The 1991 Mt. Pinatubo Eruption and the Aetas of the Philippines - Case Study Example

 Natural disasters cause tremendous impact on human lives, properties and the environment. Disasters happen in the most unexpected place and time. Thousands of lives are lost due to major disasters: natural and man-made. Some natural disasters increase in frequency and severity due to changes in demographic factors and utilization of environmental resources. Aside from the loss of lives and properties, disasters pose grave hazards to the environment. The U.S. Geological Survey, one of the agencies that closely monitored the event averred that “the second-largest volcanic eruption of this century, and by far the largest eruption to affect a densely populated area, occurred at Mount Pinatubo in the Philippines on June 15, 1991.” (Newhall, Hendley & Stauffer, 1997, 1) Its damage had been so widely extensive that is a case study in perspective. This essay is hereby written with the objective of proffering the eruption of one of the most controversial volcanoes of the century, Mt. Pinatubo in the Philippines. Figure 1. Mt. Pinatubo In Fury (PHILVOCS, 1996, 30) A brief overview of the historical eruption would be stated; followed by a sequence of events. The causes and effects of the eruption would likewise be presented. Any remedial action would be assessed in terms of the possibility of minimizing the destructive impact of the disaster. Overview of the Eruption Mt. Pinatubo is located in Zambales, one of the provinces in the island of Luzon. It has been home to the Aetas, a semi-nomadic Negrito tribe indigenous in the Philippines. Gaillard (2006, 6) identified the Aetas “are found on the flanks of Mt. Pinatubo which towers at the apex of the provinces of Pampanga, Tarlac and Zambales on the main island of Luzon.” According to the Philippine Institute of Volcanology and Seismology (PHILVOCS), “as early as 7 million years ago, the eruptive activity of the Zambales range had already begun. This lasted for millions of years, subsiding only 450 years ago.” (1996, 3) Mt. Pinatubo had been classified as an inactive volcano prior to its eruption due to its inactivity almost five centuries ago. The unexpected stir surprised the whole population of Luzon, most especially since the area beside the volcano is densely populated. The disastrous eruption was so violent that it released “more than 5 billion cubic meters of ash and pyroclastic debris were ejected from its fiery bowels producing eruption columns 18 kilometers wide at the base and heights reaching up to 30 kilometers above the volcano’s vent.” (PHILVOCS, 1996, 10) The extent of its impact was not confined to the local scene but reached as far as North America and Russia (PHILVOCS, 1996, 12) and widened the hole in the earth’s ozone layer. Figure 2. Extent of ash cloud from the June 15, 1991 eruption. Newhall, Hendley & Stauffer (1997, 2) Sequence of Events Only two months prior to the major eruption of Mt. Pinatubo, a hydrothermal explosion seen as steam of clouds and ash shooting from active vents were ejected to as high as 500 to 800 meters. This event prompted the official agency in charge of volcanic activities, the PHILVOCS, to install seismic station near the area to monitor the volcanic activity. High frequency volcanic quakes started to intensify in frequency and duration. This continued from its original active state on April until progressing to harmonic tremors in June. Harmonic tremors indicate an intensification of seismic activity within Mt. Pinatubo. The first ash ejection was seen on June 3, 1991 lasting for about 30 minutes. Intermittent subsequent ash ejections occurred until a dome was formed on the summit of the volcano by the end of the first week of June. “The dome was formed by sticky lava that reached the surface.” (PHILVOCS, 1996, 25) Figure 3. April 2, 1991 steam emitted (PHILVOCS, 1996, 29) The early hours of June 9, 1991 displayed the remarkable explosion of ash-laden steam clouds, followed by pyroclastic flows into the Maraunot and Moraza rivers. Pyroclastic flows are turbulent flowing mass of ejected fragmental volcanic materials mixed with hot gases and moving down slope at high speed (about 60 kph or more). (PHILVOCS, 1996, 30) On June 12, the Philippine’s Independence Day signaled Mt. Pinatubo’s fury through a series of major volcanic eruptions showing “huge, grey, mushroom-shaped cloud" reaching 20 kilometers into the air. These series of major explosions lasted continuously for a little over a week. Figure 4. June 12 Huge Grey Mushroom Cloud (PHILVOCS, 1996, 30) The USGS (Newhall, et.al., 1997, 4) stipulated that “a blanket of volcanic ash (sand- and silt-size grains of volcanic minerals and glass) and larger pumice lapilli (frothy pebbles) blanketed the countryside. Fine ash fell as far away as the Indian Ocean, and satellites tracked the ash cloud several times around the globe.” Figure 