Will preformed concrete piers make a sufficient shed foundation in a seismically active region?
Yes , pier blocks are great for sheds make sure you have enough for your project. I usually dig down 1/2-2/3 the height of the pier block to get below the topsoil this reduces the amount of settling and any issues with frost heave in the winter, luckily our winters are not as cold as the Midwest and back east. So frost heave is not much of a problem with the pier dug in, this also reduces the step up.