Chapter 1:
- Epicentre: the point on the surface directly above where the rocks fractured. Focus: the actual point below
the surface where the rocks fracture, and the energy is released
Diverging Boundary: shallow focus 10-70km depth
- New crust added at mid ocean ridge, occur in oceans away from people and are not strong.
Convergent zone with subduction: - denser plate subducts, deep oceanic trench
- OO (shallow to deep focus 0-700km): Seismic activity as two plates collide. 700km as plate descended far
enough to aesthenosphere to melt. Energy released from points along descending plate produce earthquake.
- OC: (shallow focus 0-20km): although there is a large area of plate interaction, seismic activity is shallow focus
but can be large in magnitude and very destructive
Transform Boundary: shallow focus 0-20km depth
- Most destructive, plate movement is not smooth, elastic potential energy is built up and suddenly released as
seismic waves. San Andres fault line
- At divergent plate boundaries, earthquakes tend to be weak and shallow. Transform plate boundaries, have
shallow, but very powerful earthquakes. At convergent plate boundaries, where two continental plates collide
earthquakes are deep and are very powerful.
P waves – primary waves
- Compression waves, fastest and first to arrive at seismometer station.
S waves – secondary waves
- Transverse waves, travel slower than p waves and arrive later
Surface waves – ground waves: (slow but are the most destructive)
- L waves: shake the surface side to side, slow but travel far distances
- R waves: cause up and down vibrations and not as destructive as love waves.
Earthquake hazards:
- Collapsing structures: as ground moves, it transfers energy to anything attached to earth, transforming into
sharing forces which tear structures apart.
- Landslides: as boulders and rocks give way, ground slides downwards damaging areas build beneath and
buildings, cars… carried downwards at avalanche speeds
- Fires: fires breakout and broken water pipes make it hard to fight the blaze.
- Liquification: some soils, when vibrated rapidly, begin to act like a liquid, sinking everything on it.
- Floods: excessive ground shake can damage dams… and the flow of water cannot be halted.
Tsunamis: giant wave which occurs when ocean water is suddenly displaced. Caused by earthquakes, asteroids
hutting ocean, volcanic eruption. Occur near subduction zones, edge of overriding plate in a subduction zone may
become locked and pulled metres downwards over large area, when plate is released, waver is uplifted creating a
large wave traveling in all directions and impacts land.
How hazards measured:
- Seismometers: large weight that remains still and the ground shakes underneath as it draws a line. Detects P
waves and S waves before surface waves
- The Richter scale: measures amplitude of seismic waved on a logarithmic scale.
- Modified Mercalli scale classifies earthquakes by their effects
Volcanoes:
- They are openings through which hot gasses, molten rock and ash from earth’s mantle can escape to surface.
- Viscosity: liquids resistance to flowing. High silica = high viscosity = honey
- Effusive: dominated by the eruption of lava. Magma contains large amounts of dissolved gasses. Emerging
gases have time and space to escape from lava being erupted.
- Explosive: ash is the dominant product; volcano explodes and more dangerous. Gasses unable to escape due
to insufficient openings to surface, gasses expelled at the same time as lava. Explosive lave can have a silica
content of 60% or higher. Extra silica content has come from sediment dragged into mantle with subducting
plate, or from overlying plate as rising magma melts through it and incorporates some of its minerals.
,Volcano Hazards:
- Ash eruption (explosive): Ash falling on agricultural land, building collapse, lightning, and weather events.
- Lava flows (effusive): slow moving, little threat, rarely stoppable so destroys everything in its path.
- Pyroclastic flows (explosive): consists of rock particles small enough to be blown high into air by explosion but
not held there continuously. Also forms when viscous lava dome at the top of a volcano collapses triggering
loose sediments to tumble down with hot gasses. 1000°, hot avalanche frictionless speeds up to 700km/hr.
combination of extremes heat, mass and velocity is why it’s so dangerous.
- Lahars (explosive): type of flooding, fast flowing water mixes with ash and loose rubble to give it consistency
of wet cement. It can flow down the side of steep volcanoes at 60km/hr or more, growing massively erodes
the gillies and riverbanks in flows through. The combination of high mass and high speeds is why it’s so
dangerous.
- Poisonous gas emissions – atmospheric contaminations (explosive and effusive): causes local and global
effects. Sulphur dioxide gas dissolve in atmospheric water to form droplets of sulphuric acid. If aerosols are
blown into troposphere, they can cover surrounding regions with a mist that obscures the sun until rainfall
clears the air, can be short term and long term. They spread around the world by jet stream current and can
partially block sunlight reaching ground level by absorption or reflecting into space. Can lead to red skies:
Mount Pinatubo. Global temperatures could drop.