5. June 13 Major Eruptions (PHILVOCS, 1996, 31) Causes and Effects of the Eruption Volcanoes erupt due to three major factors. According to Kilinc (1999, 1), “the buoyancy of the magma, the pressure from the exsolved gases in the magma and the injection of a new batch of magma into an already filled magma chamber” trigger a volcano’s explosion. In the case of Mt. Pinatubo, these three predominant factors concurrently existed and prompted the previously inactive volcano to explode. The unique feature of Mt. Pinatubo’s eruption is that it is a classic example where scientists were able to predict, through forecasting tools and parameters, the timing of its disastrous explosion. Kilinc (1999, 7) averred that “volcanologists from the U.S. Geological Survey and PHILVOCS accurately predicted the June 15 eruption of the Pinatubo Volcano in the Philippines, allowing for the timely evacuation of the Clark Air Base and saving thousands of lives.” Figure 6. Lahar from Pinatubo (PHILVOCS, 1996, 40) Figure 7. Bridge Destroyed (PHILVOCS, 1996, 42) Figure8. Houses covered by Lahar (PHILVOCS, 1996, 42) Figure 9. Whole Community Covered by Lahar (PHILVOCS, 1996, 43) However, despite the accuracy of the prediction, the devastating effects of Mt. Pinatubo’s fury remained. The most eminent of the ill-effects of this natural disaster are as follows: (1) the loss of more than 847 lives, injuries totaling 184 individuals, 23 people missing, for a total affected 249,000 families numbering approximately 1.18 million people (PHILVOCS, 1996, 37); (2) loss amounting to one half of a billion dollars in property and economic damage (Rosenberg, 2007, par. 13); (3) depletion of the ozone layer due to the “15 and 30 million tons of sulfur dioxide gas. Sulfur dioxide in the atmosphere mixes with water and oxygen in the atmosphere to become sulfuric acid, which in turn triggers ozone depletion”. (Rosenberg, 2007, 9); (4) destruction of about 86,000 hectares of agricultural land and fishponds reverberating to lesser food production and higher prices of existing commodities; (5) roads, bridges and other infrastructures within the scope of the eruption were totally damaged necessitating traffic rerouting schemes and long term rebuilding and reconstructing strategies; (6) “structures on the two largest U.S. military bases in the Philippines--Clark Air Base and Subic Bay Naval Station--were heavily damaged” (Newhall, et.al., 1997, 8) resulting in the ultimate evacuation of the bases by the Americans; (7) world temperature declined due to the cloud covering the earth. According to Robock (2003, 6) “Pinatubo produced global cooling, but impacts work in both directions, so the benefits of Pinatubo from global cooling teach us about the negative impacts of anthropogenic global warming”; and (8) subsequent climatic events in other parts of the world were influenced by this disaster, specifically the floods along the Mississippi river and the drought in the Sahel region of Africa (Rosenberg, 2007, 11). As illustrated by Goddard, “ large volcanic eruptions shoot fine ash up to very high altitudes, which makes the upper atmosphere less transparent, allowing less sunlight (SW radiation) to reach the lower atmosphere.  This has a noticeable cooling effect on the lower atmosphere and the earth’s surface which can last for years, as can be seen in the figures below.  Note how the lower troposphere temperatures were depressed during periods when the atmospheric transmission was also depressed.” (2009, 1) Figure 10. Source: (Goddard, 2009, 1) Remedial Action Despite the enumerated ill effects of Mt. Pinatubo’s eruption, as previously mentioned, USGS was instrumental in minimizing the blow of this disaster through accurately predicting its occurrence. Scholars and scientists have long searched for methods and appropriate tools and instruments to forecast the exact occurrence of natural disasters to implement appropriate actions and prevent losses. The population within the surrounding Mt. Pinatubo area totals to about 1,000,000 people including 20,000 American military personnel housed in the two biggest American bases in the Philippines. According to forecasts, more than 5,000 people were immediately evacuated and thereby saved. All of the American servicemen and their dependents were evacuated prior to the deadly explosion. In addition to lives, millions of dollars in property were saved. “When aircraft and other equipment at the U.S. bases were flown to safe areas or covered, losses of at least $200 to 275 million were averted. Philippine and other commercial airlines prevented at least another $50 to 100 million in damage to aircraft by taking similar actions. Other commercial savings are harder to quantify but were probably less than $100 million, and there is no way to estimate the sentimental or monetary value of the personal property saved by families.” (Newhall, Hendley & Stauffer, 1997, 