DRRR

Etymological origin of the word "disaster"

Derived from des (bad) and aster (star), literally meaning "evil star" from ancient beliefs about star alignments.

Definition of a disaster (RA 10121)

A severe disruption of a community or society's day-to-day functioning involving extensive physical, financial, material, or ecological losses exceeding its capacity to cope.

Four phases of the Disaster Cycle

1. Mitigation (Reduce impact)

2. Preparedness (Plan response)

3. Response (Act immediately)

4. Recovery (Restore community)

Distinction between Hazard, Exposure, Vulnerability, and Risk

• Hazard: Danger / source of harm

• Exposure: Presence in hazard-prone area

• Vulnerability: Susceptibility to damage

• Risk: Expected loss over time

Four main types of vulnerability

1. Physical: Related to geography, structures, and population layout.

2. Social: Inability of individuals/groups to tolerate impacts based on inherent demographic traits.

3. Economic: Financial limitations of a population or government.

4. Environmental: Degradation of ecological systems reducing resilience.

Five classifications of Natural Hazards

1. Geological

2. Meteorological

3. Hydrological

4. Climatological

5. Biological

Five classifications of Man-Made Hazards

1. Technological

2. Environmental

3. Societal

4. Infrastructure

5. Transportation

Four cause-based types of earthquakes

1. Tectonic: Plate movements

2. Volcanic: Magmatic activity

3. Collapse: Cavern or underground mine collapses

4. Explosion: Nuclear or chemical detonations

Five primary hazards associated with earthquakes

1. Ground shaking

2. Ground rupture

3. Tsunami

4. Liquefaction

5. Earthquake-induced landslide

Difference between Earthquake Magnitude and Intensity

• Magnitude: Amount of energy released at the source (measured via seismograph).

• Intensity: Perceived strength of shaking and impact experienced at a specific location.

Six primary volcanic hazards

1. Pyroclastic Flow (Superheated rock/gas mixture)

2. Ashfall (Fine glass/rock particles)

3. Ballistic Projectile (Ejected rock fragments)

4. Lahar (Volcanic mudflow/debris flow)

5. Volcanic Gases (Toxic emissions like $SO_2$, $CO_2$, $H_2S$)

6. Lava Flow (Molten rock streams)