Why We Still Need to Monitor the Ridgecrest Earthquakes

  A error in one of the averages cropped up as a result of adding data to existing tables. The result is that correlation for the activity and the daily tallies of earthquakes agrees slightly better with the observed values.

The formulas for the correlation of activity with time suggest some sort of relaxation phenomenon taking place.

The stress index had to be eliminated as a good indicator of daily earthquake activity but it still might play a role in indicating peak earthquake magnitudes. There is a lot of variation in the daily peak magnitudes so it is difficult to rule out the possibility. This morning's M4.13 earthquake in the Ridgecrest area points out that the peak magnitudes need to be watched.

The M7.1 earthquake appears to be somewhat exceptional for the area since its deviation from the SI peak magnitude is greater than two standard deviations.

Edit (Jul 23): Miscalculated the 2σ error bounds. Used the std dev of pmag_obs when I should have used that for the difference of the two pmags. Replaced the pmag plot with a corrected version. The M7.1 earthquake appears to be rather unusual.

Supplemental (Jul 24): An alternative hypothesis is the peak magnitudes are part of the population of aftershocks and are declining exponentially. If so, one would conclude that yesterday's M4.13 earthquake was within expectations.