7). The report conducted by Newhall, et.al. revealed that the costs spent to forecast and develop the monitoring capabilities at Mt. Pinatubo amounted to about $56 million. When compared to the amount saved in terms of human casualties and properties, the savings in property alone reached $250 million and tagged a monetary value of $1 million per life. As can be deduced, the benefits of monitoring volcanic activity at Mt. Pinatubo far outweighed the costs associated in developing and maintaining it. Newhall, et.al. concluded that “the experience gained by scientists during Pinatubo's 1991 eruption crisis is being used by the USGS Volcano Hazards Program in the United States and by PHIVOLCS in the Philippines to better protect people's lives and property from the future volcanic eruptions that will inevitably occur.” (1997, 11) Despite the surprised awakening of the sleeping giant, the early volcanic and seismic signs provided enough time for the locals to prepare and monitor subsequent events that could have been more disastrous without investing in the right resources. Conclusion The eruption at Mt. Pinatubo was overshadowed by the largest volcanic eruption of the 20th century - the 1912 eruption of Katmai-Novarupta in Alaska. The lessons learned from Mt. Pinatubo are more relevant in terms of mankind’s capabilities to appropriately apply remedial actions to prevent the extensive disastrous loss of an enormity of lives, property and the environment. The experience exemplified by local and international groups monitoring volcanic activities is highly commendable for the benefits they accorded. It is true that disasters happen in the most unexpected place and time. With vigilance and the assistance of technology, the full impact of these natural disasters can be minimized. In addition, this situation proffered a critical example of people from different parts of the world joining hands to support those afflicted by the disaster. It is not just a matter of cataclysmic phenomenon that must be observed and viewed. The active and immediate participation of local government agencies in coordination with scientists and scholars from the U.S. Geological Survey and other parts of the globe enabled the casualties to be abated. People learn so much from experiences brought about by natural disasters. Inasmuch as these disasters cannot be prevented, their ill effects can be curtailed with awareness, vigilance and immediate action. Abstract The havoc that the eruption of Mt. Pinatubo did to lives, properties and the environment proffered relevant lessons for both scholars and the people who experienced it. At the onset of the events, local and foreign agencies monitored its developments which provided the necessary steps to instigate remedial action to minimize the destructive effects. The monitoring and accurate forecasting collaborately done by PHILVOCS and USGS enabled lives and millions of dollars in properties to be saved. The effects of Mt. Pinatubo’s fury has extensive influence on climate change, ozone depletion and other climatic events in other parts of the world. This natural hazard experience exemplified that people can minimize its destructive impact through the utilization to technology and immediate proactive and responsive action. References Gaillard, J. C. (2006). “Traditional Societies in the Face of Natural Hazards: The 1991 Mt. Pinatubo Eruption and the Aetas of the Philippines.” International Journal of Mass Emergencies and Disasters March 2006, Vol. 24, No. 1, pp. 5-43. Goddard, S. (2009). How did the El Chichon and Pinatubo volcanic eruptions affect global temperature records? Watts Up With That? Anthony Watts. Word Press, Inc. Kilinc, A. (29 Nov.1999). “What causes a volcano to erupt and how do scientists predict eruptions?” Scientific American Magazine. Scientific American, Inc. Newhall, C., Hendley II, J.W., & Stauffer, P.H. (1997). Benefits of Volcano Monitoring Far Outweigh Costs–The Case of Mount Pinatubo. U.S. Geological Survey (USGS) Fact Sheet 115- 97. Newhall, C., Hendley II, J.W., & Stauffer, P.H. (1997). The Cataclysmic 1991 Eruption of Mount Pinatubo, Philippines. U.S. Geological Survey (USGS) Fact Sheet 113 – 97. Philippine Institute of Volcanology and Seismology (PHILVOCS). (1996). Fire and mud: eruptions and lahars of Mt. Pinatubo, Philippines. Quezon City. Robock, A. (2003). Introduction: Mount Pinatubo as a Test of Climate Feedback Mechanisms. Department of Environmental Sciences, Rutgers University, New Brunswick, New Jersey. Rosenberg, M. (2007). Mount Pinatubo Eruption. New York Times Company. New York, USA. Figure 1. PHILVOCS, 1996, 30 Figure 2. Newhall, Hendley & Stauffer ,1997, 2 Figure 3. PHILVOCS, 1996, 29 Figure 4. PHILVOCS, 1996, 30 Figure 5. PHILVOCS, 1996, 31 Figure 6. PHILVOCS, 1996, 40 Figure 7. PHILVOCS, 1996, 42 Figure 8. PHILVOCS, 1996, 42 Figure 9. PHILVOCS, 1996, 43 Figure 10. Goddard, 2009, 1 Read More