Hi Geoffrey,

This is happening because your system is saturation. Looking at your event file it 
looks like you are using a 8 Bit A/D converter. Upgrading to a 12 or higher bit 
converter would give you a lot more dynamic range so this would happen less often.

Regards,
Larry Cochrane
Redwood City, PSN

Geoffrey wrote:
> Hey guys;
> 
> In Winquake
> 
> event file: 091025.105300 from GVA
> When I integrate this event the ground seems
> to drop at somewhere in the S or L wave and does
> not return to normal ?
> 
> Does anyone understand this integrated waveform ?
> 
> It looks to me like only the DC blocker circuit
> is returning the signal to its baseline.
> 
> I have seen this before but do not understand it.
> 
> In my wildest imagination I can in no other way
> explain this results of the integration.
> 
> Is Arizona slowly sinking into the Earth ?
> Will we have another ocean where there used to be desert ?
> 
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