The blast, as I saw on FB was a devastation of the kind of Hiroshima.
As an aside, I can't believe there were only around 100 casualties in that blast. It looked like it would have killed a lot more people than that, though I don't know how dense the population was in that particular area at the time. Scary stuff.
To answer both, at Hiroshima the count is between 50 000 and 100 000 from the initial blast, the explosion in Lebanon pales in comparison, but although powerful enough it was "detonated" at ground level so starting from the blast area the force start to lose power far faster because of multiple buildings, in Hiroshima the blast was in the air at 500(!?) meters the wave was direct to almost everything in its range.
In this case, as far as I can see from Google maps although the area is heavily populated along with the port still the buildings are around 200-300 meters from it, enough for the blast to become less deadly, although the damage looks like a ww2 bombardment the severity seen on buildings doesn't always translate in human deaths, fortunately. The same happened in Oklahoma where only 4 out of ~160 were from outside the targeted building.
Furthermore, share the backups and ways to retrieve coins from backups to at least one person who you love and trust the most is key. Accidents (maybe death) can happen to everyone so don't keep all things for yourself alone, then if something bad happens, your coins will be lost forever.
I have a feeling that the chances of the person you "trust' to steal those keys from you are growing proportionally with the value of your coins, and I've heard of enough family dramas to think that there are higher chances for a friend to rob you than for all your house to go up in flames.
Having multiple back-ups is clearly a solution but I wouldn't really deal with riddles when "encrypting" it, one baseball ball in the head and none of your riddles won't make sense anymore.