This has been known for years. See this blog post from 2013 for example: https://garethharney.wordpress.com/2013/06/07/the-forgotten-coin-dating-the-destruction

This has been known for years. See this blog post from 2013 for example: https://garethharney.wordpress.com/2013/06/07/the-forgotten-coin-dating-the-destruction-of-pompeii-and-herculaneum/ https://garethharney.wordpress.com/2013/06/07/the-forgotten-... The key piece, among other circumstantial evidence that was already known for decades, is a coin found many years ago and not this graffiti.