FORCES OF NATURE - Fixation, fascination, consternation

Today Mr. E has continued his 'what ifs' but instead of dinosaurs it is back to his good old Forces of Nature what ifs.
Back when he started kindergarten, he was completely undone by the fire alarm drill at his school. The alarm is was so loud that it even hurt my ears, but that was the year we started to learn about Mr. E's auditory sensitivities.
After that first incident, Mr. E started to ask questions about fires. When he finds a new fixation we have a hard time getting him to focus on anything else. It literally is an everyday fixation, a lot of 'what if' questions and he seems to see anything and everything that looks like or reminds him of the fixation.
Well over time fires turned into volcanoes then meteors then black holes then earthquakes then tornadoes and hurricanes then tsunamis ect. ect. ect. It would take about 45 min every night at bedtime to settle his mind down.
This is a small sample of how it would go down:

" mom, is there going to be a fire tonight"

We used to tell him that if there was a fire, we know what to do, but we quickly realized that the best thing was to say 'no there will not be a fire'

"Mom is there going to be an earthquake tonight?"
"No bud"
"Mom if there is an earthquake and we sleep through it are we all going to die?"
"Bud, there isn't going to be an earthquake tonight."
"Mom if there is an earthquake will grandma and grandpa feel it too?"
"Bud yes we all would feel it but there isn't going to be an earthquake."
"Mom would the earthquake scare Sally(our dog at the time)? Would she die or bark and wake us all up?"
"Bud, I promise there is to going to be an earthquake, we are safe"

"Mom is a meteor going to come down and hit our air conditioner and explode it?"

Preface: we had just moved into our new house and told curious Mr. E not to touch the utilities downstairs or the air conditioning unit outside. We didn't want him pushing buttons or taking things apart, we arned him that it could be dangerous if he touched it.

"No bud, no meteors are coming down"

" mom what if a boulder came down the mountain and crashed into our house"

Preface again: we made the big mistake of driving the kids up to see a house setting on the base of the mountain that had a boulder roll down and crash through it. The family had already moved out and you could still see the boulder.

" no a bolder could never reach our house, we are to far from the mountain and it would hit a whole bunch of houses before it ever hit ours."
"Mom what if it came down the mountain and jumped over all the houses and hit ours?"

(Well since we have a target on our house and boulders are alive..) so that is just a small sample of the conversation we would have every night before bed.

Tonight he started asking a lot of earthquake 'what ifs' and I wasn't doing so well at answering them all, plus I was tired and his mind was active, so I brought out one of his birthday presents I got him about 2 months ago and was saving for the actual day. I handed it to him and said "Happy early Birthday". He smiled and was excited to receive the forces of nature book. I told him that if he has questions then read the book. It seemed to really help and we sent him to bed with it.