College of Education
School of Continuing and Distance Education2014/2015 – 2016/2017
UGRC 144
Science and Technology in Our
Lives/Geohazards
Session 1 – Introduction to Hazards and
Disasters
Dr. Patrick Asamoah SakyiDepartment of Earth Science, UG, Legon
Session Overview
• In everyday life, we always negatively associate events like earthquakes, tsunami and floods, with disasters.
• In this section;– The terms disaster and hazard are defined and explained
– Explanation will be given as to why the mere occurrence of an event like an earthquake should not be regarded as the occurrence of a disaster.
– Also, the conditions under which an event becomes a disaster will be explained.
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Session Outline
The key topics to be covered in the session are as follows:
• Topic One - Hazard
• Topic Two - Classification of Hazards
• Topic Three - Vulnerability
• Topic Four - Disaster
• Topic Five - Disaster prevention and management
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Reading List
• Read Chapter 4 of Environmental Geology 4th Edition – by Carla W Montgomery (1995)
• Read Unit 1, Section 1 of UGRC 140 II Geohazards –Institute of Continuing and Distance Education
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HAZARDTopic One
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What is a Hazard
• Hazard is defined as:
• Phenomena that pose a threat to people, structures, or economic assets and which may cause a disaster. They could be either man-made or naturally occurring in our environment.
• A natural or man-made phenomenon that may cause physical damage, economic loss and threaten human life and wellbeing
A trigger event. A trigger-event that sets off a disaster
Hazard means an event which has the potential to cause a disaster, and can be either natural or man-made.
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CLASSIFICATION OF HAZARDSTopic Two
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Classification of Hazards
• Hazards are classified into two main groups, namely:
– natural hazards and
– man-made hazards.
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Classification of Hazards
• There are two types of natural hazards, namely; – fast-impact and
– slow-onset hazards, (e.g. chemical spill, fire), or technological in nature (e.g. nuclear generator failure).
• Examples of fast impact natural hazards include earthquakes, floods, cyclones, hurricanes, tornadoes, landslides, tsunami, volcanic eruption, insect infestation and wild-fires.
• Slow onset natural hazards include epidemics of biological origin (e.g. SARS, Bird Flu, Ebola),drought, and famine.
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Classification of Hazards
• Man-made hazards are also of two types;
– sudden
– long term;
• Sudden man-made hazards include transport, structural and technological accidents (e.g. chemical spill, fire)
• Long term man-made hazards (e.g. nuclear generator failure).
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VULNERABILITYTopic Three
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What is Vulnerability
• Vulnerability is a term used to describe exposure to hazards and shocks.
• It is defined as the extent to which a community, structure, service, and/or geographic area is likely to be damaged or disrupted by the impact of a particular hazard, on account of their nature, construction and proximity to hazardous terrain or a disaster prone area.
• People are more vulnerable if they are more likely to be badly affected by events outside their control.
• For a disaster to occur the hazard must come in touch with unsafe – conditions which make a population vulnerable to that particular hazard
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DISASTERTopic Four
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What is a Disaster
• A disaster is;– A sudden, adverse event bringing great damage, loss,
great distress, destruction and devastation to life and property.
– A serious disruption of the functioning of society, causing a calamity, widespread human, material or environmental losses which exceed the ability of the affected society to cope using its own resources.
– The disruption of human ecology that exceeds the capacity of the community to function normally (WHO).
– Sudden ecologic phenomenon of sufficient magnitude to require external assistance
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What does a Disaster do?
• A disaster influences the mental, socio-economic, political and cultural state of the affected area.
• It completely disrupts the normal day to day life in a society
• It negatively influences the emergency systems
• Normal needs and processes like food, shelter, health, etc. are affected and deteriorate depending on the intensity and severity of the disaster
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DISASTER PREVENTION AND MANAGEMENT
Topic Five
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How do we Prevent Disaster?
• We now know that:
DISASTER = HAZARD + VULNERABILITY
• Human-induced hazards that can potentially result in a disaster can be avoided or prevented
• Naturally-occurring hazards cannot be entirely controlled, but disasters associated with them can be reduced by following certain directives.
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How do we Prevent Disaster?
• To avoid, prevent or manage a disaster;
– Eliminate Hazard No Disaster
– Eliminate Vulnerability No Disaster
– Keep Hazard and Vulnerability Apart.
– Reduce Vulnerability and/or hazard, especially human-induced hazard.
• The specific disaster prevention and/or management techniques will be discussed under each geological hazard in subsequent sections
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Summary
• In this section;
– we have defined and explained; disaster, hazard and vulnerability.
– We have seen that hazards only result in a disaster if they coincide with vulnerable conditions.
– We have seen that to avoid a disaster, we must prevent a hazard from coming in contact with vulnerable societies.
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END
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