The document outlines various earthquake and volcanic hazards, detailing their effects, how they occur, and strategies for mitigation. Key earthquake hazards include ground shaking, surface rupture, liquefaction, landslides, and tsunamis, while volcanic hazards include lava flows, pyroclastic flows, ash fall, volcanic gases, and lahars. Understanding and preparing for these hazards through monitoring, evacuation plans, and community education is essential for minimizing risks and protecting lives.

1. LESSON 4:
POSSIBLE EARTHQUAKE HAZARDS

2. INTRODUCTION
Earthquakes are unpredictable natural disasters that can
cause significant destruction. While ground shaking is
the most recognized effect, earthquakes can also trigger
secondary hazards, such as tsunamis and landslides,
which pose additional risks to affected areas. This lesson
discusses various hazards caused by earthquakes and
how they can be mitigated to reduce loss of life and
damage to property.

3. Ground Shaking
• Ground shaking occurs due to the movement of seismic
waves during an earthquake. The severity of shaking is
determined by factors like the earthquake’s magnitude,
distance from the epicenter, and local geology.
– Effects: Buildings and infrastructure may collapse, leading to
injuries, fatalities, and disruptions in essential services.
– Mitigation: Designing earthquake-resistant buildings and
enforcing stringent building codes help reduce the damage
caused by ground shaking.

4. Ground Shaking

5. Ground/Surface Rupture
• Ground or Surface rupture occurs when the ground on opposite
sides of a fault moves during an earthquake, causing visible
displacement on the Earth's surface. This movement can occur
horizontally, vertically, or in a combination of both, depending on the
type of fault.
– Effects: Surface rupture can severely damage structures built directly on
fault lines. Roads, pipelines, and railways may be torn apart by the
displacement, leading to interruptions in transportation and water supply
systems.
– Mitigation: Avoiding construction on or near fault lines is key to minimizing
damage. Zoning laws and land-use planning can prevent development in
high-risk areas.

6. Ground/Surface Rupture

7. Liquefaction
• Liquefaction happens when saturated, loose, sandy soils lose
their strength and stiffness due to the intense shaking from an
earthquake. This causes the ground to behave like a liquid
rather than a solid, leading to ground failure.
– Effects: Liquefaction can cause buildings to tilt or sink, roads to crack,
and underground pipes to burst. Low-lying areas, especially near
rivers or coastal zones, are particularly susceptible.
– Mitigation: Soil improvement techniques, such as compaction or
drainage, can help reduce the likelihood of liquefaction. Building on
stable ground or designing foundations to withstand liquefaction is
also important.

8. Landslides

9. Earthquake – induced landslides
• Earthquake-induced landslides occur when the shaking from
an earthquake destabilizes loose rock, soil, or debris on a
slope, causing it to slide downhill.
– Impact: Landslides can bury entire villages or communities, block
roads, and disrupt transportation and communication lines. They
also pose a risk to rescue operations in the aftermath of an
earthquake.
– Mitigation: Slope stabilization methods, including the use of
vegetation to bind the soil, and constructing retaining walls can help
prevent landslides. Identifying areas prone to landslides through
geotechnical surveys and avoiding construction in these areas are
also key strategies.

10. Earthquake – induced landslides

11. Earthquake – induced landslides
• The following triggers may create conditions in an area
that make it prone to landslides;
– Steep slopes – increase the potential energy of the
impending landslides.
– Weakening of slope material – unstable landmass;
– Weathering of rocks – alterations of rock condition and
composition over time; and
– Overloading on the slope – may be brought about by the
man – made development.

12. Tsunamis
• Tsunamis are large sea waves generated by underwater
earthquakes, especially those with a magnitude of 7.0 or higher.
When the seabed shifts during an earthquake, it displaces large
volumes of water, resulting in waves that can travel great
distances across oceans.
– Effects: Tsunamis can inundate coastal areas, destroying homes,
infrastructure, and ecosystems. They also pose a high risk of drowning
and injuries to people living near the coast.
– Mitigation: Coastal communities can reduce tsunami risk by creating
early warning systems, developing evacuation plans, and building
protective barriers. In some areas, planting mangroves or creating
artificial reefs can help reduce the impact of waves.

