Hazards advanced information

Question 1

What is a destructive plate margin and what hazards can occur there

Answer 1

Where two plates move towards each other.

If it is an oceanic and continental plate the denser oceanic plate subducts below the continental plate. Can create a composite volcano or earthquakes.

Two continental plates will create fold mountains and possibly earthquakes due to pressure build-up.

Two oceanic plates can create deep sea trenches and also volcanic eruptions and earthquakes.

Question 2

What is a constructive plate margin and what hazards can occur there

Answer 2

When two plates move away from each other and the movement creates pressure on the mantle which can cause magma to escape and create a volcano.

If it occurs between oceanic plates the magma can create ocean ridges when it cools down.

If it happens between continental plates it can create a rift valley where the crust between the plates drops down. These valleys are likely to have volcanos in them.

Question 3

What is a conservative plate margin and what hazards can occur there

Answer 3

Where two plates are moving past each other. As plates jerk past each other this causes a build-up of pressure which can lead to earthquakes. Can create fault lines.

Question 4

What is seismicity

Answer 4

The worldwide or local distribution of earthquakes in space time, and magnitude. It refers to the measure of the frequency of earthquakes in a region.

Question 5

What is vulcanicity

Answer 5

The rising of Molten Rock or Magma or other gaseous materials beneath the earth’s crust forcing its way into planes of weakness or Vent of the earth’s crust to escape quietly or explosively to the surface.

Question 6

What are is a pyroclastic flow/nuées ardentes

Answer 6

A mixture of superheated gas, ash and volcanic rock that flows down the sides of a volcano. Travels at high speed and a long distance. Since they travel fast they can cause death and destruction with little warning.

Question 7

What are lava flows

Answer 7

Lava can flow from a vent down the side of a volcano. Speed and distance travelled depends on temperature and viscosity of lava. Low viscosity may travel further. Slow moving allows people time to evacuate but lava will destroy buildings.

Question 8

What are volcanic gases

Answer 8

Gases such as carbon dioxide can be released when a volcano erupts. Can be harmful to humans when inhaled in a large quantity.

Question 9

What is pyroclastic fallout/tephra

Answer 9

Pyroclastic fallout is material that has been ejected from a volcano that falls back down to earth. Fallout can range in size. Pyroclastic fallout can crush people.

Question 10

What is ash fallout

Answer 10

When fallout consists of ash it is called ash fallout. Ash fallout can be harmful if breathed in. It can travel very far.

Question 11

What are mudflows/lahars

Answer 11

Occur when volcanic material mixes with water(from rainfall or melted glacial ice). Flow very quickly and travel very far.

Question 12

What is acid rain

Answer 12

Volcanic gases react with water vapour in the atmosphere. Weak sulfuric acid is created. Can damage ecosystems and cause damage to metal.

Question 13

How is magnitude of volcanos measured

Answer 13

Using the volcano explosivity index. Can be ranked from 0-8 based on how high and far the material is ejected from the volcano.

Question 14

What is the frequency of volcano eruptions

Answer 14

Some volcanos can erupt around every 100,000 years while some every few months. The ones that erupt less frequently are generally larger and more damaging.

Question 15

How regular are volcanic eruptions

Answer 15

Some volcanoes erupt at very regular intervals whereas others may be dormant for very long periods of time but then erupt multiple times in quick succession.

Question 16

How are volcanoes predicted

Answer 16

Changes in ground shape around volcano measured using a tiltometer.

Earthquake sensors to measure seismic activity inside the volcano.

Regularity of eruptions can be used.

Question 17

Where do volcanoes occur

Answer 17

At constructive plate margins where basaltic lava erupts. Eruptions are frequent and not very violent.

At destructive plate margins where andesitic and rhyolitic lava erupts areas of subductions. Erupt violently and not very often.

Question 18

What is a primary impact

Answer 18

Something that happens as a direct result of a hazard.

Question 19

What is a secondary impact

Answer 19

Something that occurs as a result of primary hazards.

