Disaster Readiness and Risk Reduction
LESSON 2: Natural Hazards
Types of Natural Hazards
The Philippine Islands are prone to all kinds of natural hazards because of their geographical location and physical environment. The country is strategically located in the path of turbulent and destructive cyclones in the Pacifi c, and the “Ring of Fire”. This situation has adverse effects, not only on the lives and properties of the Filipino people, but also on the economy of the nation, as hazard impacts may result in widespread environmental and property damages. Natural hazards may cause danger to people, structures or economic assets, and may lead to a disaster if they are not mitigated against and prepared for.
Phenomena that are atmospheric, hydrometeorological or oceanographic and geographical in nature may cause the loss of life or injury, property damage, social and economic disruption and/or environmental degradation. Hydrometeorological and geographical hazards can be single, sequential or a combination in origin and effects. The common hazards associated with these are heavy rains, strong winds, storm surge, fl oods and landslides/ mud slide /mud fl ow.
Geological hazards are normal and their processes occur as irregular events with direct interaction with the environment. They are capable of causing signifi cant negative impact on human well-being. Their non-rhythmic occurrence makes their predictability diffi cult. An important characteristic of many geological hazards is their prime land preference – the characteristic of preferentially occupying areas targeted by man for his use. Almost all types of geological hazards occur in the Philippines except hazards associated with glaciers and seasonal snowfall. Hazards arising from volcanic eruptions, earthquakes and other related geotectonic phenomena such as landslide, tsunami and faulting are the most mitigated ones due to the frequency of their occurrence.
Hydro-Meteorological Phenomena and Hazard
Cyclone
A cyclone is an intense low pressure s y s t e m w h i c h i s characterized by strong spiral winds towards the center, called the “Eye” in a counter-clockwise fl ow in the northern hemisphere. Hazards due to tropical cyclones are strong winds with heavy rainfall that can cause widespread fl ooding/fl ashfl oods, storm surges, landslides and mudfl ows.
Classification
• Tropical Depression – maximum winds from 35 kph to 63 kph
• Tropical Storm – maximum winds from 64 kph to 118 kph
• Typhoons – maximum winds exceeding 118 kph
Typhoon
A typhoon is a large, powerful and violent tropical cyclone. It is a low pressure area rotating counterclockwise and containing rising warm air that forms over warm water in the Western Pacifi c Ocean. Less powerful tropical cyclones are called Tropical Depressions and Tropical Storms. A typhoon is called a hurricane in the Atlantic Ocean, a cyclone in the Indian Ocean and wily-wily in Australia. Typhoons can infl ict terrible damage due to thunderstorms, violent winds, torrential rain, fl oods, landslides, large and very big waves associated with storm surges. Hurricane-force winds can reach out as little as 40 km from the center of a small hurricane and as far as 240 km in a large hurricane. Tropical storm-force winds can extend as far as 480 km from the center of a large hurricane. These are very dangerous storms.
What to do before:
•Establish and maintain coordination with Barangay Disaster Coordinating Councils (BDCC).
•Ensure that the school building can withstand heavy rain and strong winds. Single level schools built at ground level may be anchored by guy wires to strengthen the stability of the structure.
• Learn about typhoon and other weather disturbances, their signs and warnings, effects and dangers and how to protect the school children, records and school property.
• Educate school children on preparedness for tropical cyclones. • Participate actively in the school’s disaster response – drill or simulation.
• Observe strictly Department policies on the suspension of classes or invoke school-based decisions in coordination with Local Government Units.
What to do during
• Monitor through radio or other reliable sources the latest offi cial report of PAGASA on the typhoon. • Gather the pupils in the most stable, strong and safe school building when it is no longer safe for them to go home.
• Advise pupils/students to stay indoors and away from windows.
• Coordinate with the proper school offi cials on possible immediate evacuation measures especially if the school is located in a low-lying area.
• Ensure that pupils/students will remain calm by keeping them informed of the latest developments.
What to do after
•Establish and maintain coordination with Barangay Disaster Coordinating Councils (BDCC).
•Ensure that the school building can withstand heavy rain and strong winds. Single level schools built at ground level may be anchored by guy wires to strengthen the stability of the structure.
• Learn about typhoon and other weather disturbances, their signs and warnings, effects and dangers and how to protect the school children, records and school property.
