Unit 3 Flashcards
(98 cards)
1
Q
What % of earthquakes occur along plate boundaries?
A
85%
2
Q
What is meant by the focus of an earthquake?
A
the point of fracture within the crust
3
Q
What is meant by the epicentre of an earthquake?
A
the point on the Earth’s surface located directly above the focus
4
Q
Where do seismic waves occur and what are they recorded by?
A
when a fracture occurs seismic waves radiate outward from the focus
- recorded on a seismograph by seismograms
5
Q
How can the epicentre of an earthquake be located?
A
the time at which an earthquake waves is recorded at different seismographs can be used to locate the epicentre
6
Q
What is meant by the magnitude of an earthquake?
A
refers to the amplitude of the shock waves recorded on a seismograph
7
Q
How is the magnitude of an earthquake recorded?
A
Richter Scale
8
Q
What is the range of the Richter Scale?
A
ranges from 1 - 9 (1 being undetectable by humans 8.5 is total destruction
9
Q
How is the intensity of an earthquake determined?
A
by the degree of shaking, which is measured by the Modified Mercalli Scale (biased and based on qual data = subjective
10
Q
What is meant by a risk?
A
the likelihood of a hazard occurring
10
Q
What is meant by a hazard?
A
something that causes harm/damage to people, infrastructure and environment
11
Q
What are the three types of waves caused by an earthquake?
A
P waves,
Swaves,
Surface waves (Love and Rayleigh waves)
12
Q
What are P waves?
A
Push waves
- compressional waves, where energy is transferred
- first to hit after an earthquake
13
Q
What are S waves?
A
Secondary/Shear waves
- move side to side, slower than P waves, arrive later to the surface
- these are perpendicular to the motion of travel
14
Q
What are Surface Waves?
A
- Slower but longer
- mix of P and S waves
- most destructive waves
15
Q
What are some of the factors that affect the severity of an earthquake?
A
- geology
- poverty
- poor governance
16
Q
What type of hazard is liquefaction?
A
Secondary hazard
17
Q
What is liquefaction?
A
- sediments shaken by seismic waves
- seismic waves amplify in soft unconsolidated sediments
- water saturates sediments compact
- water forced upwards
- water and sediment erupt onto the surface
- softened ground surface causes buildings to subside
18
Q
How does the geology impact on the risk of liquefaction?
A
hard sediment = less risk
soft sediment = more risk, after earthquake ground solidifies again
19
Q
What type of hazard is a tsunami?
A
Secondary Hazard, of earthquakes
20
Q
What is meant by a tsunami?
A
is a series of powerful ocean waves caused by the displacement of a large volume of water
21
Q
What are the two case studies of earthquakes where there were tsunami’s?
A
- Japan 2011
- Indian Ocean region, Boxing Day 2004
22
Q
What are the three main causes of tsunami’s?
A
- underwater landslide
- Earthquakes - tectonic fault movements, can shift sea bed
- Volcanoes, sides of them collapse
23
Q
How can earthquakes cause tsunami’s, and what type of plate boundary are they associated with?
A
plate boundary = oceanic, continental crust convergent margin
the subduction causes the continental crust to displace water above, as it pushes over the oceanic plate boundary
24
How fast can tsunami waves pass through deep water ocean?
5 miles per second
25
When the tsunami approaches the shore, why does the wave height increase?
when it reaches shallow water, the height increases as the speed of flow slows, allowing the water to accumulate
26
What was the magnitude of the earthquake in Japan 2011?
mag. 9 earthquake in the Pacific ocean
27
What was the size of the tsunami caused by the earthquake in Japan 2011?
flooded 200 sq miles of coast land
28
What was the estimated size of the tsunami waves, after the 2011 Japan earthquake?
38m
29
What was the economic cost of the tsunami and earthquake of 2011 Japan?
$360 billion, a lot of damage
(compared to Hurricane Katrina = $250 billion)
30
How many died due to earthquake in Japan 2011, what % were from drowning during the tsunami?
20,000 people, more than 90% of death were from drowning
31
What was a severe impact of the tsunami in Japan 2011?
failure of the nuclear power station in Fukushima, had severe long lasting effects
32
What was the magnitude of the earthquake in the Indian Ocean in 2004?
Mag 9.1, earthquake of the coast Indonesia
33
How tall were the tsunami waves in the Indian ocean earthquake 2004?
topped 30m
34
What were the social impacts of the 2004 Indian ocean earthquake/tsunami?
nearly 230,000 died
left 2 million people homeless
35
How many countries where effected by the events in the Indian ocean 2004, and which was the worst affected?
