Incidentally, the only other similar change I see on the Hockley seismometer
today occurred at 12:18 UT. You can verify for yourself that a sudden change
also occurred in the earth's total geomagnetic and Hn field by looking at the
data at:
http://sec.noaa.gov/ftpdir/lists/geomag/20011022_G10mag_1m.txt

• Geomagnetic field for October 22, 2001