During and after Katrina we found out that cash is king. With communications down for a few weeks you could not use credit cards. Only cash or a local check (usually if they knew you). We learned that lesson from hurricane Andrew and always kept cash in the safe.
I remember being in Lowe's right after Katrina with a flashlight trying to find the correct plug to connect to my neighbors generator.
In light of the bank runs in Cyprus, these people have not had access to their money for 12 days!
My suggestion is to have a plan, carry cash, and be aware of what is happening in the area that you are in.