The first waves from quakes, P waves, are sound waves. Lowell Whiteside used to post here and he sent me his Comps paper for his Ph.D. in 1990, which was about distant triggering of quakes. He never published this, and then the triggering was so obvious from the 1992 Landers quake that papers were published by others on that. What is new in you link is the information on how triggered quakes are delayed: that is very interesting.
See my post above on the Queen Charlotte quakes maybe triggering Nevada quakes.
On that site there is also a link to an article that the San Andreas at Loma Prieta is stronger than they thought. I guess I better send that out to HW and a couple of her students.
Chris