D - Geographic Factors Affecting the Impacts of Geophysical Events Flashcards
What factors can affect the impacts of geophysical events?
Magnitude/frequency, population density, building type, time of day, distance from the event, local geology, secondary hazards, and level of economic development.
Why might a shallow-focus earthquake be more destructive than a deep-focus earthquake?
Less rock absorbs the energy between the focus and surface, so more seismic energy reaches the surface.
How does population density influence hazard impact?
Events in high-density areas can cause greater damage and casualties compared to sparsely populated regions.
Why is building quality an important factor in earthquake damage?
Poorly constructed buildings collapse more easily, while earthquake-resistant buildings reduce fatalities and damage.
Give an example of how time of day can affect an earthquake’s impact.
An earthquake during rush hour may cause more casualties than one at night when fewer people are in transit or crowded areas.
Why might an earthquake’s effect be greater further from the epicentre in some cases?
Local geology can amplify seismic waves; loose sediments may shake more intensely than solid bedrock, even at a distance.
What is liquefaction, and why is it dangerous?
When loose, water-saturated sediments temporarily lose strength under shaking, causing buildings to tilt, sink, or collapse.
Name a secondary hazard that can cause more fatalities than the primary event.
Lahars (mudflows) after a volcanic eruption, or tsunamis after an earthquake.
How can a country’s economic development influence disaster outcomes?
Richer nations typically have better preparedness, stronger infrastructure, and faster emergency response, reducing losses.
What is risk in the context of natural hazards?
The likelihood of loss of life, injury, or damage from a hazard over a given time period.
List three key influences on an individual’s perception of risk.
Past experience with hazards, material well-being (wealth), and personality (risk-taking or risk-averse).
What are three general choices people have when living in a hazardous environment?
Do nothing and accept the hazard, adjust to living with it, or leave the area.
Define ‘hazard profile.’
A description and analysis of a specific hazard, detailing its magnitude, frequency, duration, areal extent, spatial concentration, speed of onset, and regularity.
Give an example of how frequency relates to hazard events.
A 1 m flood might occur every year, while a 2 m flood might occur every ten years in the same location.
What does ‘speed of onset’ refer to?
The time difference between the start of an event and its peak, such as the suddenness of an earthquake vs. the gradual onset of drought.
