent insect
infestation.
Cook food thoroughly and always observe personal hygiene. Avoid overcrowding in
the sleeping area. Request assistance from the health authorities for other health and
sanitation services that you would need.
Only the adult members of the family should be allowed to go home to inspect the
house condition.
The rest of the family should only return when it is safe. Otherwise, stay in the
evacuation center.
Be an active member in the maintenance of a peaceful and sanitary condition of the
camp site. Assist in the clearing of damaged facilities and in the rehabilitation of the
disaster area.
Week 7
Digital Communication and Technological College Inc.
Disaster Readiness and Risk Reduction Management
Prepared by: Ms. Julie May V. Profugo,LPT 6
Activity Sheet #1
VOLCANO HAZARDS
Student’s Name:_____________________________ Date:_____________________
Grade & Track: _____________________ Teacher: ______________
Think of words, situations or ideas that you can associate to the word hazard.
Week 7
Activity Sheet #2
Digital Communication and Technological College Inc.
Disaster Readiness and Risk Reduction Management
Prepared by: Ms. Julie May V. Profugo,LPT 7
VOLCANO HAZARDS
Student’s Name:_____________________________ Date:_____________________
Grade & Track: _____________________ Teacher: ______________
Read each item comprehensively. Then choose the letter of the correct answer.
1. Which of the following signs of an impending volcanic eruption refers to the decrease
of pressure and escape of gases as magma gets near the surface of the volcano?
A. Bulges in the mountain/inflammation
B. Increase in number of earthquake
C. Harmonic Tremors
D. Gas emission
2. How do you call the masses of molten rock that pour into the earth’s surface during
an effusive eruption?
A. Ballistic Projectiles
B. Volcanic Gases
C. Lava Flow
D. Ash Fall
3. Which of the following is NOT an important part of an emergency supply kit?
A. Flashlight
B. Batteries
C. Water
D. Video Games
4. What is one of the most important actions to take before a volcanic eruption?
A. Cover your garden with soil
B. Go near the volcano to take pictures.
C. Keep goggles and a dust mask handy
D. Read about volcanic eruptions in text book.
5. Based on the lava flow hazard map of Mayon volcano above, how many kilometres
from the crater is considered prone to lava flow?
A. 4 B. 6 C. 7 D. 8
Week 7
Activity Sheet #3
Digital Communication and Technological College Inc.
Disaster Readiness and Risk Reduction Management
Prepared by: Ms. Julie May V. Profugo,LPT 8
VOLCANO HAZARDS
Student’s Name:_____________________________ Date:_____________________
Grade & Track: _____________________ Teacher: ______________
Make a poster and a slogan that gives warning to people about an approaching volcanic
eruption.
USE SEPARATE SHEET OF
PAPER FOR YOUR DRAWING
WRITE YOUR SLOGAN HERE
Digital Communication and Technological College Inc.
Disaster Readiness and Risk Reduction Management
Prepared by: Ms. Julie May V. Profugo,LPT 9
