Products of the 1907 eruption of Shtyubel' volcano, Ksudach Caldera, Kamchatka, Russia

On March 28, 1907, a sequence of explosive eruptions within the Ksudach Caldera Complex partially destroyed Shtyubel' Volcano, leaving a tuff cone with a 1.5 km in diameter horseshoe-shaped crater filled with a deep lake. The eruption can be subdivided into four phases. The first phase opened the vent and dispersed about 0.02 km ³ of pyroclastic fallout within Ksudach Caldera. The second phase produced a Plinian column that distributed about 1.5 km ³ juvenile pyroclastic fallout to north-northeast and southeast. The third phase was characterized by a powerful blast explosion toward the north-northeast in a 60° sector. The fourth phase consisted of a series of shallow hydromagmatic eruptions that emplaced five pyroclastic surge deposits with ash cloud surge beds at their tops to the west-northwest. Analyses of deposit structures, particle textures, and fragment components indicate that the first two phases were magmatically driven. However, the last two phases were increasingly hydromagmatic. -from Authors