It can't affect the value of bitcoin. Even if there will be any natural phenomena to occur (Hoping it won't happen) because bitcoin's price still relies on how the people frequently use it. If there will be a big war to happen, it will still rely on the usage like merchants who accept bitcoin, miners or people who cashes-out to pay bills or for personal needs and etc. There are a lot of factors that affect the price of bitcoin in the market but I just don't think that the disasters you stated will have any affect on it.