Chapter 4 Natural Hazards, Mitigation and Adaptation.pptx

Natural Hazards, Mitigation and Adaptation

1. Chapter 4: Natural Hazards, Mitigation and adaptation

2. Have you ever experienced a natural hazard in your community? What happened and how did people react ? Activity: Hazard Hunt

3. What hazard do you see ?

4. What do you think are the possible effects of this hazard on people, animals, and the environment ?

5. Natural hazards are events in nature that can cause great harm to people and the environment. Today, we will learn more about the types of natural hazards, why they happen, and how we can prepare for them

6. At the end of the lesson, the student should be able to: Describe the various hazards caused by earthquakes, volcanic eruptions and landslides Using hazard maps, identify areas prone to hazards brought about by earthquakes, volcanic eruptions, and landslides. Suggest practical ways of coping with hazards caused by earthquakes, volcanic eruptions, and landslides. Identify human activities that speed up or trigger landslides. Identify ways to lessen the occurrence of landslides in a landslide-prone community. Lesson Objectives

7. Geological Processes Where do geologic hazards usually occur? Geological hazard occur more frequently at areas where there are fault lines, volcanoes and steep slopes. Since the surface of Earth is made up of lithospheric plates that are moving on top of the asthenosphere. These movements along the different kinds of plate boundaries are the cause of the natural geologic phenomena such as earthquakes and volcanic eruptions.

8. Earthquakes An earthquake is the minimal to rapid shaking of the ground due to the movement of rocks along fractures, known as faults , on Earth's surface. These faults are usually associated with the parallel movement of plates in a transform fault. As the plates move rock deformation occurs and energy starts to build up. When the rocks break, energy released, resulting in an earthquake

9. Philippines is prone to earthquakes because of the numerous faults within the country. Note: Earthquakes most likely occur at fault lines and trenches.

10. Earthquake hazard Surface rupture and Physical damage Liquefaction Fires Tsunami Landslides

11. Surface rupture and physical damage is the most obvious hazard of an earthquake Earthquakes with higher energy create stronger ground motion, which can cause ground to ground to break and buildings to collapse. Urban areas would experience more of this damage due to the presence of more infrastructures. Surface rupture and Physical damage

12. Liquefaction occurs in areas where the soil becomes saturated with water. During an earthquake, the movement of the ground may loosen the soil and allow more water to seep in between the particles. This decreases the ability of the soil to support structures that are resting upon it. When it can no longer support a building, instead of being toppled over, the building starts to sink. Liquefaction mostly occur in reclaimed lands, which were once a part of a body of water. Liquefaction

13. Fires can break out during or after an earthquake due to damaged or broken utility lines, substations, and power plants. It can also occur when ground rupture breaks gas tanks or pipes that lead to gas leaks Fires

14. Tsunami or a harbor wave is an earthquake hazard that is generated when earthquakes occur on the seafloor. Tsunami displaces large volume of water from the sea to the land, causing damages in the cities and communities near the shore Tsunami

15. Landslide is another earthquake hazard that occurs when there is too much shaking of the ground. The movement loosens the soil, facilitating its downward movement. Landslide

16. Other factors that causes landslide Heavy rainfall Heavy rainfall saturates the land with water, thus, the stability of a slope and the friction between particles are lessened and cause the ground to flow Volcanic eruption Human Activities can cause earthquakes to loosen the materials that are located on a slope to move downward. . Population increase results in a greater need to build infrastructures, such as residential houses. An increase in urbanization creates more unplanned land-use and development. This increases the vulnerability of the land which are already prone to landslides. Other human activities that can trigger landslides are modification of slopes by construction of roads or buildings, deforestation, mining and quarrying activities, water management, and vibrations from heavy traffic.

