tectonics Flashcards
(254 cards)
1
Q
intra plate earthquakes
A
These occur in the middle or interior of tectonic plates and are much rarer than boundary earthquakes
2
Q
volcanic hazards
A
Associated with eruption events
3
Q
volcano
A
A landform that develops around a weakness in the Earth’s crust from which molten magma, volcanic rock and gases are ejected and extruded
4
Q
seismic hazards
A
Generated when rocks within 700km of the Earth’s surface come under such stress that they break and become displaced
5
Q
tectonic hazards
A
These include earthquakes and volcanic eruptions as well as secondary hazards such as tsunami and represent a significant risk in some parts of the world in terms of loss of life, livelihoods and economic impact
6
Q
what % of earthquakes are found along plate boundaries
A
95%
7
Q
what 3 patterns does the distribution of earthquakes show
A
The oceanic fracture zone (OFZ)
The continental fracture zone (CFZ)
Scattered earthquakes in continental interiors
8
Q
The oceanic fracture zone (OFZ)
A
activity found in mid-ocean ridges. E.g. the mid-Atlantic ridge.
9
Q
The continental fracture zone (CFZ)
A
activity found in mountain ranges e.g. across the Himalayas.
10
Q
Scattered earthquakes in continental interiors
A
along old fault lines.
E.g. the Church Stretton Fault in Shropshire
11
Q
what does the type of plate boundary determine about a volcano
A
whether a volcano exists and what type it is
12
Q
how many volcanoes are there globally
A
500
50 erupt each year
13
Q
what is the voilence of a volcanic eruption determined by
A
by the number of dissolved gases in the magma and how easily they can escape.
14
Q
what is a volcano called that forms away from a plate boundary
A
hot spots
15
Q
where do intra plate earthquakes happen
A
Intra-plate earthquakes happen in the middle of plates.
16
Q
why do intra plate earthquakes happen
A
Scientists think that they occur when stresses build up in ancient faults - causing them to become active again.
17
Q
why are intra plate earthquakes harder to predict
A
they don’t occur in well-defined patterns along plate margins
18
Q
what is a volcanic hotspot
A
an area in the mantle from which heat rises as a hot thermal plume from deep in the Earth – often called a ‘magma plume’.
High heat and low pressure at the base of the lithosphere enable melting of the rock
19
Q
what % of earthquakes happen in the Ring of Fire
A
70%
20
Q
example of a hotspot/magma plume
A
Hawaii
21
Q
what 4 scientists produced the theories of plate tectionics
A
Harry Hess
Alfred Wegener
John Tuzo Wilson
James Hutton
22
Q
what theory did Harry Hess propose
A
proposed that ridges on the ocean floor were the result of molten rock rising from the asthenosphere.
23
Q
what theory did Alfred Wegener propose
A
published two articles about a concept called continental drift.
24
Q
what theory did John Tuzo Wilson propose
A
proposed that volcanic island chains (e.g. Hawaii) are created by fixed ‘hotspots’.
25
what theory did James Hutton propose
that the processes of erosion, deposition and uplift were connected and operated continuously – driven by the Earth’s internal heat.
26
what was James Huttons theory called and what year
Theory of the Earth
1785
27
what did the Theory of the Erath suggest
the processes of erosion, deposition and uplift were connected and operated continuously, driven by the Earth’s internal heat.
28
what cycle did James Hutton come up with
the rock cycle
29
what did the rock cycle suggest
where rock particles were transported to sea, buried, solidified and then later lifted back to the Earth’s surface through tectonic processes.
30
what was the name of Alfred Wegeners theory and what year
Continental drift
1912
31
what did continental drift suggest
200 million years ago, a supercontinent called Pangaea began to break into pieces, its parts moving away from one another. The continents we see today are fragments of that supercontinent.
32
how did Alfred Wegener support his continental drift theory
by pointing to matching rock formations and similar fossils across continents.
33
what was the name of Harry Hess' theory
seafloor spreading
34
what did sea floor spreading suggest
discovered that the oceans were shallower in the middle and identified the presence of mid-ocean ridges which were as high as 1.5km above the flat sea floor.
He envisaged that oceans grew from their centres, with molten material (basalt) oozing up from the Earth’s mantle, creating seafloor spreading either side.
