Yeah, so how have they been working out compared to chemical explosives? Not so good? I guess those ancient aliens weren't so smart after all.
Look on a capacitor. There will be a voltage rating on it. If you don't exceed that voltage you can put the sucker into any LC or RC circuit you can imagine and it will not fail.
Remember what volts are? They're what your granite doesn't produce.
The natural energy required to destroy the Tacoma Narrows Bridge (just north of me) by resonance far exceeded the energy that a few explosives would have released to tear it down. It withstood hours of powerful sustained winds before it finally collapsed. A few dozen pounds of plastic explosives would have released enough energy in a fraction of a second to bring it down.