Primary and Secondary Hazards of Earthquakes & Impacts Thereof

Question 1

What is ground movement as a hazard?

Answer 1

Surface seismic wavs cause the most severe hazards to humans; buildings collapse, gas and water pipes severed.

Question 2

Near the epicentre, which waves do the most damage?

Answer 2

S and P. Unconsolidated sediment can amplify shaking and differential damage can happen as a result of different surface materials, such as San Francisco topography.

Question 3

In the 1989 Loma Prieta earthquake, what was the impact of ground shaking?

Answer 3

It was a MM 7.1 with 98% of economic loss due to ground shaking.
41 of the 67 dead were due to a freeway which collapsed due to its construction on mud.

Question 4

Which types of building are most dangerous?

Answer 4

Poorly buik, unreinforced structures with heavy tiled roofs are most dangerous.

Question 5

What happened in the 1988 Armenia earthquake?

Answer 5

88% of buildings destroyed within 5km, but 95% destroyed within 35km due to soft foundations and no earthquake proofing.

Question 6

What is liquefaction?

Answer 6

Loose sediments can become water-saturated and act as a fluid, increasing pore water pressures. Poorly compacted sands and silts below 10 metres the surface are most affected.
This caused buildings to collapse in the Christchurch NZ earthquake.

Question 7

How are landslides, rockslides and avalanches secondary hazards?

Answer 7

Severe ground shaking causes slopes to weaken and fail, causing slides. Especially dangerous in mountainous areas (48 dead on Mt Everest in Nepal quake). Post-earthquake landslide risk varies with topography, rainfall, soil and forestry.

Question 8

What happened in the Peru 1970 earthquake?

Answer 8

Rock avalanche formed a 50m high wave at 70 m/s, killing 18,000 in 4 minutes.

Question 9

How are tsunamis formed?

Answer 9

They are the most destructive secondary hazard. Generated at subduction margins, and need a 6< earthquake with vertical displacement, causing ocean waves that spread out and take debris towards land, gaming power in the process.

Question 10

How many have died from tsunamis since 1900?

Answer 10

500,000, with over half of that as a result of the 2004 Indian Ocean tsunami.

Question 11

What are the 4 factors in severity of an earthquake?

Answer 11

Wave energy, water depth, coastline and topography.

Question 12

What are primary effects?

Answer 12

Immediate consequences, damage from shaking and deaths from people hit by tiles. From 2000-2017, over 800,000 died to primary effects.

Question 13

What changes in environment can result from landslides and tsunamis?

Answer 13

Land can be uplifted or subside. The 1976 Alaska earthquake saw some areas uplifted by 9 metres.

Question 14

What are secondary effects?

Answer 14

Effects in the days following, such as air pollution from fires or combustion from leaking gas mains. Contamination from sewage resulted in 739,000 cholera cases in the 2010 Haiti earthquake.
Physical infrastructure can be destroyed.

Question 15

What does recovery mainly depend on?

Answer 15

The economic status of an area, in a HIC there are management plans in place and financial contingency plans allocated.

Question 16

What are the social secondary consequences?

Answer 16

Factories close, leading to a loss in wages, productivity, future orders, exports and unemployment.
Communities are threatened by hunger, disease and social disorder

Question 17

How are rural earthquakes damaging to the environment?

Answer 17

Farmland and crops damaged and landslides prevent transport of goods.

Question 18

How are urban earthquakes damaging to the built environment?

Answer 18

High density of buildings and value of infrastructure amplify damage of earthquake.
Destroyed buildings leave large areas of derelict land and uncollected refuse and decomposing organic material results in infestation.

Question 19

What are the statistics on the 2015 Nepal earthquake?

Answer 19

7.8 Richter, and only had 8964 dead since most were out of the village working. 3.5m dead in long-term effects. $10 billion damage.
Avalanche on Everest killed 21.
By 2017, only 5% rebuilt.

Question 20

What is the Degg Model?

