p7 Flashcards
affected the vulnerability and resilience
Development:
Education
Housing
Healthcare
Income Opportunities
Governance:
Local and national
Geographical Factors:
Population density Isolation/accessibility Degree of urbanisation
Spearman’s Rank
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.
The calculation gives us a numerical value on the degree of the correlation – between 1 and minus 1.
1 = perfect positive correlation 0= nocorrelation
-1 = perfect negative correlation
Measuring Earthquakes and Volcanoes
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.Richter Scale
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.
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
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.
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.
Tectonic Hazard Profiles
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.
Can you identify any advantages and disadvantages for using a hazard profile?
Advantages:
- Help governments and
other organisations
develop disaster plans. - It can show a single
hazard or multiple hazards – allowing comparisons to be made.
Can you identify any advantages and disadvantages for using a hazard profile?Disadvantages:
- Comparing different
hazards may not be reliable as they have different impacts.
How has the data changed?
Figure 1 shows that, since 1960, the total number of reported natural disasters has risen quite dramatically.
Figures 2-4 show that depending on the criteria that you use, the significance of geophysical disasters can change.
Why have these trends occurred?
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).
Current Trends
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.
Economic development can influence the number of people killed by a disaster – but also it’s financial cost.
E.g. Figure 4 the economic cost of the Japanese Tsunami in 2011 was around US$240 billion – whereas the death toll was 15,893.
Figure 2 – 230,000 Haitians died in the 2010 earthquake and had an economic cost of ‘just’ US$14 billion.
Factors affecting data reliability
Receiving accurate information about the frequency and impact of disasters is an important tool for governments, international organisations and aid agencies.
However, data collection is often incomplete/inaccurate:
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.
