Disaster Basics
A serious disruption of a community's functioning involving widespread losses that exceed the ability of the affected community to cope using its own resources.
What is a Disaster?
This element of exposure includes tangible assets like buildings, transport networks, and critical infrastructure.
What is Physical Exposure?
A dangerous phenomenon, substance, or human activity that may cause loss of life or property damage.
What is a Hazard?
The most common earthquake hazard, measured by intensity, which causes the most damage to poorly built structures.
What is Ground Shaking?
Tiny fragments of jagged rock, minerals, and volcanic glass that can collapse roofs and cause respiratory issues.
What is Ash Fall?
The potential loss of life, injury, or destroyed assets which could occur to a system or society in a specific period of time.
What is Disaster Risk?
This element refers to people, households, and community structures that may be harmed.
What is Social Exposure?
The two main classifications of hazards based on their origin (e.g., Geologic vs. Hydrometeorological).
What are Types of Hazards?
A series of enormous ocean waves caused by an underwater earthquake or landslide.
What is a Tsunami?
A high-speed, extremely hot avalanche of gas and volcanic debris.
What is a Pyroclastic Flow?
This term describes whether a disaster is "Natural" (e.g., earthquake) or "Human-induced/Man-made" (e.g., industrial leak).
What is the Nature of a disaster?
Business interruptions and loss of inventory fall under this category of exposure.
What is Economic Exposure?
This refers to the specific damage or disruption caused by a hazard, such as structural collapse or crop destruction.
What is the Impact of a hazard?
The process where water-saturated sediment temporarily loses strength and acts like a fluid during intense shaking.
What is Liquefaction?
A violent mudflow or debris flow consisting of a slurry of pyroclastic material, rocky debris, and water.
What is a Lahar?
These can be primary (physical damage), secondary (outbreaks of disease), or tertiary (long-term economic decline).
What are the Effects of Disasters?
This type of exposure involves the degradation of natural resources, such as forests, coral reefs, and water sources.
What is Environmental Exposure?
A hazard that is caused by another hazard, such as a fire caused by an earthquake.
What is a Secondary Hazard?
The literal breaking or shifting of the earth’s surface along the trace of a fault.
What is Ground Rupture?
Rock fragments that are "ejected" from a volcano like cannonballs during an explosive eruption.
What is a Ballistic Projectile?
Disaster Risk is often expressed by this "equation" or relationship involving Hazard, Exposure, and Vulnerability.
What is Risk = Hazard x Exposure x Vulnerability?
The characteristics and circumstances of a community or asset that make it susceptible to the damaging effects of a hazard.
What is Vulnerability?
Hazards that happen over a long period, such as drought or sea-level rise.
What are Slow-onset Hazards?
The downward vertical motion of the Earth's surface, which can be triggered by the settling of sediments during a quake.
What is Earthquake-induced Ground Subsidence?
Increased seismic activity, swelling of the volcano (ground deformation), and changes in gas emissions.
What are Signs of Impending Volcanic Eruptions?