Table A.2 Lower range probabilities
Likelihood
of “rare”
phenomena
Event x
Return time (years)
prob = Frequency
equivalent = 1/return
time
P x to see the
even next year
p x min –p x max
High
Having an income of more than
700k US$ in the US in 2017 (1 in
100)/higher bound of likelihood to
have a 7.0 or even higher
magnitude on the San Andreas
Fault line
100–10
0.01–0.1
(10
−2
–10
−1 )
Moderate
Assault by firearm in the US (237
in 100,000 inhabitants)
1000–100
0.001–0.01
(10
−3
–10
−2 )
Low
Influenza death (1 in 5000 to 1 in
1000) per person/an earth tailings
dam breaches on earth per year
10,000–1000
0.0001–0.001
(10
−4
–10
−3 )
Very low
Fatal accident at work (1 in 43,500
to 1 in 23,000) per worker/class 5+
nuclear accident on earth
100,000–10,000
0.00001–
0.0001
(10
−5
–10
−4 )
Extremely
low
Person stricken by lightning (1 in
161,856)
1,000,000–100,000
0.000001–
0.00001
(10
−6
–10
−5 )
Credibility
threshold
lower
likelihoods
exist
Fatality in railway accident
(travelling in Europe) (0.15 per
Billion km)/meteor landing
precisely on your house; a major
Swiss hydro-dam breaching
N/A
Unless data
abound, lower
values should
not be used
1.E-03
1.E-02
1.E-01
1.E+00
1.E+01
0.1
1
10
100
1000
Frequency
Probability
Fig. A.1 Frequency versus probability. Vertical axis probabilities (limited, by definition, to 1),
horizontal axis corresponding value of 1/frequency. Frequency expressed in events per year
276
Appendix A: Making Sense of Probabilities and Frequencies