A few years back I believe it was three ski patrol officers were killed on Mammoth Mountain. One fell through the snow into a void that had formed filled with CO2 and the other two were killed trying to rescue him.
Very few people realize that the entire valley containing Mammoth Lakes and extending all the way across 395 to Crowley Lake is one giant caldera, and Mammoth Mountain is just one lava and cinder dome. When you drive down the Owens Valley, you pass through vast lava fields and a number of cinder domes,
Mammoth Mountain is one hell of a big cinder dome!
You can see it clearly from the hills around Clayton almost any normal day.