17. To lessen the occurrence of landslide, one project by the government is using a Coconet Coconet is made of coconut fiber woven into nets that are biodegradable and has excellent water absorption and water-holding capacity. It is placed on the slopes to allow the vegetation to settle firmly in the soil, which helps soil conditioning and erosion control

18. The Philippines experiences a lot of earthquakes because it is located in the Circum -Pacific Belt, situated in the Pacific Ring of Fire. The two locations are the same but the term Pacific Ring of Fire is used in relation to volcanoes because of the molten rocks that are being ejected from them. The term is not in any way related to earthquakes. Did you know?

19. Questions How do plate movements cause earthquake? What are the causes of earthquake? How can you lessen the occurrence of landslide? How can you prepare for a landslide?

20. Earthquakes are sometimes used in predicting volcanic eruptions. An earthquake alerts the authorities to observe a nearby volcano. When a volcano shows signs of eruption, evacuation of the nearby villages should be immediately implemented. Volcanic eruptions

21. Pacific Ring of Fire is a region in the Pacific where most active volcanoes are located

22. Explosive eruptions - have magma that is highly viscous and contains large amounts of dissolved gases Two Types of Volcanic Eruptions

23. 2. Hawaiian type or non-explosive eruptions What is viscosity? It determines the ability of magma to flow. The lower the viscosity, the easier it is for the magma to flow. This viscosity of the magma is affected by silica content and temperature. Low-temperature magma with high silica content are highly viscous; high-temperature magma with low silica content has low viscosity. have magma that has low viscosity and low amount of dissolved gases

24. Explosive volcanic Eruptions release pyroclastic floes and materials that are considered to pose the greatest threat. Volcanic Eruption Hazards The pyroclastic flows often render people in a shock state since they become overwhelmed with what they are seeing . Too much pyroclastic material (e.g., tephra), may bury people and severely damage the agricultural land and livestock. Damaged agricultural land could lead to famine.

25. After an eruption, pyroclastic materials that have settled along the slope of the volcano get mixed with rainwater. This would start a mudflow or lahar moving at high speed, destroying everything along its path. Poisonous gases are also released by volcanoes. These gases can be lethal to people, animals, and plants. Just like earthquakes, violent volcanic eruptions may also happen underwater, which can trigger a tsunami.

26. Questions Why are earthquakes useful in predicting volcanic eruptions? How is lahar formed?

27. Hydro meteorological Phenomena

28. At the end of the lesson, the student should be able to: Describe the various hazards caused by hydro meteorological phenomena. Using hazards maps, identify areas prone to hydro meteorological hazards. Suggest practical ways of coping with hazards caused by hydro meteorological phenomena. Lesson Objectives

29. What are the different weather phenomena that are experienced in the Philippines? Tropical Cyclones Monsoons Thunderstorms

30. Monsoons are regional wind systems that are seasonally reversing. The mechanism of these monsoons is similar to how the local winds (sea breeze and land breeze) are generated. Thus, the reversal is attributed to the different amounts of energy received by the landmass during summer or winter. This phenomenon is most evident in Asia, since it has the largest landmass among the other continents. Monsoons

31. Summer and Winter Monsoons

32. Tropical cyclones are cyclones that are formed over warm oceans. The cyclones that form over the Pacific or Indian Ocean are called typhoons while cyclones that form over the Atlantic Ocean are called hurricanes . Tropical Cyclones

33. Thunderstorms are characterized by strong winds, heavy rain, lightning, and thunder. They are formed when a warm air mass is forced to move upward by a cold air mass, producing cumulonimbus clouds. As the clouds grow bigger, electrical charges start to form and static electricity is discharged in the form of lightning. When the lightning passes, it rapidly heats the air around it, causing the air to expand explosively and is heard as thunder. Thunderstorms

34. 1. Storm surge is the most destructive hydro-meteorological hazard. It is the rise of the normal sea level caused by the winds that are directed towards the shore. It can reach a height of at least 8 m and may cause the most destruction in coastal areas. Hydro meteorological Hazards

