Hi All. I thought some of you might be interested in –0.0 quakes that Roger referred to. As far as I can remember I never made a prediction for a quake of any kind in the area of Yucca Mountain so I have no idea as to the location of the ones Roger was referring to. Take Care…Don in creepy town

Hi Don,

The earthquakes you list are all tiny, as David noted. In the region of
the network where they occur (all are near Little Skull Mountain), our
network is most sensitive, so almost all earthquakes of magnitude -0.3
and larger are recorded. The smallest located quake on 8/5/2002 was
actually Ml -0.59. In most places earthquakes so small would be of
little interest, but these are near Yucca Mountain, a proposed site for
high level nuclear waste, so we endeavor to record everything above
background. In this network a Ml 0 earthquake is usually well recorded.

Negative magnitudes occur because the local magnitude scale has a
logarithmic term in it for the size of the ground motions. After
amplification, if the recording measures 10 mm, one unit is added to the
magnitude (10 raised to the power of 1 = 10) If the recording measures
0.1 mm = 10^(-1), -1 is added. Thus for small enough "wiggles" the
magnitude can be negative. All deflections are measured electronically,
so the "pen" size is not a factor. Our particular readings of -0.00 are
magnitudes slightly less than 0.00 but not negative enough to read
-0.01. You could see slightly positive values too, shown as "0.00".
Keep in mind that despite all this talk of precision, the absolute
accuracy is lower and depends on many other factors.

Regards,

Glenn

--
Glenn Biasi
University of Nevada Reno
Seismological Laboratory, MS-174
Reno, NV 89557
ph: (775) 784-4576 fax: (775) 784-4165