Natural hazards Flashcards
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.
What are some primary hazards of volcanic eruptions?
- Ash
- Pyroclastic flow
- Lava flow
- Gas emissions
- Volcanic bombs
These hazards can cause immediate destruction and health risks.
What are some secondary hazards of volcanic eruptions?
- Lahars
- Landslides
- Climate change
- Floods
Secondary hazards can arise after the primary event and can cause further damage.
What are some immediate responses to tectonic hazards?
- Rescue teams search for survivors
- Medical assistance for the injured
- Shelter provided for the homeless
- Food and water provided
Immediate responses focus on saving lives and addressing urgent needs.
What are some long-term responses to tectonic hazards?
- Rebuilding homes and infrastructure
- Improving building regulations
- Implementing better evacuation plans
- Government planning improvements
Long-term responses aim to reduce future risks and improve resilience.
What was the magnitude of the 2015 Nepal earthquake?
7.8
The earthquake struck on April 25, 2015, causing widespread destruction.
What were some immediate effects of the 2015 Nepal earthquake?
- Approximately 9000 deaths
- Over 20,000 injuries
- Damaged schools and health facilities
- Loss of tourist income
The earthquake had devastating social and economic impacts.
What is the GDP per capita of Nepal as of 2015?
Under $1000
Nepal is one of the poorest countries in the world.
What was a significant long-term response to the Nepal earthquake?
- Introduction of earthquake drills
- Stricter building codes
- $200 million grant for rebuilding
- New government task force for future planning
These measures aim to enhance preparedness for future seismic events.
What was the GDP per capita of Italy as of 2016?
Over $31,000
Italy is classified as a High-Income Country.
What were some immediate responses to the 2016 Italian earthquake?
- Rescue workers sent to affected areas
- Temporary hospitals set up
- Mobile kitchens serving meals
- Emergency communication lines established
These actions aimed to address immediate health and safety needs.
What are some advantages of living in tectonically active areas?
- Fertile soils
- Tourism opportunities
- Mining of minerals
- Geothermal energy
These advantages can provide economic benefits despite the risks.
What are some social reasons people may choose to live in tectonically active areas?
- Family ties
- Long-term residence
- Confidence in improved technology and prediction
Emotional and social factors often influence residency decisions.
What natural attractions draw tourists to volcanic areas?
Eruptions, hot springs, and geysers
Examples include Iceland and Mount Vesuvius in Italy.
What economic effect can tourism in volcanic areas have?
Creates employment and may lead to the multiplier effect.
What are the potential dangers of ash and pyroclastic flows?
Deaths and injuries, destruction of crops, food shortages, and price increases.
Name the four key management strategies to reduce risks from tectonic hazards.
Monitoring, Prediction, Protection, Planning.
What equipment is used to monitor active volcanoes?
- Seismometers
- Lasers and tiltmeters
- Remote sensing
- Gas sensors
What do seismometers detect?
Earth movements and tremors.
What do gas sensors monitor in relation to volcanic activity?
Increases in gases such as sulphur and radon.
What change in groundwater levels can indicate an earthquake?
Changes in groundwater levels.
Can accurate predictions of volcanic eruptions be made?
Yes, but accurate timings are not possible.
Are earthquakes predictable in terms of date, time, or location?
No, it is impossible to predict.
What measures are taken for protection against volcanic eruptions?
- Evacuation and exclusion zones
- Strengthening roofs for ash weight.
What is a common practice for earthquake preparedness?
Earthquake drills - ‘drop, cover and hold on’.
What type of building design helps protect against earthquakes?
Earthquake-resistant building design, such as reinforced steel cross braces.
What planning strategies are used for volcanic and earthquake risks?
- Hazard mapping
- Risk assessment
- Evacuation plans
- Education and drills.
Fill in the blank: Hazard mapping and risk assessment are used to identify areas at _______.
[greater risk].
What can planning help to reduce the effects of an earthquake or volcanic eruption?
- Prepare emergency aid and distribution
- Earthquake/volcano drills
- Evacuation routes
- Stockpile supplies.
True or False: HICs have less capability to prepare for tectonic hazards than LICs.
False.