Question 20

How are volcanoes prevented

Answer 20

It is not possible to prevent an eruption but authorities can prevent it from doing significant damage by not developing land around volcanoes.

Question 21

How are volcanoes prepared for

Answer 21

Make plans for evacuation.
Individuals can be prepared for example having first aid kits.
Search and rescue and firemen teams on standby.

Question 22

How do people adapt to volcanoes

Answer 22

Strengthen buildings to ensure they do not collapse if a layer of ash falls on them.
Use fertile ground for agriculture.

Question 23

Why do earthquakes happen

Answer 23

Build up of pressure at plate margins. When the plates jerk past each other these vibrations are called the earthquake. Vibrations spread out from the focus which is where the pressure build up occurred.

Question 24

How are earthquakes measured

Answer 24

The Richter scale measures earthquakes based on how powerful the vibrations are. It is logarithmic so magnitude goes up by ten as the number increases by one on the scale.

Question 25

What secondary hazards does an earthquake cause

Answer 25

Tsunamis

Landslides

Soil liquefaction

Question 26

What is the magnitude and frequency of earthquakes

Answer 26

Hundreds of low magnitude earthquakes occur daily. High magnitude earthquakes occur more rarely.

Question 27

How random are earthquakes

Answer 27

Earthquakes seem to be random.

Question 28

How are earthquakes predicted

Answer 28

Scientists can monitor the movement of plates to see which areas could be at risk of earthquakes. It is impossible to predict when they will occur and the magnitude.

Question 29

What is a tsunami

Answer 29

Underwater earthquakes displace large volumes of water. Can travel very quickly. The bigger the earthquake the bigger the wave.

Question 30

What is a landslide

Answer 30

Shaking of the ground can dislodge sediment easily that moves downslope easily.

Question 31

What is soil liquefaction

Answer 31

Can occur when soil is saturated with water and vibrations can cause it to act like a liquid which can cause soil to subside.

Question 32

How frequent are earthquakes

Answer 32

Hundreds of low magnitude earthquakes occur daily however high magnitude earthquakes happen very rarely.

Question 33

How regular are earthquakes

Answer 33

Earthquakes don’t seem to follow any particular pattern or trend.

Question 34

Are earthquakes predicted

Answer 34

It is impossible to tell when an earthquake will hit a certain place however scientists can monitor place tectonic movements to see which areas are at risk.

Question 35

How are seismic hazards prevented

Answer 35

It is impossible to prevent seismic hazards however authorities can prevent people building on areas prone to soil liquefaction or build sea walls to prevent tsunamis.

Question 36

How are seismic hazards prepared for

Answer 36

Authorities can have earthquake warning systems that will monitor for smaller seismic waves which could tell if a larger earthquake is coming. Tsunami warning systems can also bet set up.

Firemen and search and rescue teams can be created for a seismic hazard occurring.

Question 37

How can people adapt to seismic hazards

Answer 37

People can live in earthquake buildings for example by having special foundations that can absorb an earthquakes energy.

In places susceptible to tsunamis people may build their houses with very tall foundations.

Question 38

How do tropical storms form

Answer 38

Over warm waters when warm air rises and condenses it releases energy which gives energy to wind. To form there needs to be an area of low pressure so that air converges and rises, sea water that is at least 27 degrees celsius and to be at least 5 degrees from the equator so the coriolis effect can work.

Question 39

Where do tropical storms form

Answer 39

Around the tropics because that is where water is warm enough.

Question 40

What are tropical storms called in different parts of the world

Answer 40

Caribbean sea - hurricanes.

Bay of Bengal - cyclones.

China sea - typhoons.

Question 41

When do tropical storms lose their energy

Answer 41

When they go over land because their supply of warm moist air is cut off.

Question 42

How do tropical storms move

Answer 42

They move westwards due to the trade winds of the tropics. The coriolis effect causes them to move away from the equator.

Question 43

How do tropical storms spin

Answer 43

Clockwise in the northern hemisphere anti clockwise in the southern hemisphere.

