GEO TOPIC 1.1 - NATURAL HAZARDS + TECTONIC HAZARDS

natural hazard

a naturally occuring process or event which has the potential to cause damage

geophysical hazards

caused by internal earth processes

hydro-meteorological hazards

caused by weather, water or combination of both

vulnerability

The conditions determined by physical, social, economic and environmental factors or processes which increase the susceptibility of an individual, a community, assets or systems to the impacts of hazards.

vulnerability causes

hunger + disease

unprotected buildings

dangerous locations

poverty

lack of education

rapid pop change

over exploitation of resources

social reasons for impacts of hazards being worse in LICS

poor health system - so if disease more likely to happen

poor housing means limited defense

lack of education means people have a lack of knowledge in what to do during hazards

economic/political reasons for impacts of hazards being worse in LICS

support for people limited bc of low budget of people and country

people in charge might not do anything to support people as they are mostly dictators

environmental reasons for impacts of hazards being worse in LICS

deforestation means trees cant absorb water so more floods

extreme weather in areas

plate margin

the boundary between two tectonic plates

convection

the movement caused within a fluid by the hotter therefore less dense material to rise and colder more denser material to sink

earthquake

a sudden violent shaking of the ground as a result of movements within the earth's crust or volcanic action

volcano

A mountain or hill having a crater or vent through which lava, rock fragments, hot vapor, and gas are being or have been erupted from the earth's crust

inner core

solid part of the center of the earth.

outer core

liquid core

mantle

The layer of hot, liquid and solid material between Earth's crust and core.

oceanic crust

thinner, more dense, younger crust making ocean floor

continental crust

thicker, less dense, older and permanent part of crust

convection currents moving plates

core radiates heat which transfers to the mantle

molten rock rises as it is hotter so less dense

once it rises, the molten rock cools, gets more dense and falls back down

friction from convection currrent causes plates to move

focus of earthquake

the point in the crust where the earthquake happens

seismic waves released by focus

epicenter is surface of crust above focus

effect of focus of earthquake

deeper earthquakes cause less damage as the seismic waves have more crust to travel through and more energy is absorbed

richter scale

measures strength of earthquake

logarithmic scale where each scale is 10 times bigger than last one

e.g. 8 is 10x worse than 7

mercalli scale

means intensity (destruction)

measures effect of earthquake

people eyes - subjective

Conservative plate boundary

the plates move side by side together

they lock in, which leads to a pressure build up.

Eventually the pressure is released as a jolt of energy, creating a fault, the site of an earthquake

no volcanoes as there is no magma

How can tectonic plates cause dangerous natural consequences?

Tectonic plates can cause dangerous natural consequences such as earthquakes, volcanic eruptions and tsunamis due to their movements across the Earth's mantle.

What are the differences between 'convection currents' and 'convection heating'?

The differences between 'convection currents' and 'convection heating' are that 'convection currents' are flows of warm water in the mantle of the earth, meaning the movement of tectonic plates. 'Convection heating' is a process of heating a substance through the change of the same substance on the surface.

What is the connection between 'convection currents' and geological activities?

The motion of the convection currents mean that as it sinks, the molten rock rubs against the crust.This causes the tectonic plates to move , which in turn has an effect on geological activities.

Why are 'tectonic plates' important to our experience of the Earth?

'Tectonic plates' are important to our experience of the Earth because their movement can cause sensitive geological activity such as earthquakes, volcanic eruptions and landforms, which have a major impact on our environment.

What could be the consequences of tectonic plate movements? Choose the correct answer(s).

Select 4 correct answers

A

mountains

B

volcanoes

C

thunder

D

earthquake creations

E

rainfall

F

fault lines

A B D F

What is the role of tectonic plates in the role of volcanic eruptions?

Tectonic plates play a role in the occurrence of volcanic changes by causing their movement across the Earth's mantle, which brings with them volcanic activities and eruptions in various areas.

What is the plate tectonics theory?

Show answer

The idea the the lithosphere, the Earth's outermost shell is divided into huge irregularly shaped pieces.These are called tectonic plates, and this theory underpins our understanding of geological occurrences.

What is Pangea?

Select 1 correct answer

A

a continent

B

a country

C

A super continent from around 200 million years ago.

