[Shake-dev] Can we still use Intensity Scale based on Wald99??

[Bruce Worden]

Hi,

The ground motion to intensity conversion equation (GMICE) can be  
selected by the operator. Wald99 is one option, though you may find  
AK07 (Atkinson & Kaka, 2007) works better for your environment. The  
other module that's currently available is FM2010. The complete  
references for all of these modules are near the top of their source  
files. There is the also the option to implement your own GMICE --  
simply base the interface on one of the existing modules.

You make a good point about the PGA and PGV values, since these may be  
just one source of data in the intensity map, and the relationship  
between the PGA and PGV in the scale and intensity has always been a  
bit loose. For Wald99 we actually use a ramp function from MMI 5 to  
MMI 7 that transitions from MMI derived from PGA to MMI derived from  
PGV. But the correlation between intensity level and felt effects and  
damage remains valid, and I think the PGA and PGV values are still  
valuable as guides to instrumental intensity. However, if operators  
would like the option to remove the PGA and PGV from the scale, we  
would take it under advisement.

Bruce


On Dec 9, 2010, at 7:03 PM, WSC wrote:

> Hi,
>
> I have two questions about the Intensity Scale:
> 1、Is the Intensity Scale derived from Wald99(a and b)?
>      As we know,there are about four I=f(pga,pgv)equations from  
> Wald99(a,b), i think the intensity is consitent with these four  
> equations, isn`t it?
> 2、if so,can we still use the Intensity scale to represent the  
> intensity map??
> I think the intensity in SM3.5 now is obtained by weighted the  
> ovbservation data,the converted data based on wald99(P->M) and  
> estimated data(IPE),now the intensity data includes not only the P- 
> >M data,but observations and IPE derived intensity data,so now we  
> still use this Intensity scale to reprensent the intensity map,is it  
> reasonble?
>
> Thanks,
> WSC
>
>
>
>
>
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