The darker, circular area near the volcano shows darker particulate matter associated with the 0553 and 0611 eruptions in table 2. The more diffuse plume over the South China Sea west of Luzon is ash from earlier eruptions. Satellite imagery suggests that the cataclysmic stage of eruptions began about 1027 on June 15 and lasted for over 21 hours. Figure 4 . Rate of expansion of the Mount Pinatubo ash plume following the paroxysmal eruption of June 15-16, 1991.
Gray areas are landmasses.
An extensive ash shield achieved heights of 25 to 30 km. The ash from this phase accounted for over 95 percent of the plume's 2,700,000-km 2 areal coverage. Figure 5 . The extensive canopy of ash over Luzon and the South China Sea was produced after nearly 5 h of continuous eruption during the paroxysmal event. The total ash plume continued to grow for a total of 18 h.