35
what did john tuzo wilson come up with
hotspot theory
36
hotspot theory by wilson
John proposed in 1963 that plates might move over fixed ‘hotspots’ in the mantle, forming volcanic island chains.
In 1965, he followed this discovery with the idea of a third type of plate boundary – transform faults (conservative plate boundaries) – regarded as the missing piece in the puzzle for plate tectonic theory.
37
what is the lithosphere broken up into
into seven major and several minor parts – tectonic plates.
These plates move relative to each other over the asthenosphere.
There are a number of processes which drive their movement
38
asthenosphere definition
the part of the mantle below the lithosphere, where the rock is semi-molten.
39
what processes drive the movement of tectonic plates
mantle convection
slab pull
subduction
seafloor spreading
paleomagnetism
40
mantle convection
Heat produced by the decay of radioactive elements in the Earth’s core heats the lower mantle – creating convection currents.
These hot, liquid magma currents are thought to move in circles in the asthenosphere – thus causing the plates to move.
41
slab pull
Newly formed oceanic crust at mid-ocean ridges becomes denser and thicker as it cools.
This causes it to sink into the mantle under its own weight –pulling the rest of the plate down with it.
42
subduction
Subduction is the process of a plate being destroyed.
As two oceanic plates OR an oceanic and continental plate move towards each other, one slides under the other into the mantle – where it melts into an area called the subduction zone (the circle on the diagram).
43
seafloor spreading
This is the process of new crust pushing tectonic plates apart.
In the middle of many oceans there are mid-ocean ridges, or underwater mountain ranges.
These are formed when hot magma (molten rock) is forced up from the asthenosphere and hardens – forming new oceanic crust.
44
paleomagnetism
1950’s, studies of palaeomagnetism confirmed that the sea floor was spreading.
Every 400,000 years or so, the Earth’s magnetic fields change direction i.e. the magnetic north and south swaps.
When lava cools and becomes rock, minerals inside the rock line up with the Earth’s magnetic direction (polarity) at the time.
45
what theory is now less accepted
mantle convection
46
when two tectonic plates meet what do they form
a plate boundary
47
what are the areas next to plate boundaries called
plate margins
48
what are the 3 plate boundaries
convergent
divergent
conservative
49
what are convergent also known as
destructive margins
50
what are divergent also known as
constructive
51
what are conservative also known as
transform
52
what happens at a divergent plate boundary
two plates are moving apart (diverging) – leading to the formation of new crust.
In oceans, this divergence forms mid-ocean ridges and on continents it forms rift valleys.
53
how far can Mid-ocean ridges of underwater mountains extend for
60,000 km
54
eg of a divergent plate boundary with oceanic crusts
mid-atlantic ridge
55
earthquake hazards at mid ocean ridges
Shallow-focus earthquakes (less than 70km into the crust) occur frequently, but they pose little threat to humans as they are small and underwater.
56
volcanic hazards at mid ocean ridges
Submarine volcanoes can occur, some which grow above sea level to create new islands. E.g. Iceland on the mid-Atlantic ridge. These are generally less explosive and more effusive, especially when they occur underwater.
57
effusive meaning
a type of eruption in which lava steadily flows out of a volcano.
58
what are rift valleys (divergent)
When continental plates move apart, the crust stretches and breaks into sets of parallel cracks (faults)
The land between these faults then collapses, forming steep-sided valleys called rift valleys.
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example of a divergent plate boundary with continental crusts
east african rift valley
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earthquake hazards at rift valleys
Similar to mid-ocean ridges – shallow and low magnitude.
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volcano hazards at rift valleys
Yes! The thinning crust allows magma to rise
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the subduction zone
Broad areas where two plates are moving together. Often the thinner, more dense oceanic plate descends beneath the continental plate.
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locked fault
In a subduction zone, as plates move together they can get stuck due to frictional resistance. Such faults may store strain for extended periods, that is eventually released in a large magnitude earthquake.
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the benioff zone
An area of seismicity corresponding with the slab being thrust downwards in a subduction zone.
