My apologies, John. I was using the word "loading" in the sense that Chris used it in his post of April 18 - "Would have to have some measure of region-wide _water load_". In other words, I intended it to mean "added load due to the weight of rainfall [specifically - the subject of this portion of the overall thread]." I should've made that more clear.

So, my question, is still whether or not rainfall load could possibly make a meaningful difference to the stress at depth. And, yes, of course I understand that the total stress comprises several factors - tectonic stress, gravity/tides, and the extra stress in the form of additional clamping force you refer to elsewhere resulting from the attempted expansion of rock due to additional vertical force. But this portion of the thread was provoked by Chris' suggestion that somebody else had suggested large rainfall amounts as a triggering mechanism for quakes.

Chris has suggested I, or someone else, get the data and look for a correlation, and also provided some relevant calculations. I'll respond to that post there.

Mike Williams