Disaster risk reduct LESSON 4 AND 5.pptx

this is the lesson for disaster risk reduction

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 Disasters" Video Presentation