USA Earthquake Magnitude vs Intensity Quiz

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USA Earthquake Magnitude vs Intensity Quiz

Magnitude scales vs shaking intensity; damage patterns (10 questions).

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USA Earthquake Magnitude vs Intensity Quiz: Quick Study Notes

Understanding the difference between earthquake magnitude and intensity is crucial for comprehending seismic events. While magnitude quantifies the energy released at the source, intensity describes the observable effects and shaking experienced at various locations. This distinction helps scientists assess earthquake power and engineers design safer structures, especially in earthquake-prone regions of the USA.

Key Concepts

Magnitude (Energy) Measures the total energy released by an earthquake at its source. A single earthquake has one magnitude value.
Intensity (Effects) Describes the degree of ground shaking and its observable effects at a specific location. Intensity varies spatially.
Scales Used Magnitude is typically measured by the Moment Magnitude Scale (Mw). Intensity is measured by the Modified Mercalli Intensity (MMI) scale.
Damage Patterns Higher MMI values correlate with increasing levels of structural damage, ground deformation (liquefaction, landslides), and human impact.

Key Takeaways

  • Magnitude is intrinsic: Represents the earthquake’s total energy, a single value for an event.
  • Intensity is extrinsic: Describes the felt effects and damage, varying widely across a region.
  • Moment Magnitude (Mw) is standard: Quantifies energy more accurately for large quakes than Richter.
  • Modified Mercalli Intensity (MMI) is observational: Uses human accounts and observed damage to assign a qualitative rating.
  • Local factors influence intensity: Geology, soil type, building codes, and distance from epicenter significantly affect MMI.
  • Damage directly relates to intensity: Engineering and urban planning use MMI to predict and mitigate earthquake impact.
  • Not directly proportional: A higher magnitude generally leads to higher potential intensities, but not a uniform increase everywhere.

Frequently Asked Questions

What is the primary difference between earthquake magnitude and intensity?

Magnitude measures the energy released at the earthquake’s source, a single value. Intensity describes the shaking and effects observed at different locations, which can vary widely.

Why do different locations experience different intensities from the same earthquake?

Intensity is influenced by factors like distance from the epicenter, local geology (e.g., soft soils amplify shaking), and the type and quality of building construction.

Which scale is used for magnitude, and which for intensity?

Magnitude is primarily measured by the Moment Magnitude Scale (Mw). Intensity is measured by the Modified Mercalli Intensity (MMI) scale.

Can a small magnitude earthquake cause significant damage?

Yes, if it is very shallow and occurs directly beneath a populated area with vulnerable structures, it can cause high local intensities and damage despite a moderate magnitude.

How does building design relate to earthquake intensity?

Building design significantly impacts how a structure responds to shaking. Buildings constructed according to modern seismic codes are designed to withstand higher intensities with less damage than older, unreinforced structures.

GeoQuizzy.com • USA Earthquake Magnitude vs Intensity Quiz

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