Okay, Don. I have now read both articles that you referenced in this thread -- your posts #31291 and #31292. So I now have a better understanding of the calculation needed to arrive at a valuation of stress change. The article you suggested above (Static Stress Impact...) provides the details of the mathematical computation, while the other article (Stress Triggering of the 1994 M=6.7...) provides a somewhat fuzzy idea of the Coulomb criterion (and how stress change is calculated) in the third paragraph.

But it was that latter article and its contents that I found most troubling.

My elder son is an "urban real estate developer" in Los Angeles -- in other words, he has 2 high-rise condo projects under construction in downtown L.A.

Reading this article about how stress has been transferred to the central L.A. basin increasing its stress by >1-bar is somewhat discomfiting. Has that now put the Elysian Park Fault or the Santa Monica Fault or the Newport-Inglewood Fault close to its failure threshold? Is this increase in stress enough to put it over the edge? Did this >1-bar increase in stress from the Northridge and San Fernando quakes advance the eventual occurrence of a quake in that region by a decade...or more?

Of course, the authors put in a disclaimer at the end stating that they do not know "how close the major faults are to failure," so the "results cannot be used to predict the timing of large earthquakes."

Then the other article states that there is an implication "that a very small change in Coulomb stress (approximately 0.5 - 1.5 bars) can influence the slip distribution of a large earthquake."

Scary stuff! Ah, just one more thing for a mother to lie awake and worry about during the middle of the night.