Learn English – A word to describe the second one in 2 things

"Explosion" and "Blast" 100% work in this situation.

The explosion sound made from the bomb was extremely loud.

The blast from the bomb was extremely loud.

If these words become too repetitive I suggest using onomatopoeias.

Onomatopoeias are words that express a sound and could be used as an interjection at the beginning of the sentence.

Boom! The bomb went off after the minute was up.

The "boom" at the beginning of the sentence could be replaced by a variety of different onomatopoeias. Such as "boosh", "bam".

For further list of these words see: List of Onomatopoeias

This is a latent problem.

Latent problems lie undetected until they manifest themselves in a failure.

More widely, anything can be described at latent if it is present but undetected. For example a disease could have latent symptoms - you don't know that you have the disease.