The blast, as I saw on FB was a devastation of the kind of Hiroshima. Quite pathetic that so many lives are lost.

On the matter of security of wallet keys, it is better imagined than experienced. There are so many disasters that could cause same devastating loss; flood, fire, earth quakes etc.

I recall my teacher giving an example of a firm that never thought the twin towers of World Trade Center (WTC) will come down the same day, so he rented offices in both buildings. One of the offices in one of the building was used purely as a safe keep for important documents. As it is today, that proved to be a faulty safe. Cloud storage is the best. Use any of the cloud storage. Use a passworded  word document.