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Review
Table 1
Main criteria used to distinguish tectonic earthquakes from quarry blasts.
Principaux critères utilisés pour distinguer les séismes tectoniques des tirs de carrière.
| # | Criteria | Earthquake | Quarry blast |
|---|---|---|---|
| 1 | Origin time | Anytime | During working hours |
| 2 | Epicentral location | Almost anywhere | Close to known quarry |
| 3 | Magnitude | Any | Rarely exceeds ML 3.0 |
| 4 | Hypocentral depth | Any | Superficial |
| 5 | P-wave polarity | Depending on the station | Positive on every station |
| 6 | P/S amplitude ratio | Low | High |
| 7 | Presence of surface wave | No except for very shallow earthquakes | Very frequent |
| 8 | S-wave frequency content | Broad band | Narrow low frequency band |
| 9 | S spectral ratio[10-14Hz] / [2-6Hz] | > 0.75 | < 0.75 |
| 10 | Repetition | Variable magnitudes | Very similar magnitudes |
| 11 | Satellite images | No change expected | Apparition of a new quarry |
| 12 | Presence of an acoustic wave | None | Sometimes, at close distance (<30 km) |
| 13 | Other | Ex: Double-couple focal mechanism | Ex : Communicated by the quarry company |
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