Geosciences, Lecture 2

Types of Disasters

Rapid-Onset Disasters

• Definition: Disasters that begin quickly, often before people have time to prepare.

• Duration: Most rapid-onset disasters are of short duration.

Example:

• Earthquake

Slow-Onset Disasters

• Definition: Disasters that take days or weeks to develop, allowing ample preparation time.

• Duration: Most slow-onset disasters are of long duration.

Example:

• Regional Flood

Very Slow-Onset Disasters

• Also known as: Stealth disasters or creeping disasters.

• Duration: Develop over months, years, or even decades.

Examples:

• Sea-level rise

• Droughts

• Groundwater depletion

Chronic Health Disasters

• Definition: Impact of long-term exposure to hazardous Earth materials.

• Health Risks: Can lead to disease and death.

Examples:

• Arsenic poisoning

• Black lung disease

• Silicosis

Disaster Classifications

Primary, Secondary, and Tertiary Disasters

Primary Disaster

• Description: Casualties and destruction from a natural hazard event itself.

Example:

• Wind and wave damage from a hurricane

Secondary Disaster

• Description: Hazardous events triggered by the primary disaster.

Example:

• Collapsed dikes and flooding post-hurricane

Tertiary Disaster

• Description: Long-term societal disruptions due to primary and secondary disasters.

Examples:

1. Housing loss from decay and mold after flood recedes

2. Socioeconomic crises due to job losses

3. Chronic physical and mental health challenges

Specific Example of Earthquake's Impact

• Primary: Collapsed buildings

• Secondary: A firestorm

• Tertiary: Disease among displaced survivors

Disaster Magnitudes and Classifications

Comparison of Disaster Sizes

• Note: No all-purpose scale exists.

Classification Scales:

• Earthquake: Moment Magnitude Scale

• Hurricane: Saffir-Simpson Scale

• Tornado: Enhanced Fujita Scale

Factors Influencing Consequences:

• Applied force

• Area affected

• Duration of the event

• Number of people affected

• Economic cost of the event

Comparing Hurricanes:

• Hurricanes: Hurricane Tip vs. Hurricane Katrina

Informal Descriptions of Disasters

Local Disaster

• Characteristics:

  • Affects a small area

  • Causes few casualties

  • Causes small economic losses

  • Results in no long-term societal disruptions

Major Disaster

• Characteristics:

  • Affects a broad region

  • Causes large losses of life and property

  • Causes major economic losses

  • Results in long-term societal disruptions

Examples of Minor and Major Disasters

• Minor: A disaster from a landslide

• Major: A disaster from a hurricane

Statistical Measures of Disasters

Recurrence Interval (RI)

• Definition: Average time between successive events of a given size.

• Requirement: A historical record is necessary to determine RI.

Annual Probability (AP)

• Definition: Likelihood of an event happening in a given year.

• Formula:
  $AP = \frac{1}{RI}$

• Note: A larger AP value means a disaster is more likely to happen that year.

Example Calculation:

• For a 93-year RI, the events occurred:

  • 1645, 1801, 1837, 1960, and 2017

• Year intervals:

  • 1801 − 1645 = 156 years

  • 1837 − 1801 = 36 years

  • 1960 − 1837 = 123 years

  • 2017 − 1960 = 57 years

• Total:
  $156 + 36 + 123 + 57 = 372$
  $\frac{372}{4} = 93$

Example for a 1.1% AP

• Formula:
  $AP = ! \%$

• Calculation:
  $AP = 0.011 \times 100 = 1.1$%

The Human Toll of Disasters

Key Points

• Media reporting typically focuses on fatalities.

• Other components to consider include displaced individuals and economic impacts.

Definitions:

• Evacuees: Internally displaced people remaining in their country.

• Refugees: Individuals who travel to other countries due to disasters.

Economic Impact Considerations:

• Costs to repair property and infrastructure

• Value of lost economic activities

Notable Historical Examples of Disasters

Challenges in Disaster Statistics

Inherent Challenges

• The number of affected people often exceeds the number of recorded fatalities.

• Economic losses may not account for secondary or tertiary costs.

• Inaccurate reporting is common especially in developing countries.

• Impact assessments may vary with population growth and inflation.

• Property values can differ vastly between wealthy and impoverished areas.

• Socio-natural disasters complicate analyses, e.g., a famine exacerbated by food exports.

• Disaster classification can be inconsistent among reports.

Economic Costs of Disasters

Overview

• Disasters significantly impact global GDP.

• Average annual losses range from 0.15% to 0.50% of global GDP.

Contributing Factors to Rising Economic Losses

• Increasing number of buildings

• Increasing amount of infrastructure

Disaster Cost Analysis in the USA (1982–2019)

Death Toll Analysis from Natural Disasters

Global Statistics

• Annually, 50,000–100,000 people die from disasters.

Causes of Death Analysis

• The most fatalities arise from meteorological, climatological, and hydrological events.

• Highest fatalities attributed to tropical cyclones.

• Additional significant causes: droughts and storms, volcanic activity, landslides, extreme temperatures, floods, tropical cyclones, wildfires, earthquakes.

Economic Impacts from Natural Disasters

Key Points

• Disasters severely impact gross domestic product (GDP) at national and global levels.

• Average annual losses estimated between 0.15% to 0.50% of global GDP.

• Rising economic losses attributed to increases in the number of buildings and infrastructure.

Disaster Predictions, Forecasts, and Warnings

Definitions

Disaster Prediction

• Description: An estimate of a disaster's character, location, and timing.

Forecasts

• Description: Estimates of weather aiding in disaster prediction.

• Classification:

  • Long-Term: More than 14 days out

  • Short-Term: Less than 3 days out

• Note: Shorter time-frame forecasts are generally more accurate.

Warning Terminologies

• Watch: Indicates conditions are right for a hazardous event.

• Warning: Indicates that a hazardous event is occurring.

Hazard Preparedness

Key Components

• Protocols and procedures are essential for planning.

• Hazard-mitigation efforts assist in reducing consequences of disasters. Example approaches include:

  • Buoys that detect and broadcast flood or tsunami alerts.

  • Clear signage directing people to tornado shelters.

• Communities must establish hazard exposure levels and create relevant zoning laws, building codes, and protocols.

Conclusion

• Disaster preparedness, response, and recovery are crucial components in managing the impact of natural disasters.

• Understanding different types of disasters and their consequences is essential for effective planning and mitigation strategies.