Environmental Assessment
Volume E-3.6
Tailings Facility
Natural Risks
Ambatovy Project
43
January 2006
Table 3.6-1 Description of Risk Criteria for Mining
Ranking
Categories
Likelihood of Occurrence (Probability)
Magnitude of Consequences
Overall
Risk
extremely low
1
negligible chance of occurrence, <1:10,000 yr
“doubt it will ever happen”
1
no fatalities possible,
minor to no damage beyond owners property
1-4
low
2
not likely to occur, 1:1,000 to 1:10,000 yr “highly
unlikely to happen”
2
no fatalities anticipated,
minor damages beyond owners property
5-8
moderate
3
moderate frequency of occurrence 1:100 to 1:1,00 yr
“it could happen”
3
no fatalities anticipated,
moderate property damages
9-14
high
4
frequent occurrences, 1:10 to 1:100 yr
“it has happened, or it probably will happen”
4
some fatalities possible,
large property damages
15-19
extremely high
5
very frequent occurrences, >1:10 yr
“happens all the time”
5
large number of fatalities possible,
extreme property damages
20-25
Note:
1. Ranking Category “Extremely Low” signifies negligible occurrence potential.
2. Details above adapted from Pelletier and Dushnisky (1993) and Davies (1998)
