Natural Hazards, Mitigation, and Adaptation

Events that occur as part of the natural cycles of earth and may cause potential damage to a community.

An event that causes widespread losses (human, economic, and environmental) and disrupts the normal

functioning of a community is called a disaster

Vulnerability- defined by the UN Office for Disaster Risk Reduction

it refers to the “characteristics and circumstances of a community, a system, or asset that make it susceptible to

the damaging effects of a hazard.”

Climate Change

A key driver of increasing hydrometeorological disasters, especially global warming and sea level rise.

A challenge to humankind.

Flooding is a global concern & increasing in its intensity. It is forecasted that temperature increase of 3 -4oC could

result in displacement of nearly 330 million people only through flooding.

A 1 metre sea level rise would make at least 56 million peop le environmental refugees in the developing world.

Some Climate Change Impacts (IPCC)

In 2100 : half of the world’s population will sufffer from water stress

Subtropical zones: Less precipitation and increased desertification

Tropical zones: Increased health risks

High latitudes: permafrost decrease

Coastal zones: coastal erosion; storm surges; salt water intrusions

Cost of global warming in 2050: 300 billion USD per year

Hazards Caused by Geologic Processes

1. Earthquakes- this are the vibrations of the Earth caused by rapid release of energy.

List of Active Fault

* Marikina Valley Fault :

Montalban San Pedro

Biñan San Mateo

Carmona Marikina

Santa Rosa Pasig

Calamba Taguig

Tagaytay Muntinlupa

Oriental Mindoro

• FOCUS = place deep within the Earth and along the fault where rupture occurs

• EPICENTER = geographic point on surface directly above focus

• SEISMIC WAVES = produced by the release of energy

– move out in circles from the point of rupture (focus)

– 2 types: surface & body (travel inside & through earth’s layers)

• P waves: back and forth movement of rock; travel thru solid, liquid, gas

• S waves: sideways movement of rock; travel thru solids only

• Seismographs record earthquake waves

• Richter scale = measurement of energy released based upon wave amplitude (size of vibration)

a) Ground Shaking- the vibration of the ground due to plate movement or seismic waves during an earthquake.

b) Surface faulting- the tearing of the ground when the movement of a fault deep within Earth breaks through to ground

surface.

c) Tsunamis- very high, large waves or seismic sea waves caused by the sudden movement of the ocean floor due to

earthquakes, volcanic eruptions, man-made explosions, and on some occasions, landslides.

2. Volcanic Eruptions

The location of the Philippines in the Pacific Ring of Fire is near the subduction zone of the Pacific Plate. It may be followed

by other related hazards such as lahar flow, ash fall, pyroclastic flow, ballistic projectiles, emission of volcanic gases an d

lava flow.

3. Landslides

Landslide occurs in sloping terrain. Usually, if the soil is not compact and devoid of vegetation, gravity can drive soil and

rocks to slide. Landslide can be triggered by wind, water, rainfall or earthquake.

a) Rainfall-induced landslides – In sloping areas, the gravitational descent of loosened soil makes it possible for landslides

to occur. This is a common phenomenon in places with tropical climates after very intense and long rains during the wet

season.

b) Earthquake-induced landslides – This type of landslide happens during or after an earthquake when a piece weakened

landslides off primarily due to gravity. This may be due the natural makeup of the soil consisting of a softer layer beneath

solid bedrock, man-made activities that induce erosion such as deforestation, excavation, mining and quarrying, or thunder

and other vibrations from natural ground activities.

Hazards Caused by Hydrometeorological Phenomena

1. Tropical Cyclones

Also known as typhoons for those occurring in the Northwest Pacific and hurricanes for those developing in the Atlantic

and Northeast Pacific are storm systems characterized by rapidly spiraling storms, low pressure center, and intensely strong

winds.

a) Strong winds- the strength of winds can destroy lightweight structures and uproot plants and trees.

b) Heavy rainfall leading to flooding- some typhoons are associated with continuous and heavy rains.

2. Monsoons - seasonal winds. The Philippines experiences two monsoons every year the Amihan and the Habagat.

Amihan- northeast monsoon is characterized by cold gusty wind with little or no precipitation. Blows to the east.

Habagat- southwest monsoon is characterized by hot and humid atmosphere with frequent heavy rainfall. Blows to the west.

3. Tornadoes - A tornado or locally known as ipo-ipo is a rapidly swirling condensation funnel whose narrow end comes in

contact with the ground.

Hazard Caused by Coastal Processes

Coastal Erosion- the seawater through wave actions, tidal currents, strong winds, or a combination of all of these loosens

the soil on the shore, which eventually destroys the integrity of land.

Submersion- As global atmospheric temperatures rise, oceans and seas become warm and expand. Rising global

temperatures also speed the melting of glaciers and ice caps.

Storm Surges- may occur in coastal areas when typhoons make landfall. The strong winds of the cyclone push the waters

toward the shore, sometimes generating huge waves capable of destroying sea walls and structures facing the sea.

Saltwater Intrusion- the movement of minerals and salts from coastal seas to freshwater aquife rs.