Before you get me wrong, I am not saying you should keep the keys in your phone, but you can also find a steel with an ATM card size shape and write the seed on it then keep that at the back of your phone, in between your phone pouch, I used to keep my ATM card in this location too, I am just giving this option to those living in countries with natural disasters, be prepared.
Don't do this, it is totally unrecommended no matter where you are living and all you get by doing this is a false sense of security. This 'solution' of yours means you are going to carry your seed phrase anywhere you go with your phone, you are closer to losing your phone, your seed phrase and funds in this way faster than you are ever going to be affected by a natural disaster.
I would definitely be much safer if I saved my seed phrase to Google Drive for safekeeping.
~~~~
So to me, even if the unique system is less secure, storing the seed phrase in Google Drive seems much safer.
A very bad advice, don't store your seed phrase online for any reason, anything stored online is prone to hacking and you will lose your funds even before an earthquake happens, that's if it ever affects you.
I have read a lot of bad advises so far in this thread, too many of what a lot of you are recommending will make you lose your seed phrase faster than you'll ever be affected by a natural disaster. Take note that there is no security in obscurity and trying to go overboard to mitigate instances like natural disasters can make you lock yourself out of your funds, without ever being affected by one of those disasters. Just do it the traditional way, write your seed phrase down or engrave it in steel; make multiple backups of it in different locations, and if you are ever affected by a natural disaster, take it as life; if you survive a natural disaster, you may not be so sad that you lost money, but it'll be a sad event if you use unrecommended solutions to mitigate disasters, but lose your funds because of that without ever being affected by one.