65
what happens at a convergent plate boundary
plates move towards each other
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what are the three types of convergent plate boundary dependent on
the type of plate found there
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what are the 3 types of continental plate boundaries
Oceanic meets continental
Oceanic meets oceanic
Continental meets continental
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destructive convergent boundaries
oceanic meets continental
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oceanic meets continental convergent boundaries
Oceanic crust is more dense than continental, so when they collide, the oceanic crust subducts underneath into the mantle. This is marked by deep ocean trenches
As the oceanic plate subducts, the continental plate is folded and slowly pushed up, forming a chain of fold mountains
70
earthquake hazards at oceanic meets continental convergent boundaries
Friction between colliding plates causes intermediate and deep earthquakes in the Benioff Zone.
These earthquakes are some of the largest and most damaging
71
volcanic hazards at continental meets oceanic convergent boundaries
Explosive volcanic eruptions are generated as magma created from the melting oceanic plate pushes up through the faults in the continental crust to reach the surface. These are generally less frequent than other volcanoes, but are more destructive.
72
why is there so much tectonic activity around the Pacific Ring of Fire
due to the convergent plate boundary
73
destructive convergent boundaries
oceanic meets oceanic
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what happens when an oceanic plate and an oceanic plate meet at a convergent plate boundary
When two oceanic plates collide, one plate (the denser or faster) is subducted beneath the other – deep ocean trenches occur at this boundary.
75
earthquake hazards at oceanic meets oceanic convergent boundaries
The subduction produces shallow-deep earthquakes, some of which can be very powerful.
76
volcanic hazards at oceanic meets oceanic convergent boundaries
As the subducted plate melts, magma rises to form underwater volcanoes. Over millions of years, these grow to above sea level to form separate island volcanoes, called island arcs.
77
convergent boundaries- collision margin
continental meets continental
78
what happens during a collision margin
both plates have about the same density, and are less dense than the asthenosphere beneath them, neither plate is actually subducted.
Instead, they collide and sediments between them are crumpled and forced up to form high fold mountains. E.g. The Himalayas
Inevitably, there may be some subduction caused when the compressed (and therefore denser) sediments result in plate subduction beneath them.
79
eg of a continental meets continental plate boundary
Nepal sits on the boundary between the Eurasian and Indian tectonic plates. It is a convergent boundary where two continental plates collide
In 2015, Nepal experienced a 7.8 magnitude earthquake.
80
Name the landforms that are formed when an oceanic crust collides with a continental crust.
deep ocean trenches
fold mountains
81
what happens at a conservative plate margin
two plates are sliding past one another – resulting in a major break in the crust between them as they move.
The break itself is called a fault, and where it occurs on a large scale it’s known as a transform fault.
82
earthquake hazards at conservative plate margins
Powerful, but shallow earthquakes can occur due to frictional resistance – the plates stick as they move past one another, causing stress and pressure to build.
83
volcanic hazards at conservative plate margins
none
84
eg of a conservative plate margin
San Andreas fault
85
when was the last major earthquake on the San Andreas Fault
1906 at 8.3 on the Richter scale.
86
how do earthquakes occur
When the plates move against each other they sometimes stick – causing huge amounts of pressure to build up
When the pressure becomes too much, the rock fractures along cracks called faults
Energy is released as seismic waves, which cause the ground to shake.
87
where are seismic waves released from
inside of the Earth’s crust, along the fault.
88
where do seismic waves radiate out from
the focus
89
what are the three main types of seismic waves
Primary ‘P’ waves
Secondary ‘S’ waves
Love ‘L’ waves
90
how do primary 'P' waves travel
P waves are body waves – they travel through the Earth’s body.
They travel through both solids and liquids.
They move in a backwards and forwards motion.
91
how fast are P waves
They are the fastest and the first to reach the surface (8km/sec).
92
when are P waves damaging
only damaging in the most powerful earthquakes
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how do secondary 'S' waves travel
S waves are also body waves – they travel through the Earth’s body.
They travel through solids only.
They move in an up and down motion, perpendicular to the direction of travel.
94
how fast are S waves
They are slower than P waves (4km/sec).
95
how damaging are S waves
They do more damage than P waves.
96
how do love 'L' waves travel
L waves are surface waves – they travel only on the Earth’s surface.
They move in a side to side motion, perpendicular to the direction of travel.
97
speed of L waves
They are the slowest of the three waves (last to arrive).
98
damage caused by L waves
They are larger and cause the most damage.
99
what is the overall severity of an earthquake linked with
linked to the amplitude and frequency of these wave types.
