geography - natural hazards

Lithosphere

Lithosphere

crust and top layer of upper mantle

Asthenosphere

more dense in the upper part of mantle

what plates collide at a destructive plate

oceanic plate subducts underneath the continental plate because it is more dense

example of destructive

south american plate over the Nazca plate

what happens when pressure is released in destructive boundaries

they jolt into position, this sudden change causes seismic waves

what is a constructive plate boundary

when plates move apart from each other, this causes magma to come up and form new land

example of constructive plate boundary

mid atlantic ridge in the atlantic ocean

what is a conservative plate boundary

Plates slide past each other and build up friction, they can get stuck and cause earthquakes

Example of a conservative plate boundary

San Andreas Fault in the USA

what is a collision plate boundary

2 continental plates moving towards each other. As they are the same plate, they are forced upwards to create fold mountains as they are the same density

example of collision boundary

Himalayas between the indian and eurasian plates

definition of hazard

naturally occurring events that pose potential risk and threats to people / or property

definition of risk

the likelihood of harm taking place based on the exposure to the hazard

why do people live in high risk areas?

tourism, volcanoes give fertile land for businesses, frequency etc

characteristics of continental crust

below land, less dense, granite rock, cannot sink, can't be renewed or destroyed

characteristics of oceanic crust

below ocean, thinner, more dense, can sink, can be renewed or destroyed, basaltic rock

how do some tectonic plates move

convection currents in the asthenosphere is caused by heat rising, starts to sink when it gets cooler. change of density allows plates to form

what is the slab pull theory

states the gravity and the plates are the ones responsible for the plate tectonics through subduction process

what is the ridge push theory

known as the sliding plate force is a proposed driving force for plate motion in plate tetonics

why is volcanic activity found near plate margins

the earths crust is more unstable which causes magma to reach the surface. Volcanoes are usually found at destructive and constructive plate margins.

Where are composite volcanoes found?

80% are found at destructive plate boundaries

Where are shield volcanoes found?

Constructive plate boundaries

characteristics of composite volcanoes

steep slopes,tall cone with a narrow base, made of layers of ash, volcanic gases don't escape the lava easily

characteristics of shield or base volcanoes

gentle slopes, low cone with wide flanks, made of numerous lava flows, low viscosity, mild frequent eruptions

definition of hotspot

large mantle plume, commonly found at shield volcanoes

explain how to predict a volcano using VEI

volcanic explosive ty index takes the height of the volcano and how long they typically last to predict the frequency of them

explain how to predict a volcano using Seismometers

they see the pattern of the the years when they erupt and see whether it has gone over that limit and is likely to erupt

explain how satellite imagery can predict a volcano

thermal scanning shows the events of magma rising

what can be done to protect people during volcanoes?

you can't really do much. You can evacuate people from their homes to a safe location, people can wear long sleeves to protect them from ash fall. Sometimes people divert lava into the sea to prevent it from reaching a populated area

how can you plan for a volcanic eruption?

Exclusion zones can be designated. People. an practice covering their eyes, nose and mouth to prevent gas fumes.

explain how we can use electromagnetism to predict earthquakes

We can pass magnetic waves through rocks and detect any fractures that could suggest that the plates have gone under pressure which could lead to an earthquake

how can shock absorbers protect people from earthquakes

They are dampers which go between the house and ground to withstand vibrations which could cause lots of damage to property

how can cross bracing help protect people from earthquakes

Uses X shape frames to stiffen the frame of a building and helps resist rocking. They are usually placed around lifts so they don't malfunction when evacuating people

how can counter weights help protect people from earthquakes

They are made of steel or concrete . When the building starts to vibrate, the weights move in the opposite way to help reduce damage

how can you plan for an earthquake

High value land such as hospitals and office books can be protected. Maps can be produced to show the effects of an earthquake or identify the area of risks from damage. For example, after the Tohoku earthquake, every year on the 1st of september they practice an earthquake drill to prepare them for any more potential earthquakes

Advantage of living by a tectonic hazard: geothermal energy

In Iceland, the blue lagoon is heated by geothermal energy which attracts 1.5 million tourists a year. Leading to the multiplier effect

Advantage of living by a tectonic hazard : tourism

Attracts tourists, which creates employment, leading to the multiplier effect