13 countries effected, the worst being Indonesia
36
What was the warning system like for the tsunami in the Indian Ocean in 2004?
They had no early warning system, only released when they saw it coming
37
What type of hazard is a landslide?
Secondary hazard
38
How does the amount of ground shaking increase the risk of a landslide?
- causes sediment to collapse, more shaking causes more movement in sediment
39
How does the steepness of slop increase the risk of a landslide?
increased speed of landslide (gravity)
40
How does the type of rock increase the risk of a landslide?
softer = easier for sliding
sedimentary rock = weaker
41
How does the saturation of the soil increase the risk of a landslide?
more saturated = stronger, because it offers easier movement
42
How does land use increase the risk of a landslide?
agriculture or urbanised = more pressure on the ground
whereas trees and their roots hold the soil intact
43
What is an example of where an earthquake triggered a landslide in an NIC?
2008 Wenchuan earthquake in China
44
What was the magnitude of the earthquake in Wenchuan in China?
7.9
45
How many landslide and mud flows occurred during/after the Wenchuan China earthquake?
80,000
46
How many people died from one single mudflow in Wenchuan China?
200 people
47
What is the case study for an earthquake in an LEDC where there were landslides?
2005 Pakistan Earthquake
48
What was the magnitude of the 2005 Pakistan earthquake?
7.6 magnitude
49
How many people died during the 2005 Pakistan earthquake?
85,000
50
How many landslides were triggered in Pakistan 2005 earthquake?
2500 landslides
51
How many deaths were caused directly because of landslides in Pakistan 2005 earthquake?
26,500
52
How many were left homeless due to the effects of the 2005 Pakistan Earthquake?
3.5 million ppl left homeless
53
What were the impacts of the landslides in 2005 Pakistan earthquake?
blocked roads, destroyed telephone lines resulting in delayed responses by search & rescue and medical teams
54
What are the two case studies for the earthquakes in countries with contrasting wealth?
USA (Loma Prieta, California) vs Haiti
55
What was the date of the Loma Prieta earthquake?
5;07 pm 17th October 1989
56
What was the date of the Haiti earthquake?
4;53 pm 12th Jan 2010
57
What was the magnitude of the Loma Prieta earthquake?
6.9 RS
58
What was the magnitude of the Haiti earthquake?
7.2 RS
59
What type of plate boundary did both the Loma Prieta and Haiti earthquake occur on?
A conservative plate boundary
60
What was the population size (at the time) of both Loma Prieta and Haiti in a 50mile radius of the epicentre?
over 2 million for both
61
What was the death toll in Loma Prieta earthquake compared to the Haiti earthquake?
USA= 63
Haiti = over 220,000
62
How many were injured in the USA earthquake compared to Haiti?
USA = 3757
Haiti = over 300,000
63
What was the number of homes damaged in the USA earthquake compared to the one in Haiti?
USA= 12,000
Haiti = OVER 100,000
64
What was the economic damage of the earthquakes in the USA and Haiti?
USA = $6.8 billion (0.12% of their GDP)
Haiti = $7.8 billion (120% of their GDP)
1000x greater than USA
65
What was the distance of the focus for the Loma Prieta earthquake?
Shallow focus of 11 miles, caused by movement along the conservative San Andreas Fault
66
What was the secondary hazards of the Loma Prieta earthquake?
Liquefaction and landslides
67
What were the social impacts of the liquefaction that occurred in Loma Prieta?
42 of the 63 deaths occurred due to the collapse of the 2 level Cypress Freeway in Oakland, subject to liquefaction
68
What where the economic impacts of the Liquefaction in Loma Prieta?
The collapse of the 2.5km section of the Freeway caused disruption, area with 170,000 vehicles travelling everyday
- took 9 years and $1.2 billion to rebuild to a higher standard aseismic design
69
What was the worst affected area, due to the liquefaction in the Loma Prieta earthquake?
San Francisco with the worst affected area being the Marina District
The district was built on landfill made with a mixture of sand, rubble and other materials containing a high percentage of ground water
70
How many landslides occurred during the Loma Prieta earthquake?
more than 1000
71
Where did most of the landslides and rockfalls occur during/after the Loma Prieta earthquake?
around the epicentre zone in the Santa Cruz Mountains
One slide on the State Highway 17 disrupted traffic for 1 month
72
What is the future risk of a high magnitude earthquake hitting California in the near future?
