I remember it in a 1959 National Geographic article - an entire mountainside avalanched down into a ravine, which created a lake, and Old Faithful’s timing was altered. Pictures of kitchens with cupboard contents scattered about. We had just returned from Japan & remembered earthquakes that made everything in the house move about.
The scarp on the east side of the road from the reservoir was about ten feet high. The east side of the dam was visibly lower. Below “quake lake” to the north, some campers were killed in their tent when overrun by a giant boulder. Many campers died when the side of the hill slid into quake lake. The corps of engineers had to figure out how to stabilize, then drain quake lake before it had a cataclysmic failure, which they accomplished.