View to the west from Clark Air Base of the major eruption of Pinatubo on June 15, 1991. The June 15-16 climatic phase lasted more than fifteen hours, sent tephra 30-40 km into the atmosphere, generated voluminous pyroclastic flows, and left a caldera in the former summit region. Later dubbed Black Saturday, the day of darkness stretched for 36 hours. The day included a black blizzard of coarse sand, more than 50 earthquakes, volcanic thunder, brilliant lightning, and orange fireballs.