Mount Pinatubo, Philippines 1991

 

Mount Pinotuba, Philippines (1991)

Introduction:

On June 15, 1991, the second-largest volcanic eruption of the 20th century occurred at Mount Pinatubo in the Philippines and the eruption's impacts were present for many following years (USGS, 2005).

Mount Pinatubo ash cloud on June 12, 1991; three days before eruption (USGS, 2005)

Destruction:

In total, the eruption cost $700 million in damage, "$100 million of which was damage to 16 aircraft flying at the time of the eruption and $250 million in property with the rest a combination of agriculture, forestry, and land," (USGS, 2022). The eruption produced high-speed avalanches of hot ash and gas, giant mudflows, and a cloud of volcanic ash hundreds of miles across and lasted for 14 minutes (USGS, 2005).  The eruption ejected massive amounts of tephra and produced pyroclastic flows, forming a small summit caldera whose floor is now covered by a lake (Global Volcanism Program, 2013). The huge pyroclastic flows roared down the flanks of Mount Pinatubo, filling once-deep valleys with fresh volcanic deposits as much as 660 feet thick (USGS, 2005). 

Lahar coverage in early August 1992. By 1995, more than 400 km2 of land was buried by lahars (NASA, 2001)

The ash cloud rose 22 miles into the air and at lower altitudes, the ash was blown in all directions by the intense cyclonic winds of a coincidentally occurring typhoon, and winds at higher altitudes blew the ash southwestward (USGS, 2005). A blanket of volcanic ash and larger pumice pebbles covered the countryside and fine ash fell as far away as the Indian Ocean (USGS, 2005). Satellites tracked the ash cloud several times around the globe. Typhoon Yumma contributed to poor conditions and gave rise to wet ash, increasing loading on structures with a large proportion of the 847 death toll due to roof collapse (USGS, 2022).

The Subic Bay Naval Station is caked in ash; later abandoned (NASA, 2021) 

Discussion: 

Thankfully, successful monitoring efforts greatly reduced the number of fatalities and saved an estimated 5,000-20,000 lives through mandatory evacuation orders as well as preventing $250 million in property damage (USGS, 2005). The USGS states, "timely forecasts of this eruption by scientists from the Philippine Institute of Volcanology and Seismology and the U.S. Geological Survey enabled people living near the volcano to evacuate to safer distances," (2005). 

Civil engineering efforts include constructing levees, dams, and sediment retention structures since the eruption (NASA, 2001). Today, astronauts and cosmonauts use their long-term observations of Mt. Pinatubo's land change as an example of the types and magnitudes of changes that can be monitored over other volcanic regions (NASA, 2001). 

Video covering the main information surrounding the Mount Pinatoba eruption as well as the worldwide climactic changes it created (History and Headline, 2021)

Typhoon Yumma created disastrous conditions that exacerbated the damage from the eruption. Many of the ~860 deaths were due to structural issues, primarily roof collapse. Existing water damage from typhoon Yumma weakened structures through water damage and made it much harder for the population to cope. The mix of moisture from the typhoon and ash from the eruption created thicker fallout than if there had not been a typhoon. Many ports and naval bases were destroyed and eventually abandoned which continued to destroy the Philipino economy. Had there been retrofitting efforts with pre-existing structures, the water damage and the death toll may have been mitigated more successfully. Space monitoring stations continue to monitor and study Mount Pinotoba's changing land formation. This data is also used in other volcanic locations to work towards better, future volcanic prediction methods.

Sources

Allen, T. (2021, June 15). A CONVERSATION WITH NASA DISASTERS PROGRAM ASSOCIATE MANAGER, JOHN MURRAY. Remembering Mt. Pinatubo . Retrieved October 24, 2022, from https://appliedsciences.nasa.gov/our-impact/story/remembering-mt-pinatubo

Global Volcanism Program, 2013. Pinatubo (273083) in Volcanoes of the World, v. 4.11.2 (02 Sep 2022). Venzke, E                     (ed.). Smithsonian Institution. Downloaded 24 Oct 2022 (https://volcano.si.edu/volcano.cfm?vn=273083).                     https://doi.org/10.5479/si.GVP.VOTW4-2013

NASA Earth Observatory Center. (2001, June 14). Astronauts photograph Mount Pinatubo. NASA. Retrieved October 24, 2022,                from https://earthobservatory.nasa.gov/features/AstronautPinatubo/astronaut_pinatubo2.php

Newhall, C., Hendley II, J. W., & Stauffer, P. H. (2005, February 28). The cataclysmic 1991 eruption of Mount Pinatubo, Philippines, fact sheet 113-97. . U.S. Geological Survey Fact Sheet 113-97. Retrieved October 24, 2022, from https://pubs.usgs.gov/fs/1997/fs113-97/ 

USGS. (2022, March 8). Pinatubo 1991. Volcanic ash impacts & mitigation. Retrieved October 24, 2022, from https://volcanoes.usgs.gov/volcanic_ash/pinatubo_1991.html#:~:text=The%20eruption%20cost%20%24700%20million,of%20agriculture%2C%20forestry%20and%20land.