• Educate school children on preparedness for tropical cyclones. • Participate actively in the school’s disaster response – drill or simulation.
• Observe strictly Department policies on the suspension of classes or invoke school-based decisions in coordination with Local Government Units.
Geological Phenomena and Hazards
Earthquake
An earthquake is a shaking of the ground caused by sudden slippage of rock masses below or at the surface of the earth. It is a wavelike movement of the earth’s surface. An earthquake may be classifi ed as either tectonic or volcanic. In certain cases, earthquakes can result from man-made activities such as detonation of explosives, deep mining activities, etc. However, these earthquakes are mild and may be felt only as tremors. A very severe earthquake is usually associated with shocks called foreshocks and aftershocks. Foreshocks are a series of tremors that occur before the main earthquake. Aftershocks are weaker earthquakes that follow the main shocks and can cause further damage to weakened buildings. Be aware that some earthquakes are actually foreshocks, and a stronger earthquake might occur.
What to do before:
• Recommend to appropriate authorities the evaluation of structural soundness of school buildings and important infrastructures.
• Request appropriate authorities to determine whether the school site is along an active fault and/or in liquefaction or landslide prone areas which may cause school buildings to fall.
• Make sure that school building design complies with the National Building Code Standard.
• On existing school buildings with one door, request proper authorities to provide two exit doors for every classroom, both with swing-out direction. Geological Phenomena and Hazards natural hazards 2 natural hazards 2 34 Disaster Risk Reduction Resource Manual Disaster Risk Reduction Resource Manual 35
• Check for the presence of other potential sources of hazard due to secondary effect of earthquakes like steep hill slopes, hanging heavy objects, dams, storage tanks, falling debris, and fire.
• Strap heavy furniture/cabinets inside the classrooms to the wall to prevent sliding or toppling;
• Store breakable items, harmful chemicals and flammable materials inside the classrooms in the lowermost shelves and secure firmly.
• Install latches on drawers and cabinets.
• Check classrooms for hanging or unstable objects that may fall on the pupils/students during the earthquake.
•Familiarize pupils/students as well as school personnel with the easiest exit or evacuation route to take. Develop a School Earthquake Evacuation Plan and hang/post this in the corridor of each building.
What to do during
• Direct pupils/students to stay inside a structurally sound building. • Advise pupils/students to protect their body from falling debris by bracing themselves in a doorway or by getting under a sturdy desk or table.
• When inside a vehicle, pull to the side of the road and stop. Do not attempt to cross bridges or overpasses which may have been damaged.
• Direct pupils/students to move to an open area when they are outside a building or any structure.
• Stay away from power lines, posts, walls, and other structures that may fall or collapse. Stay away from buildings with large glass panes.
• Move away from steep escarpments which may be affected by landslides particularly if they are on a mountain or near steep hill slopes.
What to do after
• Advise pupils/students to take the fastest and safest way out if caught in an old or weak classroom building. They should be advised to : • Get out calmly and in an orderly manner. Not to rush or push one another.
• Not to use elevators, but instead use the stairs;
• Check themselves for cuts and for injuries and approach the nearest teacher for assistance.
• Check the surroundings of the schools
• Call the authority to clean up chemical spills, toxic and fl ammable materials since this is hazardous to untrained people.
• Check for fi re and if any, have it controlled.
• Check the water and electrical lines for defects. If any damage is suspected, turn the system off in the main valve or switch.
• Help reduce the number of casualties from the earthquake:
• Do not enter partially damaged school buildings, as strong aftershocks may cause these to collapse.
• Gather information and disaster prevention instructions from battery-operated radios.
• The School Head/Principal shall provide safety precautions. He/She shall not allow any student to go out of the school unless they are with their parents/relatives. Identify/List pupils/students fetched by parents/relatives and those left behind.
• Do not use the telephone to call relatives and friends. Disaster prevention authorities may need the lines for emergency calls and communications.
• Do not drive into damaged areas. Rescue and relief operations need the roads for mobility.
• If there is a need to evacuate, apply the buddybuddy system and follow orders from the Principal/School Head. Wait for your parents to fetch you from the evacuation area and inform the Principal/School Head if you will leave the area.
• Take with you your Earthquake Survival Kit, which contains all the necessary items for your protection and comfort.