Question 44

How is tropical storm magnitude measured

Answer 44

Using the Saffir-Simpson scale. Storm Katrina was a category 3 when it hit land so its wind speed was around 200 km/hr. The Saffir-Simpson scale also estimates how much damage a tropical storm will do with category one being limited damage and category five being catastrophic.

Question 45

What do high winds do in a tropical storm

Answer 45

Wind speeds can be up to 300km/hr. This means they can destroy buildings and carry things like cars and trees long distances before smashing them into things.

Question 46

What is a storm surge

Answer 46

A large increase in sea levels caused by winds pushing water towards the coast.

Question 47

How do tropical storms cause flooding

Answer 47

Heavy rainfall suddenly can cause river discharge to increase suddenly which could then lead to it bursting its banks.

Question 48

How do tropical storms cause landslides

Answer 48

Water from heavy rainfall infiltrates the soil and rock making it more susceptible to landslides.

Question 49

What are short term responses to Tropical storms

Answer 49

Evacuating people from the areas at risk of the storm.

Question 50

How frequent are tropical storms

Answer 50

There are around 80 tropical storms on average around the world each year.

Question 51

How are tropical storms predicted

Answer 51

Satellites and aircraft determine the current location and intensity of the storm. This information is used along with computer forecast models to predict the future path and intensity of the storm.

Question 52

How can tropical storms be prevented

Answer 52

Tropical storms cannot be prevented but scientists can use them to see which areas are at high risk of tropical storms and avoid developing them.

Question 53

How can tropical storms be prepared for

Answer 53

Governments can plan evacuation routes and teach people how to prepare for a tropical storm.

Question 54

How can people adapt to tropical storms

Answer 54

Reinforced buildings with secure roofs so they are not destroyed by wind and houses on stilts could possibly avoid the risk of flooding.

Question 55

How can vegetation type make wildfires more likely

Answer 55

Closely spaced trees allow fires to spread easily. Some trees like pines contain natural oils which allows them to burn easier.

Question 56

How can fuel type make wildfires more likely

Answer 56

Dry material will burn easier for fires. Large amounts of dry material also allow the fire to burn for longer periods of time and spread.

Question 57

How can climate and recent weather make wildfires more likely

Answer 57

Rain must be sufficient so that vegetation can grow to be fuel for wildfires. Area should have a distinct dry season so there is dry, flammable vegetation. Strong wind provides more oxygen to fuel the fire and help spread it.

Question 58

How can fire behaviour make wildfires more likely

Answer 58

Fire can burn differently. A creeping fire will travel slowly whereas a running fire will travel quickly. Fires can throw out burning debris which helps it spread.

Question 59

What are natural causes of a wildfire

Answer 59

A lightning strike can cause a fire if it occurs without much rain. Volcanic eruptions can also cause wildfires.

Question 60

What are human causes of a wildfire

Answer 60

Cigarette buts dropped carelessly and out of control barbecues or campfires can start fires. Deliberate fires can also be a cause which is called arson.

Question 61

How are wildfires prevented

Answer 61

Educate the public about the risks of using campfires. Provide firebeaters to put out fires before they spread.

Question 62

How do people prepare for wildfires

Answer 62

Emergency evacuation plan and emergency supplies for each household. Emergency shelters available for people.

Question 63

How do people adapt to living in areas susceptible to wildfires

Answer 63

Buildings are made out of fire resistant materials. Fire breaks (gaps between trees) are made around settlements to stop fires spreading to buildings.

Question 64

What is risk sharing

Answer 64

A form of ​community preparedness​, whereby the community ​shares the risk posed by a natural hazard and ​invests collectively​ to mitigate the impacts of ​future hazards​.

Question 65

What is fatalism

Answer 65

Where people accept that there will be a risk but choose to do little about it prior to the event. The response after the event will be reactive but the hazard event will often lead to large loss of life.

Question 66

What is adjustment/adaption

Answer 66

For places which experience regular hazards a response is often to adapt or adjust their behaviour to be able to cope with future events better.