>99% of a high mag affecting Cali
>70% affecting San Francisco between 2014 and 2034
73
How many people in the state of California have earthquake insurance?
1 in 10 Californians (increases their vulnerability)
74
To what extent is San Francisco prepared for the next earthquake?
- most of the densely populated areas are located on landfill
- not all buildings are earthquake resistant
- buildings since 2018, been built to an aseismic standard, which are earthquake resistant
- lots of peoples homes have garages underneath = open space = increased vulnerability
75
Where is Haiti located?
within the Caribbean, sits on a conservative (transform) plate boundary
76
What is the GDP of Haiti compared to the UK?
Haiti is one of the poorest nations in the Northern Hemisphere
Current GDP: $3300
UK GDP: $55000
77
What were the immediate short term impacts of the Haiti earthquake?
in capital city 80% of buildings collapsed/were seriously damaged, including the presidential palace
78
What were the 4 human (quality of gov) factors contributing to the disaster?
- building design
- land use planning
- community preparedness
- emergency/relief services
(they were all shit btw but you'll find out)
79
What were the building designs like in Haiti, before the earthquake?
86% of the pop in Port Au Prince were living in tightly packed slum conditions
housing had no aseismic design
modern concrete structures were also built using cheap construction techniques, not enough enforcing steel rods
80
What was the land use planning like in Haiti before the earthquake?
no planning done to take into account earthquakes
crowded conditions meant that roads were covered in rubble, hindered search and rescue
built on soft sediments
81
What was the community preparedness like before the earthquake in Haiti?
80% of the schools were of poor quality
literacy levels were poor
most people received no earthquake training, no drills in place and didn't know what to do
82
What were the emergency and relief services like for the earthquake in Haiti?
many of the hospitals were destroyed or badly affected by the earthquake
- the emergency services were not trained or resourced to deal with earthquake
- the airport damage, meant emergency rescue and flights were unable to land
- liquefaction destroyed the Port area, very hard for initial emergency relief
83
What % of gov and administrative buildings were destroyed in the Haiti earthquake? (social impact)
Many gov officials killed as 60% of the buildings collapsed, there were few people left to organise and manage relief efforts
84
How many schools in Port au Prince and the rest of Haiti were destroyed during the Haiti earthquake? (social impact)
80% of the schools in Port au Prince
60% in the wider area of Haiti
85
Where were the homeless population moved to after the Haiti earthquake? (social impact)
were moved to 1100 temporary camps with few facilities
86
What were some of the other social impacts of the Haiti earthquake in terms of disease and deaths?
bodies were left on the streets or rubble, this lead to disease outbreaks such as cholera leading to an additional 12,000 deaths
- city jail was destroyed and many prisoners escaped potentially leading to security and crime risks
87
What were the economic impacts of the Haiti earthquake?
Total economic cost was estimated at $7.8 billion
damage and losses were equivalent to 120% of the countries GDP in 2009-
rebuilding of homes cost an estimated $2.3 billion
- unemployment rose 76% of households
88
What were the positive aid income of the Haiti earthquake?
- $3.5 billion was given in Foreign aid following the disaster
- the financial contribution of the EU as a whole totaled $330 million
- World Bank waivered Haiti's debt repayment for 5 years
- the government of USA, UK, Canada, Brazil and Italy sent over 1,000 military and disaster relief personel
89
Why has Haiti not recovered from the earthquake 10 years on?
- damage cost 120% of the countries GDP
- poverty
- only 48% of donations between 2010 and 2020 reached Haiti
- months after earthquake UN aid workers brought cholera causing an epidemic in Haiti
90
When did another earthquake hit Haiti?
August 2021, a mag 7.2
91
What were the impacts of the earthquake that hit Haiti in 2021?
1,300 initially killed
12,000 people injured - hospitals were struggling
- tropical storm hit hours later
- assassination of the president before the earthquake
- local gangs took over
92
How far was the epicentre from Haiti of the 2021 earthquake?
150km in the south west
93
When was the Turkey earthquake?
Feb 2023
94
What were the magnitudes of the 3 earthquakes that hit Turkey?
Rs ranging from 6.4 to 7.8
95
How many people were killed in Turkey in Feb 2023?
killed over 55,000 people
96
What was the impact of the Turkey earthquakes on infrastructure?
over 7,000 buildings collapsed
200,000 buildings were heavily damaged
97
Why did so many buildings suffer damage during the Turkey 2023 earthquakes?
- corrupt practices and flawed development = misspending of taxes that were meant for building earthquake resistant housing
- buildings weren't designed to withstand that level of shaking
