Theme 2 - Earthquakes and Volcanoes Flashcards
plate boundary / margin
The point where two or more plates meet
crust
the solid rock layer that forms the outermost layer of a planet
mantle
the thick, mostly solid layer of Earth that sits between the crust and the core
outer core
the liquid layer of the Earth’s core, located between the mantle and the inner core
inner core
the innermost layer of the Earth
convection current
heat driven cycles that drive the movement of Earth’s tectonic plates in the planet’s mantle
lithosphere
the solid, rigid, outermost layer of the Earth, made up of the crust and the upper mantle
subduction zone
where two tectonic plates collide and one slides beneath the other, diving back into the mantle
oceanic crust
the part of the crust that makes up the seafloor
continental crust
the part of the crust that makes up the continents
role of friction in tectonics
tectonic plates can shift and grind against each other, snagging on each other due to friction
destructive plate boundary
involves an oceanic plate and a continental plate
moving towards each other
oceanic plate subducts as it is more dense
earthquakes occur along subduction zone
collision plate boundary
continental + continental
neither can subduct as they are same density
buckle upwards, forming fold mountains
earthquakes occur due to friction
constructive plate boundary
also known as divergent
oceanic + oceanic
moving apart
magma rises through the gap in crust, forming volcanic islands
rift valley
a lowland region that forms where Earth’s tectonic plates move apart, or rift
hot spot
a magma plume that forms in the middle of a plate, causing it to melt and rising through the crust, forming a volcanic island
conservative plate boundary
- any two types of plate
- moving alongside each other
- different directions + different speeds
- plates lock together due to friction
- pressure builds, rock eventually snaps
- sudden snapping rock + release of pressure causes earthquake
magnitude
size of an earthquake measured on a number scale
seismic wave
vibrations in the Earth that are caused by seismic activity
such as earthquakes + volcanic eruptions
epicentre
the point on the earth’s surface directly above the focus of an earthquake.
focus
where the earthquake originates, deep in the crust
richter scale
measures magnitude of earthquakes from 1 to 9
9 is highest, 1 is lowest
mercalli scale
measures the effects of an earthquake at a given location
distribution of earthquakes
- predominantly on coasts
- pacific ring of fire
- along plate boundaries
primary hazards of earthquakes
- collapsing buildings
- transport / infrastructure damage
- death by crushing
secondary hazards of earthquakes
- tsunamis
- soil salinity
- fires from broken pipes
- further collapse of buildings
PPP
prediction (before event)
the act of estimating when and where a natural hazard will occur
PPP
preparation
a set of actions taken to reduce the impact of a potential disaster
PPP
protection/planning
precautions put in place to reduce the impact of a potential disaster
Methods of earthquake PREDICTION
**hard to achieve **
- texts/tv warnings
- studying patterns
- strange animal behaviour
- drop/rise in groundwater levels
Earthquake PROTECTION - building regulations
- automated shutters
- evacuation zones
- rubber shock absorbers on foundations
- deep foundations
- lattice frame structure
- reinforced bridges
- raised roads
earthquake PREPARATION
- emergency rucksacks
- drills
- evacuation plans
- education on risks
RRR
Relief
emergency aid -> at the site of natural disaster very quickly
RRR
Recovery
long term aid
RRR
Response
Using data from an incident to ensure less damage will occur next time
volcano features
magma chamber
a large underground pool of molten rock, or magma, that sits beneath the Earth’s surface
volcano features
vent
the opening at the top of a volcano where magma, lava, ash, and other materials erupt onto the Earth’s surface
volcano features
secondary vent
a smaller passageway in a volcano that allows magma to escape when the main vent is blocked
usually on one of the flanks of the volcano
volcano features
crater
a bowl-shaped depression that forms at the top of a volcano
volcano features
lava
formed when magma (molten rock) from the mantle reaches the surface and cools to form lava
volcano features
magma
a molten rock mixture
volcano types
stratovolcano / composite
- alternating layers of lava and ash
- convergent plate boundaries
- pyroclastic flow, not lava
- steep sides
- thick lava consistency -> immediately solidifies
volcano types
shield volcano
- hot spots
- thin lava consistency
- lava spreads far and wide before solidifing, forming gentle sides
- divergent plate boundaries
- low, gentle slopes
- frequent but gentle eruptions
volcanic activity
active
liable to erupt
volcanic activity
dormant
has not erupted for many years
volcanic activity
extinct
has not erupted in thousands or millions of years
Distribution of volcanoes
- destructive and constructive plate boundaries
- around the pacific ring of fire
- can be found on hot spots, such as hawaii
primary volcanic hazards
- lava
- ash fall
- pyroclastic flows
- toxic gases
- volcanic bombs
secondary volcanic hazards
- poor air quality -> respiratory problems
- disruption of infrastructure
- disruption of sanitation
- fires
volcanic PREDICTION methods
- steam / gas emission
- tilt meters on slopes of volcano
- thermal monitors
- studying patterns
volcanic PROTECTION methods
- bombing lava flows
- diversion walls for lava flow
- digging ditches
volcanic PREPARATION methods
- emergency rucksacks
- drills
- evacuation plans
- education on risks
benefits/opportunities of living in volcanic zones
- geothermal energy + heating
- fertile soil from ash fall
- tourism -> employment
CASE STUDY: Türkiye-Syria Earthquake 2023
Introduction
- 6th February 2023
- Conservative plate boundary
- 100 mile fault slip
- two quakes: 7.8 +7.5, 9 hours apart
CASE STUDY: Türkiye-Syria Earthquake 2023
Causes
- anatolian + arabian plates forced together due to convection currents
- moving in diff directions at diff speeds -> conservative plate boundary
- pressure builds due to friction
- pressure causes rock to snap along fault line
- snapping rock occurs at focus (18km deep first quake + 10km deep second quake)
- sudden plate movement + release of pressure causes earthquake
CASE STUDY: Türkiye-Syria Earthquake 2023
Impacts
- 6500 cholera cases due to contaminated water
- 115 schools damaged (Syria)
- 1.5 mil homeless in T, 6 mil in S
- 34500 apartments destroyed
- 50,000 dead in T, 6,000 in S
- 115,000 injured in T, 15,000 in S
- 4 million buildings damaged
CASE STUDY: Cumbre Vieja Eruption 2021
Introduction
- a volcano on spanish island la palma in the canary islands
- erupted between 19 September + 13th December 2021
CASE STUDY: Cumbre Vieja Eruption 2021
Causes
- located on a hot spot (magma plume in middle of a plate, causing crust to melt and seep through cracks to reach surface)
- located on african plate, moves 2-3cm a year
- build up of magma swelled a week before eruption
CASE STUDY: Cumbre Vieja Eruption 2021
Impacts
-7,000 forced to evacuate homes
- 1,300 homes destroyed in lava flow
- churches, schools etc destroyed
- farmland + banana plantations destroyed
- size of island increased -> lava flowed into ocean
- flights cancelled, tourist resorts closed -> affected local economy
