Hazards, Disaster, Earthquakes and Volcanic Hazards

Potentially damaging physical events, phenomena, or human activities that may cause injury, loss of life, damage to property, social and economic disruption, or environmental degradation (UNISDR, 2007)

A dangerous (natural) phenomenon, substance, human activity or condition that may cause loss of life, injury or other health impacts, property damage, loss of livelihood and services, social and economic disruption, or environmental damage (RA No. 10121)

Potential or existing condition that may cause harm to people or damage to property or the environment (Australian Natural Disasters Organization)

Natural, or Anthropogenic Origin

Natural earth processes or phenomena

(Ex: Tsunami, earthquakes, volcanic eruption)

Ex: Plague, epidemics

Ex: Meteorites, asteroids, space satellites

Ex: Combination of meteorological and hydrological hazards

Ex: flash floods, storm surges, rain-induced landslides

Ex: High winds, high seas, storm surges

Geological Hazard

Geological & Hydrological Hazard

Biological Hazard

Hydrometeorological Hazard

Hydrological Hazard

Meteorological Hazard

Biological Hazard

Geologic, Biological, Extraterrestrial, Hydro-meteorological, Hydrological, Meteorological Hazard

Technological, Environmental, and Socio-Economic, Political, and Security Hazard

Little or no warning to precede the incident. Originate from industrial accidents, dangerous procedures, infrastructure failures, or certain human activities. May cause loss of life or injury, property damage, social and economic disruption, or environmental degradation

Pose a threat from the surrounding environment. Encompassing the broad spectrum of acute and chronic effects of industrial, agricultural, and naturally occurring microorganisms, chemicals and radiation in our soil, water, air, food, and wastes

Caused by criminal and human violence. Pose a threat to the security of a great number of people. Motivated perhaps by political or economic reasons

Di totally naabosrb parang naattract or nagaacumalate lang; vicinity of the body

Napupunta sa loob

short, minor

long-term, major

• miinamata river, dumped mercury by one of the companies, tap water ng mga tao yon

• post-war

• neurological disease caused by severe mercury poisoning.

• A congenital form of the disease can also affect fetuses in the womb and may cause cerebral palsy.

• Signs and symptoms include ataxia, numbness in the hands and feet, general muscle weakness, loss of peripheral vision, and damage to hearing and speech. In extreme cases, insanity, paralysis, coma, and death follow within weeks of the onset of symptoms.

Socio-Economic, Political, and Security Hazard

Sudden and Slow Onset

• Little or no warning

• Minimal time to prepare

• (Ex: Tsunami, Earthquakes)

• Slow to develop (Ex: Drought, Civil Strife)

Situation develops > Emergency > Disaster

• Primary Effect

• Secondary Effect

• Tertiary Effect

Result of the process itself (Ex: Collapse of building during an earthquake, landslide, or hurricane

Water damage during flood)

Caused by the primary effect (Ex: Fires due to earthquakes, Flooding caused by a landslide into a lake or river)

Long term effects that are set off as a result of a primary event (Ex: Loss of habitat caused by a flood, Crop failure due to volcanic eruption)

Primary

Secondary

Tertiary

Identification, study, and monitoring of any hazard to determine its potential, origin, characteristics, and behavior (UNISDR, 2007)

Its purpose is to:

• Provide descriptions of the hazards

• Help in setting priorities corresponding to the need for protection

• Assist in designing the appropriate DRRM system, plan, programs, and services.

• Existing hazards and the disasters that the community experienced are identified.

• Uses records of past hazard events in the community

Areas in the community that are vulnerable to a specific hazard are identified and then located in the map.

Describes the characteristics of the hazard in terms of the following (Heijmans and Victoria, 2001):

• Frequency

• Duration

• Speed of Onset

• Intensity

• Probability

• Forewarning

• Manageability

Disaster is a serious disruption of the functioning of a society, causing widespread human, material, or environmental losses which exceed the availability of the affected society to cope using only its own resources (RA No. 10121; UN DMTP, 1992).

“An event, natural or man-made, sudden or progressive, which impacts with such severity that the affected community has to respond by taking exceptional measures” (Carter, 1991).

“An event which deprives people of life, property or livelihood and which taxes the resources of the survivors beyond their collective capacity to cope” (OFDA)

In the PDRRM or Philippine Disaster Risk Reduction and Management Act 2010, which adopted the definition of UNISDR:

“A dangerous phenomenon, substance, human activity, or conditions that may cause loss of life, injury or other health impacts, property damage, loss of livelihood and services, social and economic disruption, or environmental damage.”

The extent to which a community’s structure, services, or environment are likely to be damaged or disrupted by the impact of hazard.

The number of people, property, systems, or other elements present in hazardous areas that are thereby subject to potential losses (UNISDR, 2011b).

A disaster caused by a hazard (typhoon, flood, storm surge, earthquake, tsunami, volcanic eruption, landslide, etc.) and its impact on the vulnerability of structures, population, economy, etc.

As such, one can summarize that there is no risk if there are no people to be affected.

