Hi Chris

>     I suggest that you check the gain setting on
> your SEPUK. You have a choice of SWITCHED gains of
> x100, x200 and x500. If your signal is going off
> scale, can you not switch to a lower gain?

It's already at x100.  I've seen it spike off scale once before, which
was the 8.8 Chilean quake last year (13.000 km away), but this is the
first time it's been off scale consistently for 1-2 hours (which makes
sense since this time the quake was 8200 km away).  Such quakes are
the exception, though.  I'm picking up 100+ of the aftershocks in
Japan down to about 5.2, which is a more useful sensitivity (let's
assume that we're done with the ~9 quakes for some years now...).

> The manual
> (which is worth reading for others using or constructing
> Lehmans) is on line at
> www.mutr.co.uk/images/seismometer.pdf

The correct link seems to be:

https://secure-mutr.co.uk/catalog/images/Seismometer.pdf

>     I bought a x10 period extension board for my 4.5 Hz
> geophones from www.sara.pg.it It works very well and it
> effectively gives me 3 off 0.5 Hz geophones! These are
> well matched for all P and S waves.

Interesting.  How does it work?

-- 
Steinar
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