35. Wind damage is the most obvious hazard of cyclones and thunderstorms, since these are characterized by strong winds. It can cause severe damage to infrastructures that are weak and poorly built, although well-built structures may still be damaged by strong winds that create huge storm surges. Strong winds may also send debris from damaged infrastructure flying at high speeds, which could be dangerous. Prior to a strong typhoon, trim largely-grown trees and secure parts of the house that may be damaged or flown away by strong winds. During typhoons with strong winds, it is advisable to stay away from windows in case they break or shatter. Wind Damage

36. Flood is the hazard brought about by accompanied by strong winds, but continuous rainfall combined with the failure of the flood control system may be the cause of most of the casualties sustained by an area. Flood

37. Questions Why do some communities suffer greater damage from a typhoon than others, even if both are hit by the same storm? If you were a local leader, how would you balance economic activities (like farming or building businesses) with the risks of floods in flood-prone areas ?

38. Short Quiz: 1. Which of the following is NOT a hydro-meteorological phenomenon? a. Typhoon b. Flood c. Earthquake d. Monsoon

39. 2. What makes tropical cyclones and monsoons different from each other? a. Cyclones are long-term weather patterns, while monsoons are short-lived storms b. Cyclones form over oceans, while monsoons are seasonal wind patterns bringing rain c. Cyclones are only weak winds, while monsoons are destructive storms d. Cyclones occur only in the Philippines, while monsoons occur worldwide

40. 3. Which is a common effect of thunderstorms? a. Long periods of drought b. Lightning, strong winds, and heavy rains c. Melting of glaciers d. Large ocean waves caused by earthquakes

41. 4. Which of the following best describes a tropical cyclone ? a. A rotating system of strong winds and heavy rains formed over warm oceans b. A sudden shaking of the ground caused by tectonic movements c. A period of little or no rainfall over a long time d. A column of air rotating violently on land.

42. 5. A storm surge is best described as: a. Sudden rise of seawater due to strong winds and low pressure b. Overflowing of rivers due to melting ice c. Sudden heavy rainfall d. Large inland wave caused by an earthquake

43. Assignment: Locate the place where you live and determine the estimated height of flood in your area using a hazard map.

44. Marine and Coastal Processes

45. At the end of the lesson, the student should be able to: Describe the coastal processes that lead in coastal erosion, submersion, and saltwater intrusion. Identify critical areas in a community that is prone to coastal erosion, submersion, and saltwater intrusion Suggest practical ways of coping with coastal erosion, submersion, and saltwater intrusion Lesson Objectives

46. What are the hazards that usually occur along marine and coastal areas? Coastal processes, such as waves, tides, sea level changes, crustal movement, and storm surges will result to coastal erosion, submersion, and saltwater intrusion.

47. Coastal erosion is the wearing down of the coastlines by the movement of wind and water. It is not a constant process; instead, the rate of erosion depends on other events such as cyclones. When cyclones occur along coastal areas, the winds and waves carry the sediment away from the shoreline. . 1. Coastal Erosion

48. Shorelines play an important role to society. They are used in transportation, fishing, and tourism. Therefore, preventing coastal erosion is of utmost priority Shorelines

49. 1. Hard stabilization is done by building structures that will slow down the erosion on areas that are prone to erosion. Examples of hard stabilization structures are jetties, sea walls, and breakwaters. Though they may slow down the erosion in one area, it may hasten the erosion in other areas. 2. Soft stabilization includes the process of beach nourishment, wherein sand from an offshore location is brought to an area with a receding shoreline. It does not make use of structures like the ones used in hard stabilization. 3. Retreat is the option taken by residents near areas where coastal erosion is already severe. At this point, the authorities no longer attempt to save the shoreline but rather limit the amount of human interference in the area. There are three main classifications of stabilizing the shoreline

50. Submersion happens because of the changes in the sea level, specifically, when it rises dangerously above the normal level. This is all due to the increase in the global temperature, which, in turn, melts the glacial deposits and increases the overall sea level. Another factor that may cause submersion is the vertical movement of the plates. Landmasses can be uplifted, which can also cause changes in the sea level. It can also be caused by tsunamis and storm surges. 2. Submersion

