Tectonic Hazards Flashcards
describe the earths structure
core- hot and under a lot of pressure
inner core - solid
outer core - liquid
mantle surrounds core solid that can flow
crust thin layer compared to mantle and core
name 2 types of crust
continental and oceanic
how do continental and oceanic crusts differ (3)
they have different chemical composition, thickness and density
what do the crust and upper mantle form together
a shell at earths surface called lithosphere
describe the lithosphere
it is broken into fragments called tectonic plates -
where do 2 tectonic plates meet
at a plate margin
what do the 3 types of plate margin tell us
they describe how the plates move
name 3 types of plate margins
constructive
destructive
and conservative plate margins
what is the cause of an earth quake
the interaction between the tectonic plates and the mantle beneath
how do we know that tectonic plates move
evidence by gps measurements over time
what are the 3 theories for what makes tectonic plates move
convection
ridge push
slab pull
describe the convention theory for the movement of tectonic plates
the cores temperature causes magma to rise in the mantle and sink in the core
when it cools currents flow in the lithosphere building up pressure
and carrying the plates
describe the ridge push theory for the movement of tectonic plates
at constructive margin ocean ridge form above ocean floor
beneath the ridge the mantle melts
molten magma rises as the plates move apart and cool down to form new plate material
as lithosphere cools it becomes dense and starts to slide down away from ridge causing plates to move away from each other
describe the slab pull theory for the movement of tectonic plates
at destructive margin denser plates sink back into mantle and the rest of the plate is pulled along behind it
where are volcanoes found
on land and sea at constructive and destructive plate margins are located
where are earthquakes found
on land and at sea at constructive, destructive and conservative plate margins are located
what is the name of the large band of volcanoes and earthquakes which circle the pacific ocean
ring of fire
what are hot spots
when volcanoes or earthquakes are in the middle of plates rather than along a plate margin. The crust is thin
describe a constructive plate margin
occur when tectonic plates move apart from each other usually few centimeters each year
when do conservative plate margins occur
when tetonic plates move parellel to each other. plates moving side by side
why are earthquakes found at conservative plate margins
as the plates move past each other fiction causes them to become stuck
presure builds up until the rock fractures in an earthquake
an example of conservative plate margin
san andreas fault
what is a hazard risk
probability a hazard will happen
5 factors that effect hazard risk
geography - rock type or shape of coast line
magnitude - biigger more impact
frequency
population distribution
level of development - more money better prepared
when does hazard risk increase
1 when number of people vulnerable to risk increases eg more living by hazard
2 increase in frequency and strength of hazard
3 increase in people not able to cope with the hazard - without money or knowledge
why are earthquakes found at constructive plate margins
tectonic plates move away from each other by ridge push and slab pull
magma cools and forms a new plate
rift valley forms
why are earth quakes found at destructive plate margins
tectonic plates converge
pressure builds between them rock fractures causing earth quake
what is difference between primary and secondary effects of hazards
primary effects happen immediatly eg loss of life
secondary happen latter and often caused by primary eg disease
what are immediate responses to tectonic hazaeds
1 warning,
2 send rescue teams,
3. treat injured,
4provide shelter, food and drink,
4 recover bodies,
5 put out fires
what are long term responses to tectonic hazards
repair and rebuild infastructure, restore utilities, resettle people, recover ecconomy, install monitor equipment
who monitors earthquakes
seismologists
how can death and destruction be reduced
monitor-changes in shape use seisometer
predict-using monitoring info
protect - earthquake proof buildings and infastructure and sea walls against tsunami
plan- evacuation routes, exclusion zones, educate - first aid training
why do people live near earth quakes and volcanoes (7)
1 geothermal energy is a major source of power
2 land around a volcanoe is full of nutients
3 tourism creates jobs
4 people want to live near family and friends
5 it is cheaper to stay than to move
6 they dont understand the risks
7 they have confidence in the safety measures
what is an earthquake
vibration in crust on plate margin, sudden and without warning
why do earthquakes happen
caused by stress between plates as they pass one another producing energy
how are earthquakes measured
on the rictor scale- the higher on the scale the more damage
why does the damage of the earthquake vary
it is effected by population density
depth of earthquake deepr -= less damage
geology - type of rock - solid = less damage
strength
