### A_95 Parameter Calculation issue

Posted:

**25 Sep 2020, 16:35**I will appreciate your help on the following issue regarding A_95 parameter calculation.

I am wondering how SesimoSignal calculates A_95 parameter. As I tried to verify it with the following simple step-signal example:

a = 0 for t = [0,1)

a = 1g for t =[1,2)

a = 0 for t = 2

where "[" means including, "(" means excluding, a is acceleration and t is the time.

According to my simple hand calculation, and considering the area under a^2 since pi and 2g are constants in Arias intensity formula:

The area under a^2 is = 1.0.

To achieve 95% of that area, the acceleration threshold required = sqrt(95)*1 = 0.974679434g.

However using Seismsignal for this example, the value reported for A_95 is 0.99750g.

If we calculate the corresponding area = (A_95)^2*t = (0.9975)^2*(1) = 0.99501, which correspond to 99.5% of Arias intensity.

Thank you in advance!

I am wondering how SesimoSignal calculates A_95 parameter. As I tried to verify it with the following simple step-signal example:

a = 0 for t = [0,1)

a = 1g for t =[1,2)

a = 0 for t = 2

where "[" means including, "(" means excluding, a is acceleration and t is the time.

According to my simple hand calculation, and considering the area under a^2 since pi and 2g are constants in Arias intensity formula:

The area under a^2 is = 1.0.

To achieve 95% of that area, the acceleration threshold required = sqrt(95)*1 = 0.974679434g.

However using Seismsignal for this example, the value reported for A_95 is 0.99750g.

If we calculate the corresponding area = (A_95)^2*t = (0.9975)^2*(1) = 0.99501, which correspond to 99.5% of Arias intensity.

Thank you in advance!