Hazard and Disaster Magnitude Units
Additional Information About the Hazard Extent
Some disaster types may have a reported magnitude in the Magnitude and Magnitude Scale columns of the EM-DAT Public Table. EM-DAT disaster magnitude scales vary depending on the disaster type. The table below specifies magnitude property and units for related disaster types.
| Disaster Type | Magnitude property | Magnitude Unit or Scale |
|---|---|---|
| Earthquake | Size of the earthquake derived from its physical properties | Moment Magnitude1 |
| Flood | Flood extent (area) | km² (square kilometers) |
| Drought | Drought extent (area) | km² (square kilometers) |
| Extreme temperature | The recorded extreme temperature (maximum or minimum depending on whether it is a heat or a cold wave) | °C |
| Epidemic | Number of vaccinated people | Vaccinated people2 |
| Wildfire | Wildfire extent (area) | km² (square kilometers) |
| Storm | Recorded wind speed | kph (kilometer per hour) |
| Industrial accident (Chemical spills) | Chemical discharged volume | m³ (cubic meter) |
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See the following USGS Document. ↩︎
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As the magnitude column provides additional hazard-specific information, it is used to report the number of vaccinated people for epidemics. However, it may not be a good indicator of the magnitude of the epidemic, which is also captured by the health impact. ↩︎