Given recent discussions on this board regarding the effect of CME, geomagnetic
effects and flares on seismicity, I thought someone might notice this. But since
no one else has posted this observation yet, I think I will get the first crack after all.

The Anza earthquake occurred at 11:56 p.m. PST, which is nearly exactly
midnight there by sun-time. As pointed out many times recently when a flare
occurs the areas most affected are at sub-solar and anti-solar latitudes - that
is where it is local sun-noon and local sun-midnight. So was there a flare that
may have triggered the Anza earthquake. Indeed there was and it was reaching
it's maximum just as the Anza earthquake occurred. The flare had started
about 20 minutes earlier and reached maximum output at 12:09 a.m. PST.

The flare had the following parameters:

Flare # START MAX END CLASS

9180 + 0734 0809 0819 M3.2

Flare #9180 was the second largest in more than a week, the last large flares
occurred on October 28 - M3.6 and Oct 22 (M6.5). About an hour after flare 9180
several significant earthquakes occurred including the Ms 7.0 in
New Britain and the Anza earthquake in southern California. The
Anza event occurred at 07:54 UT near the maxima of flare #9180
and occurred while the epicenter was exactly anti-solar. It is
likely that this flare was responsible at least in part for the
timing of this rupture.

For general space weather conditions see:
http://sec.noaa.gov/today.html
For Solar flare data see:
http://sec.noaa.gov/ftpdir/indices/events/20011031events.txt

• Solar flare data