If there's a natural disaster cutting off electricity for days, trading bitcoin should be least of your worries really. Priorities man.
sorry I meant to say, how does one trade with BTC
ie. how does one buy food/water with BTC in such circumstances if BTC is the most preferred currency for trade (like Venezuela)
My answer to to that is NO. You can't trade anything in bitcoin if you do not have any electricity for a reason that electricity and internet is a must or really essential in accessing bitcoin or any other cryptocurrenc I think and in doing such activity in here like trading. In case there was no eletricity, you surely cannot connect and trade and I must say paper money and coins that is tangible are the ones you can trade not cryptocurrencies.