D

The collective name for the tectonic plates

C

State details of oceanic crust

thin

5-10 km thick

dense

made of basaltic rock

sinks when it meets continental plate

recycled at destructive margins

young - usually less than 200 million years old

can sink

Continental crust details

Thick(20-200 km )

indestructible

older, up to 3.8 billion years old

mainly composed of granite rock

cannot sink

How do convection currents work

The mantle rises to the crust from the heat of the 5500 degrees core

More heat = more dense = rises

as it approaches the crust, it cools, gets less dense, then sinks

ridge push

rising mantle helps plates move away from the ridge with ridge push

This works because mid oceanic ridges are higher in elevation, which means that gravity can pull the surrounding rocks down and away from the ridge.

slab pull

old oceanic subducting plates sink between subductive zones, pulling the rest of the plate behind it

The main plate-driving force according to research and where slab pull isn't effective, ridge push is.

constructive plate margins

oceanic plates move away from each other

Magma breaks through the crust

this leads to shield volcanoes

new crust is formed as a mid-oceanic ridge(a line of volcanoes)

Destructive plate boundaries

Collective term for collision and subductive plate boundaries.Both involve plates moving towards each other

What happens when oceanic and continental plates collide?

The denser oceanic plate is subducted underneath the continental plate.

What forms when oceanic plate melts deeper under a continental plate?

Composite volcanoes are formed.

Collision Plate Boundaries

Two plates made of the same crust are moving towards each other. Both plates are pushed upwards creating young fold mountains. Earthquakes can occur.

What type of lava do composite volcanoes have?

Acidic and very viscous/sticky

What is the characteristic of the sides of composite volcanoes?

Steep sides as the lava solidifies before it flows very far

What is a common feature of eruptions in composite volcanoes?

Violent eruptions

How do the eruption intervals of composite volcanoes compare to other types?

Longer periods between eruptions

What kind of layers are found in composite volcanoes?

Alternate layers of ash and lava

Where are shield volcanoes typically found?

Constructive plate margins

What type of lava do shield volcanoes primarily erupt?

Basaltic lava, non-acidic and very runny

How would you describe the shape of shield volcanoes?

Gentle sides, more wide

What is the main characteristic of the eruptions of shield volcanoes?

Less violent eruptions and shorter periods between eruptions

Tephra

any solid material thrown into the air by a volcano

Benefits of Living at Risk of Tectonic hazards - fertile land

volcanic ash rich in minerals which help to fertilise the land

thus, farmers might want to live near volcanoes

Benefits of Living at Risk of Tectonic hazards - tourism

hot springs and mud pools and volcanoes and ruined sites are sites of tourism

Benefits of Living at Risk of Tectonic hazards - minerals

precious minerals i.e. rubies and diamonds can be found in the metamorphic rock of a volcano

Benefits of Living at Risk of Tectonic hazards - energy

eruptions produce a lot of energy - geothermal energy canbe harnessed to power the area.

Monitoring, prediction of a natural hazard

recording physical changes to help forecast - where might hazard strike

scientific methods to help inform management options

protection from a natural hazard

actions taken before a natural hazard

reduce its impact

planning/ prep for a natural hazard

actions taken to help recovery and response to natural hazards

Example of volcano prediction

2010

increase in earthquake activity beneath eyjafjallajokull ice cap

helped scientists to predict te march/april eruption 2010 using seismometers and remote sensing

Seismometers measure

seismic waves

remote sensing of volcanoes

volcanic shape detected by satellites

Protection from volcanoes - explosives and earth embankments

diverts the flow of lava, done on slopes of mt Etna in Italy

Preparation for volcanoes - hazard maps

shows areas likely to be affected, helps people to know of evacuation sites

Preparation for earthquakes

earthquake drills

earthquake insurance policy

hazard map

Monitoring and prediction of earthquakes

seismic activity

creepmeter-monitor the movements of land

Epicentre

the point on the Earth's surface directly above the focus of an earthquake

focus

The point beneath Earth's surface where rock breaks under stress and causes an earthquake

protection from earthquakes

automatic window shutters to prevent falling glass

fire resistant building materials

computer controlled weights on roofs to reduce movement

use steel in building because steel sways and wont snap