[Lowfer] Hifers at EM68

[JD]

Good work, Mark.  That certainly is where one would expect to find NC, and 
the timing looks correct, though I've never seen it that jumpy in frequency 
before.  Earthquakes, Dex?

The "A" signal...I'd be very grateful if you could spot it again and maybe 
determine its frequency to within a few Hz some day.  I've been hunting for 
it, but it appears never to have been strong or consistent enough here to 
run across it by accident, so I reckon I need to target it more precisely.

John