Hazards, Disaster, Earthquakes and Volcanic Hazards

HAZARDS (1)

HAZARDS (1)

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)

HAZARDS (2)

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)

HAZARDS (3)

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

TYPES OF HAZARDS (According to Origin)

Natural, or Anthropogenic Origin

GEOLOGIC Hazards

Natural earth processes or phenomena

(Ex: Tsunami, earthquakes, volcanic eruption)

BIOLOGICAL Hazards

Ex: Plague, epidemics

EXTRATERRESTRIAL Hazards

Ex: Meteorites, asteroids, space satellites

HYDRO-METEOROLOGICAL Hazards

Ex: Combination of meteorological and hydrological hazards

HYDROLOGICAL Hazards

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

METEOROLOGICAL Hazards

Ex: High winds, high seas, storm surges

1991 Pinatubo Eruption

Geological Hazard

2011 Japan Tsunami

Geological & Hydrological Hazard

Covid 19

Biological Hazard

2013 Typhoon Yolanda

Hydrometeorological Hazard

Jakarta flash flood

Hydrological Hazard

2013 Russia Meteorite Impact

Meteorological Hazard

Zika Virus - induces Birth Defects

Biological Hazard

Hazards of Natural Origin

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

Hazards of Anthropogenic Origin

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

TECHNOLOGICAL 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

ENVIRONMENTAL HAZARD

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

SOCIO-ECONIMIC, POLITICAL, AND SECURITY HAZARD

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

Adsorb

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

Absorb

Napupunta sa loob

Acute

short, minor

Chronic

long-term, major

MIINAMATA DISEASE

• 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.

MARAWI SIEGE

Socio-Economic, Political, and Security Hazard

TYPES OF HAZARDS (According to Onset)

Sudden and Slow Onset

Sudden Onset

• Little or no warning

• Minimal time to prepare

• (Ex: Tsunami, Earthquakes)

Slow Onset

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

Stages of Slow Onset

Situation develops > Emergency > Disaster

EFFECTS OF HAZARDS

• Primary Effect

• Secondary Effect

• Tertiary Effect

PRIMARY EFFECT

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

Water damage during flood)

SECONDARY EFFECT

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

TERTIARY EFFECT

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)

Destruction of houses due to tsunami

Primary

Fires after 2011 Japan Tsunami

Secondary

Injury, loss of life, habitat and livelihood

Tertiary

HAZARD ANALYSIS

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.

COMMUNITY HAZARDS AND DISASTER HISTORY CONSTRUCTION

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

• Uses records of past hazard events in the community

HAZARD AND VULNERABILITY MAPPING

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

Hazard and Vulnerability Map

FACTOR ANALYSIS

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 (1)

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).

DISASTER (2)

“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).

DISASTER (3)

“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)

DISASTER IN THE PHILIPPINES

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.”

VULNERABILITY

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

EXPOSURE

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

Disaster Risk

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 Formula

Disaster Risk = Hazard x Vulnerability x Exposure

Disaster Prediction

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.

Cyclic Event

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.

Forecasting

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.

Recurrence Interval

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.

Recurrence Interval Formula

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

Relationship among events

Some events are directly related to others.

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

Feedback Effect

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

Precursor Events

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.

Mitigating Hazards

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

Includes:

Engineering solution

Government Policies

Public Education

SOFT Mitigation SOLUTIONS

• Zoning to prevent buildings in hazardous areas

• Strict building codes to minimize damage.

HARD Mitigation SOLUTIONS

• Riprap along coasts

• Spur dikes

LAND-USE PLANNING

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

INSURANCE

These are designed to help with recovery after a disaster.

Lessens the financial impact of disaster.

Earthquake

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

Earthquakes Types

Tectonic and Volcanic

Tectonic

Sudden movement along faults and plate boundaries

Volcanic

Due to rising lava or magma beneath active volcanoes

Parts of an Earthquake

Hypocenter/Focus, Epicenter

Hypocenter/Focus

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

Epicenter

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

Causes of Earthquakes

Plate Tectonics, Elastic Rebound Theory

PLATE TECTONICS

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

Plates

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

Elastic Rebound Theory

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

Stages of an Earthquake

Foreshocks, Main Shock, Aftershocks

MAIN SHOCK

Major Earthquake

FORESHOCK

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

AFTERSHOCK

Occurs in days or months following a large earthquake.

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

Seismometer

An instrument that measures the ground motion of an earthquake.

2 Seimometer configurations

Vertical- and Horizontal- motion seismometer

Vertical-motion seismometer

Records up-and-down ground motion

Horizontal-motion seismometer

Records back-and-forth ground motion

Intensity

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

Magnitude

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

Magnitude Scales

• Richter magnitude or local magnitude (ML)

• Surface-wave magnitude (MS)

• Body-wave magnitude (Mb)

• Moment magnitude (Mw)

Modified Mercalli Intensity Scale

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.

Richter Magnitude Scale

•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).

Richter Magnitude Scale Formula

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

Potential Earthquake Hazards

• Ground Shaking

• Ground Rupture

• Liquefaction

• Tsunami

• Earthquake-induced Landslide

Ground Shaking

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

Motions of Ground Shaking

Up and Down, and Sideways

Up and down

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

Sideways

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

Ground Rupture

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.

Liquefaction

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.

Sand Boil

___ 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)

Tsunami

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.

Earthquake-induced Landslide

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

This is common in mountainous regions.