Answer 20

‘A disaster only occurs if hazardous processes interact with a vulnerable population, if they are separate then there is no damage’.

Question 21

What is risk defined as?

Answer 21

The probability of a hazard occurring and creating loss of lives and livelihoods.

Question 22

Why do some people consciously place themselves at risk?

Answer 22

Unpredictability of hazards - Osaka eruption 48 dead in unexpected eruption.
Changing risk over time.
Lack of alternative locations to live
Economic benefits
Optimistic perception of hazard risk.

Question 23

What is vulnerability?

Answer 23

A high risk of hazard combined with an inability to cope. This is the degree of resistance of a social system, dependant on reliability of local management and governance.

Question 24

What is the Risk Equation?

Answer 24

Frequency/magnitude of hazard X vulnerability divided by capacity of population to cope.

Question 25

What are the 3 parts that capacity to cope splits into in the Pressure-and-Release PAR model?

Answer 25

Unsafe conditions
Dynamic Pressures
Root causes.

Question 26

How are unsafe conditions part of capacity to cope in the PAR?

Answer 26

Dangerous location
Unprotected buildings
Weak economy
Lack of disaster preparedness
Prevalence of hunger and diseas

Question 27

How are dynamic pressures part of capacity to cope in the PAR?

Answer 27

Lack of training, skills and food
Rapid population change
Rapid urbanisation
Debt repayment issues.
Over-exploitation of resources.

Question 28

How are root causes part of capacity to cope in the PAR?

Answer 28

Limited resources to power, structures and resources.
Failing political, social and economic systems.

Question 29

What is the PAR?

Answer 29

Pressure-And-Release system, working that earthquakes are caused by a sudden release of energy from a buildup of pressure.

Question 30

Which two types of impact usually come hand in hand?

Answer 30

Severe economic impact usually results in a higher social impact.

Question 31

What was the social and economic impact of the 1999 Turkey earthquake?

Answer 31

7.4 Richter, 17,225 dead and $12 billion USD damage.

Question 32

What does PAR argue about the root cause of disaster?

Answer 32

They result in unsafe conditions, but come from the poorly enforced or poorly implicated economic and political systems of LICs.

Question 33

What does PAR argue about why the most vulnerable people live in the most hazardous environments?

Answer 33

Malnutrition, disease, armed conflict, poor governance and lack of education all exist in poor communities and therefore makes them more vulnerable.

Question 34

How do economic factors act as drivers of disaster and vulnerability?

Answer 34

Vulnerability is closely associated with absolute poverty and the wealth gap. The least-developed countries lack money to invest in education, social services, infrastructure and technology which would help in disaster response.
Economic growth increases economic assets and therefore increases risk.

Question 35

How do technological factors act as drivers of disaster and vulnerability?

Answer 35

Technological solutions help mitigate disasters, create earthquake-proof designs, prevention, protection and monitoring of tectonic activity.
Wealthy countries have an over-reliance on technological aid so if the hazard affects tech systems then they can suffer even further in the aftermath.

Question 36

How do social factors act as drivers of disaster and vulnerability?

Answer 36

Demographic growth in LICs means that many live in dense, unsafe areas.
Increasingly aged population increases vulnerability with a a lack of resilience and mobility.
Disadvantaged people more likely to die and suffer psychological trauma.
In 2005 Kashmir, badly built schools led to disproportionate child deaths.

Question 37

How do political factors act as drivers of disaster and vulnerability?

Answer 37

Lack of strong government procedures produces weak organisation in response.
Lack of financial institutions inhibits disaster mitigation and emergency post-disaster recovery.
2015 Nepal had building standard ignored and only 12 fire engines, as a result of neglect and poor quality governance over many years.

Question 38

How do geographical factors act as drivers of disaster and vulnerability?

Answer 38

Increasing urbanisation - poorly sited squatter settlements creates hazard risk and exposure.
Relief, rescue and recovery difficult in Kashmir due to isolation, temperature and it being a war frontier.
Multi-hazard hotspots amplify damage.