The ground surface may be displaced horizontally, vertically or obliquely (slanted) during an earthquake depending on the strength of individual waves.
100
what does todays research into predicting earthquakes focus on
focuses on precursors, which may suggest a major earthquake is likely to happen
E.g. Foreshocks (small earthquake that happen before a larger one)
101
how are earthquakes predicted
Currently there is no method at accurately predicting when or where an earthquake will strike
we can use our knowledge of plate boundaries to forecast where an earthquake is likely to happen. E.g. areas that have had one big earthquake are likely to have another
102
physical effects of earthquakes
Magnitude (the size of the seismic waves)
Depth (the deeper the hypocentre, the more energy the waves lose along the way)
Distance from the epicentre (the closer you are the stronger it is)
Geology – soft rocks can amplify shaking
103
human effects of earthquakes
Level of development
Population
Level of preparation
The effectiveness of the emergency response
The impact of secondary hazards
104
what are primary effects
Those that happen as a direct result of the earthquake
105
what are secondary effects
Side effects of an earthquake (happen as a result of the primary effects) often causing much more damage.
106
secondary effects of earthquakes
landslides/avalanches
tsunami
liquefaction
107
landslides or avalanches
Slopes fail as the shaking places stress on them resulting in landslides, rock slides, mudslides and avalanches.
108
tsunami
Underwater earthquakes generate a series of big waves.
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liquefaction
When surface rock lose strength and become more liquid than solid. The subsoil loses its ability to support building/infrastructure foundations, so they sink or tilt.
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primary effects of earthquakes
ground shaking
crustal fracturing
111
ground shaking
causes buildings, bridges, roads and infrastructure to collapse
112
crustal fracturing
when Earth’s crust cracks due to the energy that is released.
113
where and why do aftershocks occur
occur in the general area of the original earthquake, and are a result of the Earth ‘settling down’ or readjusting along the part of the fault that slipped originally
114
when do aftershocks occur
can occur weeks, months or even years after an earthquake and in general the larger the earthquake, the larger and more numerous the aftershocks.
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why are aftershocks damaging
They are capable of causing additional damage as well as hampering recovery efforts.
116
eg of bad aftershocks
2011 a 6.3 magnitude aftershock struck Christchurch in 2010, which caused more damage and loss of life than the original.
117
why are volcanoes closely related to plate margins
they are areas in the Earth’s crust through which lava, ash and gas can erupt
118
what can volcanoes do
Volcanoes get bigger as more and more eruptions occur. Lava cools to form rock after each eruption and builds over time.
Small numbers occur on hotspots.
119
over the past 300 years how many people have died as a result of eruptions
Over the past 300 years, approximately 260,000 people have died as a result of eruptions.
120
what are primary hazards of volcanoes
lava flows
pyroclastic flows
tephra and ash falls
gas eruptions
121
what are lava flows
These are streams of lava that have erupted onto the Earth’s surface.
Due to their heat they destroy everything in their path.
generally not threatening to humans as most of them move slowly as people can move out of their way.
122
how hot can lava flows be
They can reach up to 1170˚c (hot!) and take years to cool completely.
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what are pyroclastic flows
These are a mixture of dense hot rock, lava, ash and gases ejected from the volcano.
Like lava, they destroy everything in their path.
124
how hot can pyroclastic flows be
700
125
how fast can pyroclastic flows be
move very quickly, up to 100km per hour
126
what is tephra
pieces of volcanic rock and ash that blast into the air during eruptions.
127
effects of tephra
large pieces tend to fall near the volcano where they can cause injury or death (as well as damage structures). The smaller pieces (ash) can travel for thousands of kilometres
128
ash falls
can be very disruptive as it covers everything causing poor visibility and slippery roads. Roofs may collapse under the weight and engines may get clogged up and stop working.
129
gas eruptions
Magma (lava that hasn’t reached the Earth’s surface) contains dissolved gases that are released into the atmosphere during eruptions.
Once the gases are in the air they can travel for thousands of kilometres.
130
what gases do gas eruptions from volcanoes include
These gases include water vapour (around 80%), carbon dioxide and sulphur dioxide.
131
are gas eruptions dangerous
Some gases can be potential hazardous to people, animals and structures.
132
secondary hazards of volcanoes
lahars
jokulhaulp
133
what are lahars
masses of rock, mud and water that travel quickly down the sides (flanks) of a volcano.
