Hi All. There is more evidence that geomagnetic storms have a direct influence on some of the quakes. However the main problem still remains. That is finding the area in which sufficient amount of strain has built up to cause a 6.0Ms+ quake.

Following earlier analyses this month regarding the comparison of geomagnetic index A (or Ap) this month with earthquake counts in California, Table 1 (not my figures) shows counts for the past week on the USGS California web listing. The highest numbers in all magnitude categories fall on October 28. October 27 is a local minimum in all categories. Early in the week earthquake number and A-index are generally low, increasing with the moderate geomagnetic storms mid-week.
Although numbers of earthquakes in all categories is highest on October 28, the factor increase over the first 6 days of the week of events on October 28 is greatest as the lower magnitude limit is increased. This suggests that geomagnetic triggering tends to trigger larger events at a greater rate than smaller events.

This is important for hazard analysis since it is precisely these larger events which may present a hazard. Furthermore, the number of total recorded events remains within a factor of about 1.5, suggesting that the triggering is taking events, which would occur anyway, and increasing their magnitude. It is important to understand these factors in any seismic alert, which may be produced on the basis of geomagnetic storminess.

Table 1: Final California Earthquake counts for the week:

Date: Ml>0.0 ML>=1.5 ML>=2.0 ML>=2.5 A-Index (Middle latitudes)

October 22 28 16 8 5 7
October 23 22 18 5 1 13
October 24 36 28 9 2 10
October 25 39 30 16 6 9
October 26 35 27 13 1 9
October 27 31 22 5 2 3
October 28 47 35 22 10 17

Rate/hour 1.32 0.98 0.39 0.11 8.5 (Average)
(Oct 22-27)
Rate/hour 1.96 1.45 0.92 0.42 17
(October 28)

Factor 1.48X 1.48X 2.35X 3.81X 2.0X
increase over background
of Seismicity on Oct 28.

There were 3 Ms 6+ quakes on the 29. A Ms 6+ earthquake hit in the Kuril Islands south of Kamchatka. The other two were New Britain where an Ms 6.3 occurred in the morning and the So.Sandwich Islands where an Ms 6.1 also occurred on the same morning. These are the only earthquakes in the Magnitude 6 range to occur that day. Since there were no earthquakes of Ms>=6 from 6 October through 25 October, having 3 within 14 hours represents a significant increase in activity at these magnitude levels. However this may be nothing more than a coincident and does need continued watching for repeat patterns at other locations. Take Care…Don in creepy town.