Tectonic Hazard Profiles (Edexcel A Level Geography)

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Bridgette Barrett

Written by: Bridgette Barrett

Reviewed by: Jenna Quinn

Tectonic Hazard Magnitude

Earthquake magnitude

  • Magnitude is the most common way to measure an earthquake

  • It measures the energy released at the source (focus)

    • The magnitude can be measured on different scales but the one which is reported on the news when a earthquake occurs is the Moment Magnitude Scale (MMS)

    • It is measured using seismographs

  • The MMS goes from 1 which are not felt by humans to 10

  • The MMS is a logarithmic scale which means that a 6 on the scale is a ten times increase in amplitude from a 5 

    • The energy release is 32 times greater

earthquake-magnitude
Magnitude of earthquakes

Earthquake intensity

  • The intensity of an earthquake is its impact on people, as well as the built and natural environments

  • The Modified Mercalli Intensity Scale is used to measure the intensity

  • The scale goes from I to XII

mercalli-scale
Modified Mercalli Intensity Scale

Examiner Tips and Tricks

Remember not to confuse magnitude and intensity.

Magnitude is the amount of energy released. Whereas intensity is severity of ground shaking at a particular place based on the effects on humans, buildings and the environment.

Measuring volcanic eruptions

  • Every eruption is unique some are gentle, others are hugely explosive

  • The Volcanic Explosivity Index (VEI) is used to measure the size of an eruption

  • This can not be measured on a scientific instrument so is calculated based on a series of measurements and observations

    • These include:

      • Height of material ejected into the atmosphere

      • Volume of material

      • Duration of the eruption

  • This is a logarithmic scale from 0-8 

887f2077-ef55-4c6d-8f85-361721f6d574
Volcanic Explosivity Index

Examiner Tips and Tricks

Magnitude is one of the key factors in the impact a hazard event has. However, it is important to remember that it is not the only factor - a magnitude 6.1 earthquake can have severe impacts in one area but the same magnitude in another area may have few impacts

Tectonic Hazard Characteristics

  • Hazard profiles can be used to compare tectonic hazard events

  • Hazard profiles usually include information about:

    • Magnitude

    • Speed of onset

    • Areal extent

    • Duration

    • Frequency

    • Spatial predictability

hazard-profile
Hazard profiles of tectonic hazards

Advantages 

  • Hazard profiles can be used to compare:

    • Different hazards

    • Same hazards with different processes - a volcano on a destructive boundary compared to one on a constructive boundary

    • Same hazards with different human vulnerabilities - an earthquake in a developed country compared to one in a developing country

  • They can also be used to plan for future events

  • They are useful when looking at one hazard such as an earthquake 

Disadvantages

  • Hazard profiles do have disadvantages:

    • Other factors may have a greater influence on the impact

    • They focus on physical factors when human factors may be the most important

    • Multi-hazard events are not easily represented on a hazard profile 

    • They are subjective 

Examiner Tips and Tricks

It is important to understand the advantages and disadvantages of using hazard profiles to compare hazards. You should be able to outline the advantages and disadvantages using real life examples. 

For example, you can compare magnitude of earthquakes on a hazard profile but the correlation between magnitude and impacts is not always straightforward due to other factors such as level of development. This can be seen in the comparison of Nepal (2015) and New Zealand (2016). They both experienced 7.8 magnitude earthquakes. However the number of deaths in Nepal was almost 9,000 whereas in New Zealand it was 2. Other factors such as population density had more impact on the number of deaths.

Tectonic Hazard Profiles

Earthquakes

Example

Profile Features

Social impacts

Economic impacts

Haiti (Developing) - 7.0 magnitude

  • Rapid onset

  • Damage focussed on Port au Prince but extended over much of south Haiti

  • Lasted 30 seconds

  • 220,000 deaths

  • 300,000 injured

  • 1.5 million homeless

  • 70% of buildings collapsed

  • Disease spread

  • Damages US$7.8 billion

  • Agriculture destroyed

  • Unemployment increased 

  • Exports decreased

Sulawesi, Indonesia (Emerging) - 7.5 magnitude

  • Rapid onset

  • Strongest shaking in Palu City

  • 4,340 deaths 

  • 10,670 injured

  • 206,500 homeless

  • Health risks

  • Damages US$1.3 billion

  • Tourism affected

  • Palu IV bridge collapsed

  • Infrastructure damage

Amatrice, Italy (Developed) 6.2 magnitude

  • Rapid onset

  • Strongest shaking felt in Amatrice - shaking felt by over 200,000 people

  • Lasted 20 seconds

  • 299 deaths 

  • 388 injured

  • 4,500 homeless

  • Damages over US$4 billion

  • Negative impact on tourism

  • Many agricultural buildings were damaged

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Bridgette Barrett

Author: Bridgette Barrett

Expertise: Geography Lead

After graduating with a degree in Geography, Bridgette completed a PGCE over 25 years ago. She later gained an MA Learning, Technology and Education from the University of Nottingham focussing on online learning. At a time when the study of geography has never been more important, Bridgette is passionate about creating content which supports students in achieving their potential in geography and builds their confidence.

Jenna Quinn

Author: Jenna Quinn

Expertise: Head of New Subjects

Jenna studied at Cardiff University before training to become a science teacher at the University of Bath specialising in Biology (although she loves teaching all three sciences at GCSE level!). Teaching is her passion, and with 10 years experience teaching across a wide range of specifications – from GCSE and A Level Biology in the UK to IGCSE and IB Biology internationally – she knows what is required to pass those Biology exams.