134
how big are lahars
They vary in size and speed. The largest can be hundreds of metres wide and can flow at tens of metres per second (too fast to outrun!)
135
how are lahars caused
They are caused when an eruption quickly melts snow and ice OR when heavy rainfall has occurred either during or after an eruption and has eroded rocks and soil, causing it to become lose and surge downslope.
136
what are jokulhaulps
a glacial outburst flood
can suddenly release large amounts of water, rock, gravel and ice that can be extremely dangerous as they can flood and damage land and structures
137
how are jokulhaulps caused
These are when the heat of a volcano melts the snow and ice in a glacier causing heavy and sudden floods.
138
how do scientists accurately predict volcanic eruptions
Scientists use equipment (GPS and satellite-based radar) placed on and around a volcano to monitor the signs
139
how are small earthquakes detected
as magma rises it breaks rock, causing small earthquake, which can be detected on seismograms.
140
what changes are monitored by scientists in volcanoes
Changes to the surface of the volcano – magma builds pressure, causing the surface of the volcano to swell.
Changes to the ‘tilt’ of a volcano – moving magma inside can change the slope angle or ‘tilt’.
141
how are tsnumais caused
Most tsunamis are caused by underwater earthquakes, a small number are produced by underwater landslides, or by meteor/asteroid strikes.
142
how is the water column dusplaced during a tsunami
Energy released during the earthquake causes the sea floor to uplift
143
what is a water column
the area of seawater from the surface to the sea floor
144
how fast can tsunamis move
can move fast – up to 500 mph
145
what is the vacuum effect in tsunamis
When the wave crest reaches the shore, it first produces a vacuum effect – it sucks the water back out to sea, exposing a large amount of the sea floor (a warning sign of a tsunami).
146
why is there no way to predict tsunamis before they occur
Since most tsunamis are caused by submarine earthquakes (and we can’t predict them), there is no way to predict tsunamis before they occur.
147
where are early warning systems for tsunamis in place
the indian ocean
pacific ocean
148
how do warning systems for tsunamis work
use seismic sensors to detect submarine earthquakes, however because not all submarine earthquakes causes tsunamis, additional equipment is used.
149
what does DART stand for
Deep-ocean Assessment and Reporting of Tsunami.
150
how does Dart monitor changes in sea level and pressure
uses seabed sensors and surface buoys
151
how does DART work
When waves are detected, the system sends the information via a satellite to tsunami warning stations.
These stations then analyse the data to estimate the size and direction of the tsunami, before informing the areas at risk.
152
pros of computer modelling to monitor tsunamis
Can save lives
Information can be reviewed regularly due to multiple sensors and sea surface buoys.
153
cons of computer modelling to monitor tsnumais
If the equipment is faulty then it will result in inaccurate data.
If there is a shallow earthquake, equipment can become damaged
154
According to the Centre for Research on the Epidemiology of Disasters (CRED), how many people need to be affected for a hazard to become a disaster?
100
155
Up to what speed can tsunamis travel?
500mph
156
How are tsunamis caused?
submarine earthquakes
157
what is a hazard
‘A perceived natural/geophysical event that has the potential to threaten both life and property’
158
what is a disaster
The realisation of a hazard, when it ‘causes a significant impact on vulnerable population
159
when did the Centre for Research on the Epidemiology of Disasters (CRED) state that a hazard becomes as disaster
10 or more people are killed and/or
100 or more people are affected
160
what model looked at hazard vs disaster
Deggs model
161
the hazard risk formula
risk= hazard x vunerability divided by capacity to cope
162
what does the level of risk of a hazard depend on
combination of factors:
Some directly linked to the hazard itself e.g. magnitude, duration and time of day.
Human factors – which determine vulnerability and capacity to cope.
163
resilience
The ability to protect lives, livelihoods and infrastructure from destruction, and to restore areas after a natural hazard has occurred.
