I'm enjoying this book...

From Pompeii, by Robert Harris:

He reached for the decanter but stopped, his hand poised in midair. The heavy crystal glass was not merely shaking now: it was moving sideways along the polished wooden surface. He frowned at it stupidly. That couldn't be right. Even so, it reached the end of the sideboard and crashed to the floor. He glanced at the tiles. There was a vibration beneath his feet. It gradually built in strength and then a gust of hot air passed through the house, powerful enough to bang the shutters. An instant later, far away - but very distinctly, unlike anything that he, or anyone else, had ever heard - came the sound of a double boom.

and:

...the thermal energy released during the A.D. 79 eruption would have been roughly 2,000,000,000,000,000,000 joules - or about 100,000 times that of the Hiroshima atomic bomb. (that number was in scientific notation, but I have no idea how to type exponents.)