Natural hazards Flashcards
(53 cards)
What is the definition of a natural hazard?
A natural hazard is an event caused by environmental processes that would occur without the presence of humans.
It has the potential to cause harm to the environment, people, or the economy.
What distinguishes a disaster from a natural hazard?
A disaster occurs when harm actually occurs to the environment, people, or the economy.
A natural hazard only has the potential for harm.
Name the four categories of natural hazards.
- Tectonic
- Geomorphological
- Atmospheric
- Biological
These categories help classify natural hazards based on their causes.
List three examples of tectonic hazards.
- Earthquake
- Volcanic eruption
- Tsunami
These events are related to the Earth’s tectonic processes.
What is hazard risk?
Hazard risk is the chance that an area or population will be affected by a natural hazard.
It reflects the likelihood of experiencing harm from natural events.
Identify two factors that increase hazard risk.
- Population growth
- Urbanisation and population density
As more people live in vulnerable areas, the risk increases.
Fill in the blank: High Income Countries (HICs) are more prepared and can cope better with the effects of natural hazards than _______.
[Low Income Countries (LICs)]
This is due to better resources and infrastructure.
True or False: Human activities such as deforestation can decrease the level of hazard risk.
False
Such activities often increase hazard risk.
What factor makes some hazards, like earthquakes, particularly dangerous?
Prediction is difficult or impossible for some hazards, providing no warning.
This lack of predictability increases the risk to populations.
Which natural disaster caused the greatest number of deaths between 1990 and 2018?
Earthquake (the 2004 Indian Ocean earthquake led to approximately 220,000 deaths)
This highlights the devastating impact of tectonic hazards.
What are the four main layers of the Earth?
Inner core, Outer core, Mantle, Crust
The inner core is solid and dense, the outer core is semi-molten, the mantle is semi-molten and less dense, and the crust varies in thickness.
What is the thickness range of oceanic crust?
5−10 km
Oceanic crust is thinner but denser than continental crust.
What is the thickness range of continental crust?
25−90 km
Continental crust is thicker and older than oceanic crust.
What theory explains the movement of tectonic plates?
Slab pull theory
Current theory suggests that the weight of denser oceanic plates subducting drags the rest of the plate along.
What is a plate boundary?
Where two tectonic plates meet
Plate boundaries can be constructive, destructive, or conservative (transform).
Where do most earthquakes occur?
Along all types of plate boundaries, primarily the Pacific ‘Ring of Fire’
Approximately 90% of earthquakes occur in this region.
Where do most active volcanoes occur?
At constructive and destructive plate boundaries
About 75% of active volcanoes are around the ‘Ring of Fire’.
What is a hotspot in geology?
Plumes/columns of magma that escape through the Earth’s crust
Hotspots are not located at plate boundaries.
What are the three main types of plate boundaries?
- Constructive
- Destructive
- Conservative (transform)
Each type has distinct geological activities associated with it.
What occurs at constructive plate boundaries?
Plates move apart, leading to volcanic eruptions and earthquakes
An example is the Mid Atlantic Ridge.
What occurs at destructive plate boundaries?
Plates move together, leading to subduction and associated volcanic eruptions and earthquakes
An example is the boundary between the Nazca plate and the South American plate.
What occurs at conservative (transform) plate boundaries?
Plates move past each other, leading primarily to earthquakes
No volcanic activity typically occurs at these boundaries.
What distinguishes primary hazards from secondary hazards in tectonic activity?
Primary hazards occur directly from the event, secondary hazards result from primary hazards
For example, building collapse is a primary hazard, while fires caused by ruptured gas lines are a secondary hazard.
