Blunder Question on annual probability of exceedance

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Sujan Raj Adhikari

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Dec 8, 2020, 10:55:31 PM12/8/20
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Hello Openquake user group

if I want to calculate the annual probability of exceedance of 2% in 50 years,5% in 50years, 10%in 50 years, 20%in 50 years 40%in 50 years and 50%in 50 years
how can I define it in Hazard output? is following the correct way or? please give me your thoughts.

[Hazard output]
export_dir = /tmp
individual_curves=true
mean_hazard_curves = true
quantile_hazard_curves = 0.15, 0.50, 0.85
hazard_maps = true
uniform_hazard_spectra = true
poes = 0.02, 0.001, 0.005, 0.0021, 0.001, 0.000404

regards
Sujan

Graeme Weatherill

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Dec 9, 2020, 2:28:38 AM12/9/20
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Dear Sujan,

Your numbers are partially right. The probabilities of exceedance given in the poes correspond to the investigation time that you set, which should be 1 in the case you show.

You could either set the investigation time to 50 years and then define the poes as 0.02, 0.05, 0.1, 0.2, 0.4 and 0.5 respectively, or set the investigation time to 1 year and set the poes to 0.000404, 0.001025, 0.002105, 0.004453, 0.0101645 and 0.013767 respectively. Remember the relationship between rates (lambda), probabilities of exceedance (P) and investigation time (T) are expressed through the Poisson formula: P(T) = 1 - exp(-lambda . T).

If you are using the one year investigation time and corresponding poes then try to avoid rounding too much, especially at the higher probabilities.

I hope that helps.

Regards,

Graeme
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Sujan Raj Adhikari

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Dec 9, 2020, 6:43:38 AM12/9/20
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Thankyou Graeme, thankyou verymuch for this answere.
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