Can someone help me understand why the markets sometimes explode with rapid high volatility at 8:30am EST USA on days when there is no 8:30am news?

I see now after further research - sometimes there is minor news that wasn't showing up on my calendar.

Now the question - how do I delete this post? The replies on NexusFi appear incorrect as there is no delete option offered when I edit.

I know you probably don't want to hear responses now but I think 8:30 is just a psychologically important time at 1 hour before open. There is also likely muscle memory to put a trade on with the algos on days with no news at this time.