13. Tsunamis

14. Conclusion
• Earthquakes bring with them multiple hazards, including
ground shaking, surface rupture, liquefaction, landslides, and
tsunamis. Each of these hazards has its unique challenges and
requires specific mitigation measures. Understanding the
potential risks and preparing for them through structural
engineering, early warning systems, and public education is
essential in minimizing the damage and loss of life during an
earthquake. By integrating knowledge of these hazards into
disaster preparedness plans, communities can build
resilience against earthquakes and their aftereffects.

15. Activity
• Answer LEARNING ENHANCEMENT WORKSHEET (pg.
93) on your book. Multiple choice 1 to 13.

16. Lesson 5: Volcanic Hazards

17. Introduction:
• Volcanoes are natural features that can be both awe-
inspiring and dangerous. They form when molten rock
(magma) from beneath the Earth's surface erupts,
often violently. While volcanic eruptions can create
new land and have beneficial effects, they also pose
significant hazards to humans and the environment.
Understanding volcano hazards is critical for reducing
risks and protecting communities.

18. Introduction:
• Volcano Hazards Overview:
• Volcano hazards can be classified into primary and
secondary hazards:
• Primary Hazards: Directly caused by volcanic activity.
• Secondary Hazards: Indirect hazards resulting from
volcanic activity.

19. Primary Volcanic hazards
– Lava Flows: Molten rock that pours from a volcano during
an eruption. Lava flows can destroy buildings, roads, and
vegetation, but they move slowly enough for people to
evacuate.
– Pyroclastic Flows: Fast-moving currents of hot gas and
volcanic matter that can travel down the slopes of a volcano
at high speeds. Pyroclastic flows are extremely dangerous
due to their speed and high temperatures, which can
destroy anything in their path.

20. Primary Volcanic hazards

21. Primary Volcanic hazards
• Ash fall: Volcanic ash consists of tiny rock particles
ejected during an eruption. It can cause respiratory
issues, contaminate water supplies, damage
machinery, and collapse roofs under its weight.

22. Primary Volcanic hazards
• Volcanic Gas: Volcanic eruptions release gases such as
carbon dioxide, sulfur dioxide, and hydrogen sulfide.
These gases can be harmful or even fatal to humans
and animals, and they can also contribute to
environmental issues like acid rain.

23. Secondary Volcanic hazards
• Lahars: Volcanic mudflows or debris flows caused by
the mixing of volcanic material with water (often from
heavy rains or melting ice). Lahars can bury
communities and cause massive destruction.

24. Secondary Volcanic hazards
• Landslides: Volcanic eruptions can trigger landslides,
particularly when the structure of the volcano
weakens.

25. Secondary Volcanic hazards
• Tsunamis: Underwater volcanic eruptions or volcanic
activity near coastal areas can displace large amounts
of water, leading to tsunamis.

26. Volcanic Hazards
• Volcano Monitoring and Risk Reduction:
– Scientists use a variety of tools and techniques to monitor
volcanoes and predict eruptions, such as:
• Seismographs: Measure earthquakes caused by the movement of
magma.
• Gas Monitoring: Detects changes in volcanic gas emissions that
may indicate an impending eruption.
• Satellite Imagery: Tracks changes in the surface temperature and
deformation of the ground around a volcano.
• Ground Deformation: GPS and other methods measure swelling or
sinking of the ground as magma moves beneath the surface.

27. Volcanic Hazards
• Risk reduction strategies include:
– Developing early warning systems.
– Creating hazard maps to identify danger zones.
– Educating the public about evacuation plans and volcano
preparedness.
– Enforcing land-use regulations to prevent building in high-
risk areas.

28. Volcanic Hazards
• Risk reduction strategies include:
– Developing early warning systems.
– Creating hazard maps to identify danger zones.
– Educating the public about evacuation plans and volcano
preparedness.
– Enforcing land-use regulations to prevent building in high-
risk areas.

29. Conclusion:
• Conclusion: Volcano hazards can be devastating, but
with proper monitoring, risk reduction measures, and
community preparedness, the impacts of volcanic
eruptions can be minimized. Understanding the nature
of these hazards and how they can affect the
environment and human activity is key to reducing
their risks.

30. Activity
• Answer LEARNING ENHANCEMENT WORKSHEET on
page 129 of your book. Multiple choice

31. Activity
• Answer LEARNING ENHANCEMENT WORKSHEET on
page 129 of your book. Multiple choice

32. Performance task Quarter 1
• Guidelines for the Activity: "Basic Tips in Times of Disas
ters" Video Presentation