Earthquake Engineering - Vol 2 | 29. Magnitude and Intensity Scales by Abraham | Learn Smarter
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29. Magnitude and Intensity Scales

29. Magnitude and Intensity Scales

Understanding the concepts of Magnitude and Intensity is essential for assessing and communicating the impacts of earthquakes. While Magnitude measures the energy released from the earthquake, Intensity focuses on the effects experienced at specific locations. These two measurements, despite their differences, are crucial for engineering, risk assessment, and improving the resilience of structures against seismic activities.

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  1. 29
    Magnitude And Intensity Scales

    This section outlines the concepts of magnitude and intensity in...

  2. 29.1
    Seismic Magnitude Scales

    Seismic magnitude scales quantify the energy released during earthquakes,...

  3. 29.1.1
    Richter Magnitude Scale (Local Magnitude, Ml)

    The Richter Magnitude Scale, developed by Charles F. Richter in 1935,...

  4. 29.1.2
    Body-Wave Magnitude (Mb)

    The Body-Wave Magnitude (Mb) is a measure of the energy released by an...

  5. 29.1.3
    Surface-Wave Magnitude (Ms)

    Surface-Wave Magnitude (Ms) quantifies the amplitude of surface waves...

  6. 29.1.4
    Moment Magnitude (Mw)

    Moment Magnitude (Mw) is a modern scale used to measure the total energy...

  7. 29.2
    Seismic Intensity Scales

    Seismic Intensity Scales measure the shaking and damage experienced at...

  8. 29.2.1
    Modified Mercalli Intensity (Mmi) Scale

    The Modified Mercalli Intensity (MMI) Scale measures the effects of an...

  9. 29.2.2
    European Macroseismic Scale (Ems-98)

    The European Macroseismic Scale (EMS-98) is designed to assess the impact of...

  10. 29.2.3
    Medvedev–sponheuer–karnik (Msk) Scale

    The MSK scale evaluates earthquake intensity focusing on human reactions,...

  11. 29.3
    Differences Between Magnitude And Intensity

    Magnitude measures the energy released by an earthquake, while Intensity...

  12. 29.4
    Isoseismal Maps

    Isoseismal maps display lines connecting points of equal earthquake...

  13. 29.5
    Correlation Between Magnitude And Intensity

    This section explores the empirical relationship between the magnitude of an...

  14. 29.6
    Engineering Implications Of Magnitude And Intensity

    This section emphasizes the engineering significance of magnitude and...

  15. 29.7
    Seismological Basis For Magnitude-Intensity Relationships

    This section explores the relationship between magnitude and intensity in...

  16. 29.7.1
    Empirical Relationships

    Empirical relationships connect earthquake intensity with magnitude through...

  17. 29.8
    Limitations And Sources Of Uncertainty

    This section outlines the limitations of magnitude and intensity scales used...

  18. 29.8.1
    Magnitude Scale Limitations

    This section highlights the limitations of magnitude scales in assessing...

  19. 29.8.2
    Intensity Scale Limitations

    This section discusses the limitations of intensity scales in measuring...

  20. 29.9
    Intensity Prediction Equations (Ipes)

    This section discusses Intensity Prediction Equations (IPEs), which estimate...

  21. 29.10
    Use Of Intensity In Seismic Hazard Assessment

    This section discusses the application of intensity measures in seismic...

  22. 29.11
    Contemporary Developments In Seismic Scaling

    This section discusses recent advancements in seismic scaling, particularly...

  23. 29.11.1
    Shakemap Systems

    ShakeMap Systems produce real-time intensity maps using instrumental data...

  24. 29.11.2
    Internet-Based Macroseismic Data Collection

    This section discusses the 'Did You Feel It?' program, which collects public...

  25. 29.12
    Case Studies On Magnitude And Intensity Application

    This section discusses significant case studies, including the 2001 Bhuj...

  26. 29.12.1
    2001 Bhuj Earthquake, India (Mw 7.7)

    The 2001 Bhuj earthquake in India, measuring Mw 7.7, caused severe ground...

  27. 29.12.2
    2015 Nepal Earthquake (Mw 7.8)

    The 2015 Nepal Earthquake, with a magnitude of 7.8, highlighted the role of...

  28. 29.13
    Summary Tables And Charts (Optional For Textbooks)

    This section discusses the importance of summary tables and charts in...

What we have learnt

  • Magnitude of an earthquake quantifies the energy released at its source, while intensity measures the shaking effects at various locations.
  • Different scales exist for measuring magnitude (Richter, Body-Wave, Surface-Wave, Moment Magnitude) and intensity (Modified Mercalli, European Macroseismic Scale, MSK).
  • Understanding both magnitude and intensity is critical for seismic engineering, disaster risk assessment, and formulating building codes.

Key Concepts

-- Magnitude
A logarithmic measure of the energy released by an earthquake, independent of the observer's location.
-- Intensity
The observed effects of an earthquake at a specific location, which can vary based on distance and local conditions.
-- Richter Scale
A scale developed to measure the amplitude of seismic waves in order to gauge the local magnitude of earthquakes.
-- Modified Mercalli Intensity Scale
A qualitative scale that assesses the intensity of shaking and damage caused by an earthquake, ranging from I (not felt) to XII (total destruction).

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