, Chapter 2: impact of natural disasters on the biosphere
Impact explosive and effusive eruptions have on the biosphere and atmosphere
Sphere Explosive volcanic eruption Effusive volcanic eruption
Biosphere Very destructive, cause death of people, Less destructive to humans, animals’ vs
animals, plants in large numbers and areas. explosive but destroy large amounts of
Negative impacts habitat due to lava flows
Ash Negative impacts
- Asphyxiation (deprived of oxygen) from - Release of toxic gases; carbon dioxide
ash flows which can travel large distances which impacts human/animal health long
in the form of Vog term, can cause suffocation
- Cause respiratory issues (asthma attack) - Acid rain affects cops, animals, humans
- Death by burial under heavy ash - Carbon dioxide poisoning affects plants if
- Ash falls – contaminate water supplies gas saturates the soil and penetrates
and acidify systems through the roots
- Mafic lava flows can destroy all living
Pyroclastic flow things in its path, vegetation due to
- Direct burns/death from hot & fast flows extreme heat
- Production of lahars that trap and bury - Large lava flows can travel many km2
anything in its path, eventually solidifies Positive impacts:
and changed topography of landscape
- Flows and lahars cover agricultural land - As mafic lava cools and forms basaltic
with volcanic material. Flatten forests rock, rock will weather away producing
fertile soil for plant growth
Lava - The creation of mew island for new
- Direct burns/death from hot lava habitats (Hawaiian Islands)
exploding from volcano - Source of geothermal energy for living
- Destroy and change landscape – thick things and humans to access and use
viscous lava form rigid shapes The 2018 Kilauea (Hawaii) eruption
Positive impacts: - Destroyed 657 homes
- Creation of new islands for new habitats - Created a toxic atmosphere (Vog and
- Volcanic materials eventually weather Laze)
away to produce fertile soil-plant growth - Threat to endangered species of birds
- Extinct volcanoes are mineral rich (for - No deaths reported. Injuries only to those
humans to extract and use) who didn’t follow safety instructions.
The 1883 eruption of Krakatoa
- Killed at least 36, 000 people
- Busted ear drums of many sailors near
explosion
- Killed all animals off the islands &
destroyed 70% of island including
vegetation.
- Tsunami created by explosion &
pyroclastic flows killed many marine
organisms, destroyed homes & habitats
of surrounding islands (java/Sumatra)
Atmosphere Both short term and long-term effects Less impact on atmosphere
- Decrease in temperature which last for Short term impacts
days-weeks for small eruptions and for - Lower amount of SO2 released into
several years for larger eruptions stratosphere
- Fall in temperature can be local or global - Less SO2 released
- Poor air quality due to large amounts of
- Epicentre: the point on the surface directly above where the rocks fractured. Focus: the actual point below
the surface where the rocks fracture, and the energy is released
Diverging Boundary: shallow focus 10-70km depth
- New crust added at mid ocean ridge, occur in oceans away from people and are not strong.
Convergent zone with subduction: - denser plate subducts, deep oceanic trench
- OO (shallow to deep focus 0-700km): Seismic activity as two plates collide. 700km as plate descended far
enough to aesthenosphere to melt. Energy released from points along descending plate produce earthquake.
- OC: (shallow focus 0-20km): although there is a large area of plate interaction, seismic activity is shallow focus
but can be large in magnitude and very destructive
Transform Boundary: shallow focus 0-20km depth
- Most destructive, plate movement is not smooth, elastic potential energy is built up and suddenly released as
seismic waves. San Andres fault line
- At divergent plate boundaries, earthquakes tend to be weak and shallow. Transform plate boundaries, have
shallow, but very powerful earthquakes. At convergent plate boundaries, where two continental plates collide
earthquakes are deep and are very powerful.
P waves – primary waves
- Compression waves, fastest and first to arrive at seismometer station.
S waves – secondary waves
- Transverse waves, travel slower than p waves and arrive later
Surface waves – ground waves: (slow but are the most destructive)
- L waves: shake the surface side to side, slow but travel far distances
- R waves: cause up and down vibrations and not as destructive as love waves.
Earthquake hazards:
- Collapsing structures: as ground moves, it transfers energy to anything attached to earth, transforming into
sharing forces which tear structures apart.
- Landslides: as boulders and rocks give way, ground slides downwards damaging areas build beneath and
buildings, cars… carried downwards at avalanche speeds
- Fires: fires breakout and broken water pipes make it hard to fight the blaze.
- Liquification: some soils, when vibrated rapidly, begin to act like a liquid, sinking everything on it.
- Floods: excessive ground shake can damage dams… and the flow of water cannot be halted.
Tsunamis: giant wave which occurs when ocean water is suddenly displaced. Caused by earthquakes, asteroids
hutting ocean, volcanic eruption. Occur near subduction zones, edge of overriding plate in a subduction zone may
become locked and pulled metres downwards over large area, when plate is released, waver is uplifted creating a
large wave traveling in all directions and impacts land.
How hazards measured:
- Seismometers: large weight that remains still and the ground shakes underneath as it draws a line. Detects P
waves and S waves before surface waves
- The Richter scale: measures amplitude of seismic waved on a logarithmic scale.
