Hi All,

Has anyone noticed something odd on the USGS CA-NV map this afternoon? An earthquake of a 3.2 magnitude that occurred on Monday suddenly showed up today in yellow.

3.2 2001/11/26 18:20:20 39.731N 122.851W 16.0 14 km ( 9 mi) NW of Alder Springs, CA

In consulting with Lowell about how this is possible he researched the matter and this is what he discovered:

In regard to the Alder Springs event. There apparently has been considerable controversy about this. When it first came in, it was listed immediately, but it took about 20 minutes before a magnitude of Ml 3.5 was assigned - the northern California catalog shows it as a Ml 5.0 even now. When no magnitude was assigned, I checked the seismograms, and there was a sizable earthquake recorded in that region at the time (at least Ml>3). But still it was not listed. I thought maybe it was from an artificial source, but the timing was too late in the day for an explosion.

NEIS is now listing the event as a real earthquake. Probably it occurred near a quarry and seismologists had to check to make sure it was not a blast. But really, I have no idea why it took
so long to list it. Having looked at the seismograms at the time of the event, however, I am sure something happened which the responsible seismologists have now determined was an earthquake.
The seismograms were a bit strange, however, and it almost looked like an extended source. It could be that it was very difficult to locate because of the strangeness of the seismograms.

Now that we have an explanation for this one, guess what? Another earthquake appeared over at Lone Pine this evening which occurred last Saturday. What an odd day!

3.0 2001/11/24 01:28:49 36.650N 118.234W 11.3 16 km (10 mi) WNW of Lone Pine, CA

Thanks Lowell...wanna figure out what happened with this one?

Petra - with Don riding shotgun