Every state is different... best to check the state laws in California.
In Massachusetts, you can fire a gun of any type 150 feet from an improved road, or 500 feet from a dwelling (unless you have permission from the dwelling owner, then as close as you want).
They might be able to charge you in Mass with disturbing the peace if it was too early or too late... same as playing your stereo too loud.
If you are shooitng blanks in a pre-1898 gun in Massachusetts, it gets really vague. It's not a gun, because there is no projectile. A cop might assume it is, and you might get into trouble, or maybe not. ... test case time. It just hasn't come up yet, so there is no clear law about it.
There may be some grounds for religious expression (which is one of the reasons that black powder can be shipped to your house) or "signalling device" (thank the coast guard for prohibiting regulation of signaling devices). It all gets sorta fuzzy with a pre-1898 gun.
So, in Massachusetts anyway, if you are more than 500 feet from a house without permission to be near, and over 150 feet from an "improved road", you are pretty much clear sailing as far as distance. (There are some other Massachusetts regulations dealing with fire department regs that I will avoid discussing).
There are a couple of towns in Massachusetts that have "discharge of firearm" homerules... mostly heavily populated areas near Boston. I have no idea if a cannon with blanks would be affected. I doubt anyone but a jury would know. If there is a ball in it, it probably would be affected, but you wouldn't wanna shoot a cannon with a ball in it it downtown heavily civilized areas anyway.
Once again, every state is different. You gotta check state and local laws. I am sure there is a California gun owners action group. Find their web site and look for links to state laws in California.
If you are any sort of terms with the local PD, I guess a call would prevent them from going out and looking for the source of the explosions should they be called in. Before doing that, I would make sure you were legal per Ca rules first, so you don't provide evidence to convict yourself.