Natural hazards flashcards

Definition of a natural event

A naturally occurring physical occurrence

Definition of a natural hazard

A natural event that has the potential to threaten both life and property

Types of natural hazards

Tectonic, atmospheric, geomorphological, biological

Physical factors affecting hazard risk

Deforestation, the enhanced greenhouse effect, climate change

Human factors affecting hazard risk

Wealth, population size, population age, education

What is the plate tectonics theory

The movement of the plates and the activity inside the earth

Ridge push

Where the new crust formed at divergent plate margins is less dense than the surrounding crust and so it rises to form ocean ridges.

Slab pull

Where older, denser tectonic plates sink into the mantle at subduction zones, as these older sections of plates sink, newer and less dense sections of plate are pulled along behind

What plate margins do earthquakes occur on

Destructive, constructive and conservative

Where do volcanoes occur

Destructive and constructing plate margins

What are the processes taking place at destructive plate boundaries

Oceanic and continental plates move towards one another, the oceanic plate subducrs as it is denser, and melts to magma, pressure builds, and escapes through weaknesses in the rock

What are the hazards at destructive plate boundaries

Movement can cause earthquakes

What are the features of destructive plate boundaries

Deep ocean trenches and violent composite volcanoes

What are the processes that take place at constructive plate boundaries

Plates move apart, magma forces to the surface

What are the features of a constructive plate boundary

Shield or fissure volcanoes

What are the hazards of a constructive plate boundary

Movement of plates over the mantle can cause earthquakes

Processes at conservative plate boundaries

Plates are moving past each other

Hazards of conservative plate boundaries

Friction causes plates to get stuck, pressure builds up and is then released which causes earthquakes

Definition of primary effects

The immediate impacts caused by the hazard itself

Definition of secondary effects

Impacts that happen later on, often as a result of the primary effects

Definition of immediate responses

Action taken straight away to save lives, prevent human suffering or mitigate property damage

Definition of long-term responses

Action that goes on for months and years after a disaster

Examples of primary effects of a tectonic hazard

Buildings damaged or destroyed, people killed, injured or made homeless, reduced supply of water, food and electricity, roads blocked

Examples of secondary effects of a tectonic hazard

Tsunamis, avalanches, tourism, income and employment shrinking, landslides, psychological damage to residents

Immediate responses to a tectonic hazard

Rescue efforts, temporary hospitals, emergency aid, temporary shelters

Long-term responses to a tectonic hazard

Earthquake-proof rebuilding of villages and buildings, repairing infrastructure such as schools and hospitals

Primary effects of Chile 2010 earthquake

500 dead, 12,000 injured, 800,000 people affected, moderate building damage, loss of food, water and electricity

Primary effects of Nepal 2015 earthquake

9,000 dead, 20,000 injured, 8,000,000 affected, buildings destroyed, loss of power, food and water, roads blocked and toilets

What was the key information about Chile

H.I.C, 41/187 H.D.I

What was the key information about Nepal

L.I.C, 145/187 H.D.I

Were there differences in the primary effects due to wealth

In Nepal, buildings did not meet regulations

Secondary effects of the Chile 2010 earthquake

Tsunami affecting coastal towns, landslides

Secondary effects of the Nepal 2015 earthquake

Avalanche on Mt Everest, rive flooding, landslides

Immediate responses to the Chile 2010 earthquake

Key roads repaired in 24hrs, 30,000 emergency wooden shelters, power and water restored in 10 days

Immediate responses to the Nepal 2015 earthquake

NGOs sent aid, search and rescue, supplies to remote areas, 30,000 evacuated, food water and medical supplies distributed

Long-term responses to the Chile 2010 earthquake

Took 4 years to make a full recovery

Long-term responses to the Nepal 2015 earthquake

Parts still haven’t recovered, money aid. From other countries rebuilding roads

How did differences due to wealth affect the immediate responses from Chile and Nepal

Nepal required more aid and took more time

How did differences due to wealth affect the long-term responses from Chile and Nepal

Nepal is still recovering

Reasons why people continue to live in areas at risk from a tectonic hazard

Geothermal energy, farming, mining, tourism, family friends and freedom

Definition of monitoring

Using scientific equipment to detect warning signs of events

Definition of prediction

Using historical evidence and monitoring, scientists can make predictions about when and where a hazard may happen

