Danger levels earthquakes - Natural Hazards Portal - Free Printable

The image you've uploaded is a chart from the European Macroseismic Scale 1998 (EMS-98), which describes earthquake intensity based on human perception, impact, approximate magnitude, and building damage. The scale ranges from I (Not felt) to X+ (Extreme), with increasing levels of severity.

Let’s analyze and explain the key components of this chart:

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🔹 Structure of the Chart

The table has five columns:

1. EMS-98 Intensity: The intensity level (I to X+) used to classify earthquake effects.
2. Felt: Describes how people perceive the shaking.
3. Impact: Details the observable effects on people, objects, and structures.
4. Magnitude (Approximate Value): Gives a rough correlation between EMS intensity and Richter scale magnitude.
5. Building Damage (Masonry): Shows visual representations of damage to masonry buildings at each intensity level.

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🔹 Key Observations & Interpretation

#### 🌍 Intensity vs. Magnitude
- The magnitude column shows approximate values:
- I–III: ~2–3
- IV–V: ~3–4
- VI–VII: ~4–5
- VIII–IX: ~5–6
- X+: ~7

> ⚠️ Note: This is an *approximation*. A single earthquake can have different intensities in different locations depending on distance from the epicenter, depth, soil conditions, etc.

#### 🧱 Building Damage Progression
The rightmost column uses illustrations to show how masonry buildings are affected:
- I–III: No visible damage.
- IV–V: Minor issues like rattling windows or small object movement.
- VI: Hairline cracks, falling plaster.
- VII: Cracks in walls, chimney collapse, wall failures.
- VIII: Large cracks, partial structural failure, possible collapse of weak buildings.
- IX: Collapse of many weak constructions; serious structural damage even in well-built buildings.
- X+: Widespread destruction — even earthquake-resistant buildings collapse.

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🔹 Understanding the Scale

This is a qualitative macroseismic scale, meaning it measures the effects of an earthquake rather than its energy release (like the Richter or Moment Magnitude scales).

#### Example: What does VII (Very Strong) mean?
- Felt: Most people frightened, run outdoors.
- Impact: Furniture shifts, objects fall from shelves.
- Damage: Small cracks in walls, falling plaster, chimneys damaged.
- Magnitude: ~5
- Building Damage: Moderate damage to ordinary buildings; large cracks in older ones.

#### Example: IX (Violent)
- People panic.
- Many weak buildings collapse.
- Even well-built buildings suffer heavy damage (e.g., wall failure, partial collapse).
- Approximate magnitude: ~6

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🔹 Why Is This Useful?

The EMS-98 helps:
- Assess earthquake impacts after an event.
- Guide emergency response and damage evaluation.
- Compare historical earthquakes.
- Inform building codes and urban planning.

It's especially useful for regions where instrumental data may be limited, relying instead on eyewitness reports and observed damage.

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✔ Summary

| Intensity | Felt Level | Approx. Magnitude | Building Damage |
|----------|------------------|-------------------|-----------------|
| I–III | Not felt / Weak | 2–3 | None |
| IV–V | Light / Moderate | 3–4 | Slight |
| VI–VII | Strong / Very Strong | 4–5 | Moderate |
| VIII | Severe | ~6 | Heavy |
| IX | Violent | ~6 | Very heavy |
| X+ | Extreme | ~7 | Total collapse |

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💡 Final Note:

This chart illustrates that intensity (how strongly an earthquake is felt) varies by location, while magnitude (the total energy released) is fixed for a given quake. So one earthquake might have a magnitude of 6.0 but cause intensity VII in some areas and only V in others.

If you have a specific question about interpreting this chart (e.g., "What would happen in a magnitude 5.5 earthquake?" or "How do I estimate intensity from damage?"), feel free to ask!