Mt. Rainier is ranked as one of the most dangerous volcanoes in the world. And it doesn’t even need to have an explosive event. (I’m not even sure Rainier is possible to have an explosive event.)
It does have a lot of hot water inside, and a very unstable rock. A small earthquake, landslide, etc. could cause a release of that hot water, instantly melting the snow and ice, mixing with the mud and the lahar.
I have done work where new subdivisions are going in west of Mount Rainier. All of the old trees from the last lahar make putting in sewer lines difficult. I wonder how many folks that buy those homes know they are sitting on 30 feet of old mud and trees deposited just 500 years ago (which reached Tacoma and the Puget Sound)?
I had no idea there was a lahar that recently, and that the historical geology was that close to the surface.
I always assumed Mount Rainier was explosive since it's so close to Mount St. Helens, but that's based on no factual knowledge at all.