You possibly have two different scenarios here.
Your question seems to be about keeping them charged and ready for an earthquake. A simple, literal answer to that problem would be to link them all in parallel and keep them at float voltage. The simplest PWM controller or even an adjustable buck module set to about 13.8V could do that. Panel size would be very modest; just enough to compensate for self discharge.
However….
Things get a whole lot more complicated if you plan to draw down on them and recharge. If you figure on staying in place for days or weeks after your emergency, then panel sizes and controller types have to be calculated based on you expected daily power consumption. Lots of good replies in this thread already.
One thing to note about the Victron controllers is that they need the panel voltage to be at least 5V over battery voltage to start charging. After that, +1V is sufficient. You may have trouble getting any charge at all on a heavily overcast day. I don’t know if other brands are comparable.
If you are serious about building a real emergency rig, take Chris’s advice and get good quality gear from the outset.