Disaster Risk = Hazard x Vulnerability x Exposure

A catastrophic natural event is unlikely to be stopped. As such, the best way is to predict the event and to avoid it as soon as possible.

It is impossible to predict exactly the occurrence of such event, as such, predictable cycles in natural events are used.

These are events that occur at predictable intervals.

Most recurring natural events are not truly cyclic due to many factors that affect its behavior.

Most events appear to be at random and at unpredictable intervals.

Scientists cannot predict exactly when an event will occur.

Instead they forecast based on experience and studies about the change that a hazardous event will occur in a region within a few decades.

To do forecasting, scientists applies the idea that

“The past is the key to the future”

These intervals relate to the probability that a natural event of a particular size or magnitude will happen within a certain period of time or within a certain frequency.

To estimate such interval, we rank each event according to their magnitude from 1 to n, then one can get the Recurrence Interval (R) for a given annual maximum by using the formula:

  Where

R – Recurrence Interval

N – Number of data

M – Rank

Some events are directly related to others.

For example, a tsunami could be caused by an earthquake or an underwater landslide.

Some processes result in more rapid changes, called feedback effect.

Some major natural events are preceded by a series of smaller precursor events.

These events could be used as a warning of an impending disaster.

Refers to the efforts to prepare for a disaster and reduce its damage.

Includes:

Engineering solution

Government Policies

Public Education

• Zoning to prevent buildings in hazardous areas

• Strict building codes to minimize damage.

• Riprap along coasts

• Spur dikes

In order to reduce losses from natural disasters:

• Find where they occur

• Restrict development in that area

For example

• Prevent development near faults

• Limit development on floodplains

These are designed to help with recovery after a disaster.

Lessens the financial impact of disaster.

A weak to violent shaking of the ground due to sudden movement of rock material below the surface.

Tectonic and Volcanic

Sudden movement along faults and plate boundaries

Due to rising lava or magma beneath active volcanoes

Hypocenter/Focus, Epicenter

Also known as focus. Point inside the Earth where the earthquake originated.

The point on the surface of the earth directly above the focus.

Plate Tectonics, Elastic Rebound Theory

The plates tend to move in a continual slow motion, and cause interaction with its neighboring plates causing stress on margins.

___ are large slabs of the Earth’s lithosphere which rides on a partially hot molten layer of the upper mantle or asthenosphere.

Explains that most earthquakes are produced by the rapid release of energy stored in rocks that had been subjected to great stress.

Upon exceeding the rock strength, it suddenly ruptures, causing vibrations of an earthquake

Foreshocks, Main Shock, Aftershocks

Major Earthquake

Possibly results from the development of the smaller cracks in the vicinity of what will be the major rupture

Occurs in days or months following a large earthquake.

Occurs due to readjustment of the crust after the slip from the mainshock.

An instrument that measures the ground motion of an earthquake.

Vertical- and Horizontal- motion seismometer

Records up-and-down ground motion

Records back-and-forth ground motion

The effect or consequence of an earthquake’s ground shaking at a locality on the Earth’s surface.

A number that characterizes the relative size of an earthquake. It is based on measurement of the maximum motion recorded by a seismograph.

• Richter magnitude or local magnitude (ML)

• Surface-wave magnitude (MS)

• Body-wave magnitude (Mb)

• Moment magnitude (Mw)

In 1902, an Italian scientist named Giuseppe Mercalli devised a scale for defining intensity by systematically assessing the damage that the earthquake caused.

Note that the specification of earthquake intensity depends on a subjective assessment of damage, and of the perception of shaking, not a direct measurement with an instrument.

•Developed by Charles Richter

•Based on the maximum amplitude of motion that would be recorded at a station about 100 km from the epicenter

•The original Richter scale works well only for shallow earthquakes that are close to the seismometer station – now called local magnitude (ML).

Where I stands for the intensity of the earthquake and I0 represents a zero-level earthquake the same distance from the epicenter.

• Ground Shaking

• Ground Rupture

• Liquefaction

• Tsunami

• Earthquake-induced Landslide

It is the disruptive up-down and sideways movement or motion experienced during an earthquake, and is responsible for the collapse of structures.

Up and Down, and Sideways

First felt by people near the epicenter; not felt by people far from epicenter.

Felt after up and down by people near epicenter; first felt by people far from epicenter.

The displacement on the ground due to movement of a fault.

The structures that are only build across fault lines may experience collapse, whereas structures build adjacent to the fault may survive.

Process where the unconsolidated sediments loose grain to grain contact during ground shaking, thus act almost liquid.

In some water-saturated sediments, the water may be expelled from the spaces between grains. The escaping water carries the sediment along as it rapidly flows to the surface as sand boils and mud volcanoes.

___ or sand volcanoes occur when water under pressure wells up through a bed of sand. The water looks like it is boiling up from the bed of sand, hence the name. (Ex: Shinhua site, Taiwan)

Are giant ocean waves that rapidly travel across oceans.

These sea waves are formed due to the disturbance of the ocean floor by an earthquake or landsides.

___ are failures in steep or hilly slopes triggered by ground shaking.

This is common in mountainous regions.