- Modified Mercalli scale classifies earthquakes by their effects
Volcanoes:
- They are openings through which hot gasses, molten rock and ash from earth’s mantle can escape to surface.
- Viscosity: liquids resistance to flowing. High silica = high viscosity = honey
- Effusive: dominated by the eruption of lava. Magma contains large amounts of dissolved gasses. Emerging
gases have time and space to escape from lava being erupted.
- Explosive: ash is the dominant product; volcano explodes and more dangerous. Gasses unable to escape due
to insufficient openings to surface, gasses expelled at the same time as lava. Explosive lave can have a silica
content of 60% or higher. Extra silica content has come from sediment dragged into mantle with subducting
plate, or from overlying plate as rising magma melts through it and incorporates some of its minerals.
,Volcano Hazards:
- Ash eruption (explosive): Ash falling on agricultural land, building collapse, lightning, and weather events.
- Lava flows (effusive): slow moving, little threat, rarely stoppable so destroys everything in its path.
- Pyroclastic flows (explosive): consists of rock particles small enough to be blown high into air by explosion but
not held there continuously. Also forms when viscous lava dome at the top of a volcano collapses triggering
loose sediments to tumble down with hot gasses. 1000°, hot avalanche frictionless speeds up to 700km/hr.
combination of extremes heat, mass and velocity is why it’s so dangerous.
- Lahars (explosive): type of flooding, fast flowing water mixes with ash and loose rubble to give it consistency
of wet cement. It can flow down the side of steep volcanoes at 60km/hr or more, growing massively erodes
the gillies and riverbanks in flows through. The combination of high mass and high speeds is why it’s so
dangerous.
- Poisonous gas emissions – atmospheric contaminations (explosive and effusive): causes local and global
effects. Sulphur dioxide gas dissolve in atmospheric water to form droplets of sulphuric acid. If aerosols are
blown into troposphere, they can cover surrounding regions with a mist that obscures the sun until rainfall
clears the air, can be short term and long term. They spread around the world by jet stream current and can
partially block sunlight reaching ground level by absorption or reflecting into space. Can lead to red skies:
Mount Pinatubo. Global temperatures could drop.
, Chapter 2: impact of natural disasters on the biosphere
Impact explosive and effusive eruptions have on the biosphere and atmosphere
Sphere Explosive volcanic eruption Effusive volcanic eruption
Biosphere Very destructive, cause death of people, Less destructive to humans, animals’ vs
animals, plants in large numbers and areas. explosive but destroy large amounts of
Negative impacts habitat due to lava flows
Ash Negative impacts
- Asphyxiation (deprived of oxygen) from - Release of toxic gases; carbon dioxide
ash flows which can travel large distances which impacts human/animal health long
in the form of Vog term, can cause suffocation
- Cause respiratory issues (asthma attack) - Acid rain affects cops, animals, humans
- Death by burial under heavy ash - Carbon dioxide poisoning affects plants if
- Ash falls – contaminate water supplies gas saturates the soil and penetrates
and acidify systems through the roots
- Mafic lava flows can destroy all living
Pyroclastic flow things in its path, vegetation due to
- Direct burns/death from hot & fast flows extreme heat
- Production of lahars that trap and bury - Large lava flows can travel many km2
anything in its path, eventually solidifies Positive impacts:
and changed topography of landscape
- Flows and lahars cover agricultural land - As mafic lava cools and forms basaltic
with volcanic material. Flatten forests rock, rock will weather away producing
fertile soil for plant growth
Lava - The creation of mew island for new
- Direct burns/death from hot lava habitats (Hawaiian Islands)
exploding from volcano - Source of geothermal energy for living
- Destroy and change landscape – thick things and humans to access and use
viscous lava form rigid shapes The 2018 Kilauea (Hawaii) eruption
Positive impacts: - Destroyed 657 homes
- Creation of new islands for new habitats - Created a toxic atmosphere (Vog and
- Volcanic materials eventually weather Laze)
away to produce fertile soil-plant growth - Threat to endangered species of birds
- Extinct volcanoes are mineral rich (for - No deaths reported. Injuries only to those
humans to extract and use) who didn’t follow safety instructions.
The 1883 eruption of Krakatoa
- Killed at least 36, 000 people
- Busted ear drums of many sailors near
explosion
- Killed all animals off the islands &
destroyed 70% of island including
vegetation.
- Tsunami created by explosion &
pyroclastic flows killed many marine
organisms, destroyed homes & habitats
of surrounding islands (java/Sumatra)
Atmosphere Both short term and long-term effects Less impact on atmosphere
- Decrease in temperature which last for Short term impacts
days-weeks for small eruptions and for - Lower amount of SO2 released into
several years for larger eruptions stratosphere
- Fall in temperature can be local or global - Less SO2 released
- Poor air quality due to large amounts of
