Until 1991, Pinatubo was an unremarkable jungle ridge with no eruption in
living memory, home to the Aeta people. On 15 June 1991 it produced the
second-largest eruption of the 20th century (VEI 6): a column 34 km high, pyroclastic
flows down every major drainage, and - as Typhoon Yunya passed overhead - a rain of
water-laden ash that collapsed roofs across Central Luzon. About 850 people died; the
summit lost 259 m, collapsing from 1,745 m into the 2.5-km caldera you see
here. Nearly 20 million tonnes of sulfur dioxide cooled global temperatures by about
0.5 °C for two years. PHIVOLCS and USGS forecasts prompted evacuations credited with
saving thousands of lives.
Monsoon rains then filled the caldera to form Lake Pinatubo - a jade
crater lake about 900 m above sea level, 1.8 km² in area and 95–115 m deep. In 2001
workers cut a 5-m notch in the low Maraunot rim to lower the lake; in July
2002 that wall failed anyway, releasing ~160 million m³ of water toward Botolan.
Trekkers reach the rim today from Santa Juliana, Capas, across the O'Donnell lahar
fields. The Before 1991 button rebuilds the lost mountain. NASA's SRTM was
flown in 2000, nine years after the eruption, so no radar ever measured the
old summit - but the lower and mid flanks that survived are still the original
edifice. This view samples those real SRTM slopes on a ring around the volcano and
projects them up to the documented 1,745 m summit that stood ~1 km south of
today's lake, filling in only the ~260 m of cone the eruption removed. The surface is
draped in real pre-eruption imagery: a Landsat 5 true-colour scene from
25 March 1990, fifteen months before the climax - the old forests, gullies
and summit clearings as the satellite actually saw them. Base and flanks are measured
data; only the missing top is interpolated to the cited height. Lake bathymetry is
modeled from distance-to-shore.