Definition of protection

Designing buildings that will withstand hazards

Definition of planning

Identifying and avoiding places most at risk

Examples of monitoring to reduce the risks from a tectonic hazard

Seismometers used to measure foreshocks, earthquake locations and times are mapped to spot patterns, GPS monitor ground deformation, scientists measure temp of water in streams and rivers

Examples of prediction to reduce the risks from a tectonic hazard

Pattens used to predict when the next earthquake will occur, thermal heat sensors detect changes in temperature or volcano surface, seismometers measure tremors

Examples of protection to reduce risks from a tectonic hazard

Earthquake resistant buildings and infrastructure, people evacuating under instruction of authorities

Examples of planing to reduce risks from a tectonic hazard

Residents learn how to turn off mains gas, electricity and water, preparing emergency aid supplies, evacuation plans

What kind of pressure system is at the equator

Low

What kind of pressure system is 60 degrees north and south of the equator

Low

What kind of pressure system is 30 degrees north and south of the equator

High

Which way do the surface winds blow at the North Pole

Anticlockwise

What is the general global distribution of tropical storms

South of the Tropic of Cancer and north of the Tropic of Capricorn

What sea temperatures are needed for a tropical storm to form

26.5 degrees

Why are tropical storms not found on the equator

The coriolis is effect is not strong enough

What cell are tropical storms found in

The Hadley cell

Where (in terms of degrees) are tropical storms found

Between 5-30 degrees north and south of the equator

What kind of pressure systems are tropical storms found in

Low-pressure systems

What kind of conditions are needed to form a tropical storm

Trade winds, coriolis effect, right temperature and moist conditions

What happens when the ocean surface reaches 26.5 degrees

The warm air above the water rises quickly, which creates very low pressure, which creates strong winds, then the coriolis effect spins warm rising air, as the air rises it cools and condenses which create cumulonimbus clouds, which creates torrential rain, and heat is given off when the air cools=tropical storm

What is the very middle of the tropical storm called

The eye

How tall can tropical storms be

Up to 15km

What is in the eye wall surrounding the eye

Heavy rain and strong winds

What is in the eye of the storm

Clear sky and no wind

How big can the eye wall side to side be

16-48km

How might climate change affect the distribution of tropical storms

Unchanged

How might climate change affect the frequency of tropical storms

May decrease or stay the same in the future, but number of severe ones will increase relative to the total

How might climate change affect the intensity of tropical storms and why

Warmer oceans= higher intensity, every 1 degree increase will lead to 3-5% increase in wind speed

Primary effects of a tropical storm

Winds demolish houses, destroy infrastructure, loss of electricity, power lines and crops, flooding causing deaths and roads blocked

Secondary effects of a tropical storm

Torrential rain can trigger landslides, increased risk of waterborne disease such as chlorela due to water supply contamination from sewage, seawater and industrial waste

Immediate responses to a tropical storm

Evacuation to higher ground, emergency storm shelters, emergency food and water supply

Long-term responses to a tropical storm

NGOS-sustainable development, protection and prediction, repairing damage to buildings, infrastructure and business

Primary effects of typhoon Haiyan 2013

• Destroyed homes and evacuation centres

• People made homeless

• Power, airports and roads damaged

• 5 meter storm surge-90% of Tacloban destroyed

• Rice and seed stocks lost in storm surge

• Argriculture and fishing- US$74 million lost

Secondary effects of typhoon haiyan

• 800,000 oil leak- 10 hectares of mangroves contaminated

• Looting and theft of shops

• Surface and groundwater contaminated from seawater, chemicals from industry, agriculture and sewage systems

Immediate responses to typhoon Haiyan 2013

• 800,000 evacuated by authorities

• Government sent out essential medical equipment and supplies

• Emergency supplies- 3 days by plane

• 1 week-power restored

• 2 weeks-water and food

• Curfew to reduce looting

Long-term responses to typhoon haiyan 2013

• Buildings upgraded and future-proof

• Mo-build zone- East visayas, no dwelling zone

• Storm surge warning system

• Replanted mangroves

• 5-10 years for coconut trees to regrow fruit

Examples of how monitoring can reduce the effects of tropical storms

Satellites