I probably should have also existing bubbles being shaken loose as an additional factor in causing movement.
Some background: A magnitude 7.3 (ML) earthquake near Landers, California appears to have triggered seismicity in several locations in the western US - especially in areas with hydrothermal systems or sites with recent volcanic activity occurred such as Long Valley Caldera (Hill et al, 1993, Linde et al., 1994, Johnston et al., 1995). The epicenter of the Landers quake was several hundred kilometers south of the Long Valley Caldera - what these authors suggest is that bubbles within magma or hydrothermal systems were "shaken loose" as a result of the earthquake passing through the fluid and these bubbles created extra pressure that was exerted on the crust, inducing seismic activity.
It's interesting to note that Linde et al (1995) speculated that there may have been volcanic eruptions triggered by other regional earthquakes including 1707 eruption of Mt. Fuji (Hoei M=8.4), Mt. Calbuco in Chile - 1960 (M=8.6), and the 1980 "Pozzuoli crisis" after the (M=6.9) Iripina quake. I found this interesting, especially given the recent set of posts by Jessica Ball (Magma Cum Laude) discussing the possibility of volcanoes triggering earthquakes (Part 1 and Part 2).
Hill et al (1992) Seismicity in the Western United States Triggered by the M=7.3 Landers, California Earthquake of June 28, 1992, Science vol. 260, pp. 1617-1623.
Linde et al (1994) Increased pressure from rising bubbles as a mechanism for remotely triggered seismicity, Nature vol. 371, pp. 408-410.
Johnston et al (1995) Transient Deformation during Triggered Seismicity from the 28 June 1992 Mw=7.3 Landers Earthquake at Long Valley Volcanic Caldera, California, Bulletin of the Seismological Society of America, vol 85, no. 3, pp. 787-795.