Many eruptions are explosive[1], like Mount St. Helens in 1980. Here's a small explosive eruption where you can see the shockwave and eventually hear it when it hits the ship the cameraperson is on: https://www.youtube.com/watch?v=BUREX8aFbMs
I remember seeing on a TV program about an eruption where some people were monitoring a volcano from some miles away at an airport where they thought it was probably safe.
And the comment was made that if the pyroclastic flow reached them, the first they would know about it, at night, was when the runway lights vanished.
And the comment was made that if the pyroclastic flow reached them, the first they would know about it, at night, was when the runway lights vanished.
Very different from magma gently flowing out.