164
human factors determining disasters can be divided into what categories
social
economic
environmental
political
165
social factors that can determine disasters
communities with poor healthcare
these communities suffer more disease and are less able to cope with and recover from a hazard such as a flood
166
political factors that can determine disasters
quality of communication systems
affects the ability to inform people of a hazard in advance and to coordinate rescue and recovery efforts
167
environmenmtal factors that can determine disasters
rapid urbanisation creates a need for more housing
a increase in demand for housing means houses are built quickly which means the quality is poor
168
how does failure of development impact vunerability
Less-developed countries are generally more vulnerable to hazard events because they tend to have other, more pressing problems (such as poverty and disease), which means that they spend less money on disaster preparation.
169
age and resilience
Age is a significant factor in people’s resilience, with children and the elderly likely to suffer much more from a range of hazards.
170
what % of the worlds population aged 60 and over live in less-developed regions
66%
expected to rise to 79% by 2050
171
case studies for age and resilience
Myanmar
Japan
172
Myanmar hazard exposure score
Myanmar has a significantly high natural hazard component due to the potential for tsunami and earthquakes ( as well as floods and storms).
173
Japan hazard exposure score
Japan is subject to a range of natural hazards and is highly exposed.
174
Myanmar vunerability
Moderate risk though a relatively low score – there have been few natural shocks in recent years.
175
Japan vulnerability
Vulnerability is high compared to other wealthy nations due to the ageing population, but it is still low risk.
176
myanmar coping capacity
Poor coping capacity; low level of internet/mobile phone access for older people; education is poor.
177
Japan coping capacity
Coping capacity is good; the elderly tend to be educated, have high internet connectivity, effective government and low gender inequality.
178
Myanmar overall risk
Myanmar is ranked 7th out 190 nations, which means that the disaster risk to elderly citizens is very high
179
Japan overall risk
Although Japan is highly exposed to hazards, it is ranked 133rd out of 190 nations thanks to its strong coping capacity and lower levels of vulnerability.
180
what does the Pressure and Release model do
used by governments and organisations to work out how vulnerable a country is
it looks at the underlying cause of a disaster
It’s based on the idea that a disaster happens when two opposing forces interact: on one side are the processes that create vulnerability and on the other, the hazard itself.
181
name three countries located on tectonic plate margins which make them vunerable to earthquakes
Haiti
China
Japan
182
what factors influence the vulnerability and resilience of a country
development
governance
geographical
183
development factors
education
housing
healthcare
income opportunities
184
governance factors
local and national
185
geographical factors
population density
isolation/accesibility
degree of urbanisation
186
what is Spearmans rank
a statistical test that examines the degree of which two data sets are correlated, in this case whether the greater the magnitude results in a greater loss of life.
187
what does the calculation from spearmans rank show us
The calculation gives us a numerical value on the degree of the correlation – between 1 and minus 1.
1 = perfect positive correlation
0 = no correlation
-1 = perfect negative correlation
188
how are earthquakes and volcanoes measured
A number of tolls and techniques can be used to measure the magnitude and intensity of tectonic hazards.
Magnitude and intensity are objective (uses the facts); numerical descriptors of the size and intensity of tectonic events are usually based on measurements recorded from instrumentation.
189
methods of measuring earthquakes and volcanoes
richter scale
mercalli scale
moment magnitude scale
volcanic explosivity index
190
richter scale
This is used to measure the amplitude (height) of the waves produced by an earthquake.
A scale of 0-9 is used, with measurements of 9 being the highest.
The Richter Scale is an absolute scale; wherever an earthquake is recorded, it will measure the same on the Richter Scale.
191
mercalli scale
This scale measures the experienced impacts of an earthquake on a scale of I-XII (roman numerals).
It is a relative scale, because different people experience different amounts of shaking in different places.
It is based on a series of key responses, such as people awakening, the movement of furniture and damage to structure etc.
192
moment magnitude scale (MMS)
This scale is a modern measure used by seismologists to describe earthquakes in terms of energy released
The magnitude is based on the ‘seismic moment’, which is calculated from: the amount of slip on the fault; the area affected; and an Earth-rigidity factor.
The USGS (US Geological Survey) uses MMS to estimate magnitudes for all large earthquakes
193
volcanic explosivity index (VEI)
A relative measure of the explosiveness of a volcanic eruption, which is calculated from the volume of products (ejecta), height of the eruption cloud and qualitative observations
Like the Richter Scale and MMS, the VEI is logarithmic: an increase if one index indicates an eruption that is ten times as powerful
194
what are tectonic hazard profiles
A hazard profile compares the physical processes that all hazards share
They can be used to analyse and assess the same hazards which take place in contrasting locations or at different times
195
what categories do tectonic hazard profiles look at
magnitude
speed of onset
duration
areal extent
spatial predictabiltiy
frequency
196
advantages of using hazard profiles
help governments and other organisations develop disaster plans
It can show a single hazard or multiple hazards – allowing comparisons to be made.
