Typhoon Yunya, known in the Philippines as Typhoon Diding, was a strong tropical cyclone whose landfall in the Philippines coincided with the 1991 eruption of Mount Pinatubo. A small tropical cyclone, Yunya rapidly developed from a tropical disturbance near East Samar on June 11. By June 13 the storm had reached typhoon status as it moved west-northwest near the Philippines. Yunya attained its peak intensity the following day with estimated winds of 145 km/h (90 mph); however, strong wind shear soon impacted the typhoon and caused it to rapidly decay. The storm struck southern Luzon early on June 15 as a minimal typhoon before moving over the South China Sea later that day. After turning north and weakening to a tropical depression, the system brushed the southern tip of Taiwan on June 16 before dissipating the following day.
Yunya as a Category 2 typhoon on June 13
Satellite image of Yunya as it made landfall; the eruption column from Mount Pinatubo (in dark grey) can clearly be seen through the storm's clouds
The colossal eruption of Mount Pinatubo on June 15, partially obscured by rainclouds from Yunya
1991 eruption of Mount Pinatubo
The 1991 eruption of Mount Pinatubo in the Philippines' Luzon Volcanic Arc was the second-largest volcanic eruption of the 20th century, behind only the 1912 eruption of Novarupta in Alaska. Eruptive activity began on April 2 as a series of phreatic explosions from a fissure that opened on the north side of Mount Pinatubo. Seismographs were set up and began monitoring the volcano for earthquakes. In late May, the number of seismic events under the volcano fluctuated from day-to-day. Beginning June 6, a swarm of progressively shallower earthquakes accompanied by inflationary tilt on the upper east flank of the mountain, culminated in the extrusion of a small lava dome.
Eruption column on June 12, 1991
Pinatubo as viewed from the north in late April 1991. Grayish-tan ash and several craters from the April 2 phreatic explosions are visible at the left.
View to the west from Clark Air Base of the major eruption of Pinatubo on June 15, 1991. The June 15–16 climactic phase lasted more than fifteen hours, sent tephra about 35 km (22 mi) 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 eruption cloud a few minutes after the start of the climactic eruption