51. In coastal areas where there is an interaction between saltwater and fresh water, saltwater intrusion is one of the hazards that are evident in that area. Saltwater intrusion is the movement of saltwater into the freshwater aquifer. The natural flow is that the fresh water, which is less dense, moves towards the denser saltwater. But if the fresh water is being withdrawn faster than it is being replenished, then there will be a change in pressure and saltwater intrusion will occur . 3 . Saltwater Intrusion

52. The well withdraws groundwater very fast, and is replaced by saltwater due to pressure differences. If it continues, the well will be filled with saltwater rather than fresh water.

53. S top using the well where fresh water has been depleted and let the groundwater replenish naturally via the water cycle . T o build two wells: a pumping well built farther inland and an injection well built closer to the coast. Using the injection well, fresh water is pumped into the aquifer to prevent the saltwater from intruding. Ways of preventing saltwater intrusion

54. Question: 1. Mangrove forests protect coastal areas from storm surges and erosion, yet many are cut down for fishponds or resorts. If you were a community leader, how would you balance economic benefits with environmental protection ? 2. With climate change causing sea levels to rise, some islands may eventually disappear. Should governments invest in expensive coastal defenses (like seawalls) or prioritize relocating communities? Why?

55. Mitigation and Adaptation

56. At the end of the lesson, the student should be able to: Suggest ways to prevent or mitigate the impact of land development, waste disposal, and construction of structures on coastal processes. Advocate the use of structures that mitigate the effects of coastal processes. Perform actions that should be done before, during, and after earthquakes, landslides, volcanic eruptions, and typhoons. Lesson Objectives

57. Example of Landslide and Flood hazard Map The susceptibility map of Quezon City provides information on which areas are at risk for landslide and Flooding

58. In preparation for natural hazards, information regarding what to do before, during, and after a natural hazard is disseminated all over the country. The following are the things to do to be prepared for each natural hazard

59. Instructions : 1. Form 3 Groups Group 1: Geological Hazards ( earthquake and volcanic eruption) Group 2: Hydrometeorological Hazards (typhoon, flood, storm surge, Wind damage) Group 3: Marine & Coastal Hazards (coastal erosion, submersion, Saltwater Intrusion) 2. Task Each group will prepare a Hazard Action Plan Poster that contains: Hazard Description (What is the hazard? What damages can it cause?) Mitigation Strategies (What should be done before the hazard to lessen risks?) Adaptation Strategies (What should be done during & after the hazard to survive and recover?) Community Role (What can families, schools, and LGUs do?) 3. Presentation Each group presents their poster in front of the class. Group Activity : Plan, Adapt, and Protect

60. Criteria Excellent (10) Good (8) Fair (6) Needs Improvement (4 Content Accuracy Information is complete, accurate, and shows deep understanding of hazard, mitigation, and adaptation. Information is mostly accurate, with minor errors or missing details. Information is somewhat unclear; key ideas are missing. Many inaccuracies; lacks understanding of hazards. Creativity & Organization Poster is very creative, well-organized, and easy to understand. Poster is organized and understandable, with some creativity. Poster is somewhat organized but hard to follow. Poster is messy, unclear, or lacks creativity. Application of Strategies Mitigation & adaptation strategies are specific, realistic, and community-based. Strategies are realistic but not very detailed. Strategies are too general or impractical. Strategies are missing or irrelevant. Group Collaboration All members clearly contributed; strong teamwork shown. Most members contributed; teamwork was evident. Few members contributed; uneven participation. No collaboration; work done by 1–2 members only. Presentation Skills Clear, confident, engaging; answers questions effectively. Clear and understandable; minor issues in delivery Difficult to hear/understand; minimal engagement. Poor presentation; very unclear or unprepared. Rubric for Grading