Steam Blast Eruptive Column Steam-blast eruption from the summit of Lassen Peak during an early phase of its 1914-1917 eruptive activity. This is one of a series of photos showing successive stages in the development of a small pyroclastic column that ejected no juvenile magma but only finely broken rock fragments as it excavated a crater in the 27,000-year-old Lassen Peak volcanic dome. Photo by B. F. Loomis, June 14, 1914.