197
disadvantages of using hazard profiles
Comparing different hazards may not be reliable as they have different impacts
198
what has happened to the total number of reported natural disasters since 1960
risen dramatically
198
why has the number of natural disasters since 190 increased
improvements in monitoring/recording events has contributed to a rise in reported events.
Improvements in communications technology – in 1960 transatlantic satellite communication didn’t exist! In contrast, the world watched live coverage of the Japanese tsunami in 2011.
The global population has increased – it was less than 3 billion in 1960. More people now occupy more hazardous space (e.g. by rivers and coasts).
An increase in occupied living space – more concrete and other impermeable building materials (often on or close to flood plains).
199
current trends for natural disasters
Developed countries are better able to cope with hazardous events.
Economic development can influence the number of people killed by a disaster – but also it’s financial cost.
Overall, the number of deaths from disasters globally is falling.
However between 1994 – 2013, the average number of people dying per disaster was over three times higher in developing countries (322 deaths) than in developed countries (105).
The financial cost is rising. In the 1990s, the economic cost of natural disasters averaged US$20 billion per year, increasing to about US$100 billion per year between 2000-2010.
200
how much did natural disasters cost in the 1990s
conomic cost of natural disasters averaged US$20 billion per year, increasing to about US$100 billion per year between 2000-2010.
201
what factors affect data reliability
Differences in the definitions of some key terms such as ‘disaster’ or ‘damage.
When a disaster strikes the immediate focus is rescue efforts.
No single organisation is responsible for collecting data, therefore methods may vary.
Remote areas affected can be difficult to access, therefore deaths and damage can be under-reported.
Declaration of disaster deaths and casualties may be subject to political bias – e.g. the impact of the 2004 Boxing Day Tsunami were later down played by the Thai government for fear it would affect the tourist industry.
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key charachteristics of tectonic mega-disasters
Usually large-scale disasters either spatially or in terms of their economic/social impact.
Pose serious problems for effective management to minimise their impact.
Their scale of impact may mean that communities, but usually governments as well, require international support in the immediate and long-term aftermath
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what is a multiple hazrad zone/disaster hotspot
are places where a number of physical hazards combine to create an increased level of risk for the country and its population.
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what has happened to the number oh hazards in multiple hazard zones
number of tectonic hazards has remained the same over recorded history, but the number of hydrometeorological hazard events have increased
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why are the number of people affected by multiple hazard zones increasing
population increases and urbanisation rates increasing, the number of people being affected by these events is also increasing, which results in a higher economic cost.
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when are the impacts of multiple hazard zones made worse
often made worse if the population of that country is vulnerable (wealth/GDP, population density etc)
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what is the difference between hazard forecasting and prediction
Prediction is stating when an earthquake is going to take place.
Forecasting is giving a timeframe of when an earthquake could happen e.g. years to decades.
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what is hazard prediction and forecasting for earthquakes based on
This is based on a statistical likelihood of an event happening at a particular location
These forecasts are based on data and evidence gathered through global seismic monitoring networks, as well as historical records
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what are precursors
warning signs which can identify a characteristic pattern of seismic activity (foreshocks) or some other physical, chemical or biological change (such as animal behaviours or changes in radon emissions).
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what must predictions do to be useful
to be useful – that is, to enable evacuation of affected areas – they must be highly accurate, both spatially and temporally. This at present is impossible and many geoscientists do not believe that there is a realistic prospect of this happening in the foreseeable future
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how accurate is forecasting and prediction for volcanoes
can be predicted with some accuracy
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how can volcanoes be predicted
placing equipment on a volcano as well as using remote equipment (such as GPS and satellite-based radar), scientists can monitor a volcano for signs that it might erupt, such as:
small earthquakes – rising magma breaks rock, causing small quakes
changes of the shape of the surface – as it pushes upwards, the magma builds pressure causing the surface to swell
changes to the ‘tilt’ of the volcano – magma movement inside the volcano can change the slope angle or tilt.
