25th Anniversary of Mount Pinatubo Eruption

The 25th year of the cataclysmic eruption of Mount Pinatubo is on June 15. Mount Pinatubo erupted in 1991 after a 500-year period of dormancy. This eruption is the second largest eruption of this century. The eruption caused fast-moving masses hot ash and gases known as pyroclastic flows, a cloud of volcanic ash that spanned hundreds of kilometers across and massive mudflows or lahars that even after the eruption posed grave danger to anyone near its path.

The eruption on June 15th 1991 coincided with the passage of Typhoon Yunya. This was the climactic eruption of the volcano. The typhoon's passage contributed to the massive mudflows around the volcano. The rain and the suspended ash from the wide eruption column which falls out of the sky collapsed almost every roof of the buildings because of the concrete-like consistency of the mixture.

Close to the volcano were two American military bases, Clark Air Base and Subic Naval Base. These two military bases have been evacuated as they were rendered unlivable after the eruption. Clark Air Base was destroyed by the heavy pouring of ash and later on by the lahars the flowed long after the 1991 eruption.

Effects of the eruption was global. The eruption lowered the global temperature by an average of 0.5 degrees Celsius over the next year. The devastation of the eruption did not stopped after that climactic eruption, it went through several years in form of lahar events, flooding and heavy siltation.

For more information of the Pinatubo Eruption on June 15, 1991, you may download this fact sheet from USGS here.