Grant,
Since earthquakes are a major concern, maybe( in order to keep your costs minimized) you might consider a custom stand( mass loaded) to match your speaker measurement requirements and place a special plate designed by Silent Running Audio or perhaps Bright Star Audio on top of it to couple to your speakers. Basically a 6" tall stand with a 2" plate to give you your 8" height requirement. Adona also makes custom stands for speakers.
Since earthquakes are a major concern, maybe( in order to keep your costs minimized) you might consider a custom stand( mass loaded) to match your speaker measurement requirements and place a special plate designed by Silent Running Audio or perhaps Bright Star Audio on top of it to couple to your speakers. Basically a 6" tall stand with a 2" plate to give you your 8" height requirement. Adona also makes custom stands for speakers.