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why is forecasting important
It can encourage governments to enforce better building regulations in areas of high stress, or create improved evacuation procedures in areas of highest risk
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what is hazard management
is a process in which governments and other organisations work together to protect people from the natural hazards that threaten their communities
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what model looks at hazard management
the hazard management cycle
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what are the 4 stages of the hazard management cycle
mitigation (prevention)
preparedness
response
recovery
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what is the focus of mitigation
identifying potential natural hazards and taking steps to reduce their impact
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what is the main aim of mitigation
preventing hazard events or minimising their impacts
to reduce the loss of life and property (by making communities less vulnerable)
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actions of mitigation
zoning and land use planning
developing and enforcing building codes
building protective structures(such as tsunami sea defence walls)
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when does mitigation take place
before and after hazard events
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focus of preparedness
minimising loss of life and property and facilitating the response and recovery phases
many activities are developed and implemented by emergency planners in both governments and aid organisations
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what is preparedness
preparing to deal with a hazard event
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actions of preparedness
developing preparedness plans
developing early warning systems
creating evacuation routes
stockpiling aid equipment and supplies
raising public awareness (holding earthquake drills)
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when does preparedness take place
before hazard events
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what is the focus of response
coping with disaster
the main aims are to save lives, protect property, make the affected areas safe and reduce economic losses
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what is the aim of response
responding effectively to a hazard event
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what actions are involved in response
search and rescue efforts
evacuating people where needed
restoring critical infrastructure (power and water supplies)
ensuring that critical services continue (medical care and law enforcement)
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when does response take place
during hazard events
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what is the focus of short term recovery
focuses on peoples immediate needs, so it overlaps with the response phase- activities may last for weeks altho called short term
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focus of long term recovery
involves some of the same actions as short term but may continue for months or years
includes taking steps to reduce future vulnerability which overlaps the mitigation phase
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aim of recovery
getting back to normal
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short term recovery actions
providing essential health and safety services
restoring permanent power and water supplies
re establishing transportation routes
providing food and temporary shelter
organising financial assistance to help people rebuild their lives
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actions involved in long term recovery
rebuilding homes and other structures
repairing and rebuilding infrastructure
reopening businesses and schools
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when does recovery take place
after hazard events
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why might hazard management not always work
event is bigger than anticipated
unexpected secondary impacts
regulations are ignored (corruption eg China)
other hazards interfere (multiple hazard zones)
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what does the Parks model show
The Park hazard-response curve is a model that shows how a country or region might respond after a hazard event.
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what can the Parks model be used to compare
can be used to directly compare how areas at different levels of development might recover from a hazard event
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key points of the Parks model
The impacts of a hazard event change over time – depending on factors such as the size of the hazard, the development level of the areas affected and the amount of aid received.
All hazard events have different impacts, so their curves are different.
Recovery depends on wealth, so wealthier (developed) countries will recover much faster
In hazard events that affect a number of countries (e.g. the Indian Ocean tsunami in 2004), each country has its own curve.
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hazard mitigation
strategies meant to avoid, delay or prevent hazard events
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hazard adaption
strategies designed to reduce the impacts of hazard events
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mitigation strategies
land use zoning
diverting lava flows
GIS mapping
hazard resistant design and engineering defences
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land use zoning
local government planners regulate how land in a community may be used
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diverting lava flows
methods used to attempt to divert lava flows away from people and communities
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GIS mapping
can be used in all stages of the hazard management cycle e.g. identifying evacuation routes
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Hazard-resistant design and engineering defences
buildings designed to withstand earthquakes and shaking
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adaption strategies
high tech monitoring
crisis mapping
modelling hazard impact
public education
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high tech monitoring
including early warning systems, mobile phones and satellite
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crisis mapping
crowd-sourced information is used to create a live map interactive map of areas struck by a disaster
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modelling hazard impact
computer models allow scientists to predict the impacts of hazard events and compare different scenarios.
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public education
good education and public awareness can help reduce the vulnerability and prevent hazards from becoming disasters.
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During the recovery and response stages of the hazard-management cycle what do efforts focus on
on helping communities cope with personal, social and economic loss
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key players in managing loss
Aid donors (emergency, short term, long term aid)
Non-governmental organisations (NGOs)
Insurance
Communities
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