Disaster Management Best Practice

Pinatubo is a study case for best practices in immediate direct response preparedness for volcanic eruption. “The Mount Pinatubo 1991 eruption provides an excellent example of how accurate forecasting and timely warning system saved lives” (Tayag, 1997). The number of casualties was minimal in comparison with the violence of explosions and vastness of the area affected. The success of this preparedness is attributed to joint efforts of local people, grass-roots communities, and the Philippine Institute of Volcanology and Seismology (PHIVOLCS). Even though the conduction of this event is as a model for volcanic preparedness in the Philippines and other volcanic localities, surveys showed that there are still aspects to be improved especially in terms of establishing more fluid communication to reduce the number of casualties and property losses.

Eruption happened in June 1991. In the morning of June 15 Mount Pinatubo on the island of Luzon in the Philippines exploded in the largest volcanic eruption in more than three-quarters of a century (Newhall, 1997). This powerful eruption lasted ten hours and a cloud of ash rose as high as twenty-two miles into the air that could be seen from more than three hundred miles away. Before this cataclysmic eruption about one million people lived around Mount Pinatubo, including twenty thousand American military personnel. The U.S. Geological Survey (USGS) partnered with PHIVOLCS in the intensive monitoring of the mountain.

Communication between locals and officials helped identify the first signs of eruption. Indigenous Aetas, also known as Negritos, were the first to recognize the signs in April; however, preliminary earthquakes were felt around March 15 (Woo, 2008). The Aetas reported observations to PHIVOLCS through Sister Emma, a branch of the Franciscano Missionaries of Mary. Upon receipt of this information, PHIVOLCS, which had no monitoring system in Pinatubo, immediately began to monitor the mountain and, thenceforth, became the principle source of warnings. PHIVOLCS is the national entity tasked to study and monitor active volcanoes in the Philippines (Tayag, 1997).
Warning messages took form in different ways. Once PHIVOLCS officials started monitoring Mount Pinatubo they designed a warning system consisting of hazard zoning maps, alert levels, and “danger zones” -- areas of recommended evacuation. PHIVOLCS started disseminating maps on and after May 23. After first signs of small steam-blast explosions, PHIVOLCS soon declared a 10-kilometer radius danger zone around the volcano (Newhall, 1997). By the end of June 14, eighty-five thousand people -- including fourteen thousand and five hundred people from Clark Air Base -- had been relocated (Woo, 2008). In addition, daily bulletins and special advisory indicated alert levels associated with danger zones to be avoided and evacuated. Another important task of PHIVOLCS was translating and transmitting official messages to Disaster Coordination Councils (DCC) and local government officials.

The joint effort of PHIVOLCS and USGS saved lives and properties -- especially from Clark Air Military Base -- worth hundreds of millions of dollars by protecting them from damage and destruction. Scientists from both institutions spent US$ 1,5 million responding to Mount Pinatubo reawakening and forecasting, US$ 15 million in earlier efforts and US$ 40 million in evacuation, which prevented lives and property losses of at least US$ 250 million. The total cost of safeguarding lives and property were only about US$ 56 million, that is, one-fifth of the total cost if nothing had been done (Newhall, 1997). These calculus is the main rationale behind the “probalistic criteria” based on a cost-benefit argument which considered mainly the valuable mobile assets stationed at Clark Air Base. (Woo, 2008).

Non-governmental organizations played a central role in providing training for residents living around Mount Pinatubo prior to eruption. Local NGOs trained local leaders through workshops and taught them to identify a hazard, properly respond, and how to evacuate during the most critical time (Zschau, 2003). By educating and leveraging existing community network, NGOs managed to spread information efficiently and convince more easily local residents about the immediate need to evacuate and leave behind belongings and properties. Non-specialists tend to trust more on information passed on by relatives and scientists rather than local government and official newspapers (Houghton, 2011).

A survey was conducted in the aftermath of 1991 eruption to assess whether warnings were received, understood, and used by citizens to take protective action. According to this study 82% took protective action and 46% evacuated. The ones who did not evacuate alleged that they thought eruption would not be strong enough to affect their places; that they could not leave behind belongings, properties, livestock, and crops -- especially in harvest period; that they had no means of transportation to evacuate; and that local God would protect them (Tayag, 1997).

By conducting this survey, PHIVOLCS assessed four aspects of Pinatubo warning system. It not only identified the areas of success but also niches that needed improvement. This effort is part of “sharing performance information” to prevent the recurrence of adverse events that are likely to arise again (Donahue, 2006). A quick note, though, on the methodology of this survey. This was a stratified random sampling of two hundred thirty-four respondents who had lived in danger zones or areas recommended for evacuation – like barangays lying within forty kilometers of the volcano’s pre-eruption summit. Survey biases are mainly originated by interviewing only survivors and by also tending to be in favor of those who took precaution; however, resulting bias is deemed insignificant since it represented a very small percentage of the population at risk (Tayag, 1997). Respondents were household heads and adults, and key informants in barangays and municipal officials. Interviews were conducted by PHIVOLCS staff and local teachers who volunteered and also aided with scheduling and interpretation. The four areas assessed in this survey were source and timing, message, transmission, and recipients’ responses.

PHIVOLCS’s survey revealed the following findings. The most important that 71% of the respondents knew of the risks of the eruption before June 9, the date on which alert level five was issued. Before June 12, the date of the first large explosive events, 82% of the respondents knew of the danger. Also, official communication worked well since danger zones delineated by PHIVOLCS served as basis for the DCC’s issuance of evacuation orders (Tayag, 1998). The number of human losses was minimized -- about two to three hundred people -- because of perceptible signs from the volcano and prompt warning and mobilization of disaster-response officials. These findings “provided insights on how other volcano-eruption warning systems could be developed or improved” (Tayag, 1997). The study also showed that simultaneous transmission of warning was effective -- even though caused some confusion. Population living around Mount Pinatubo received information on the development of the eruption from multiple sources: DCC, major national and local newspaper, radio and TV stations, NGOs, and directly from relatives and PHIVOLCS officials. The drawback of this multipath warning transmission was the creation of some confusion, duplication, and overreaction. The survey suggested that these problems can be addressed by centralizing information in DCC.

Another interesting finding of 1991 survey is people’s responses to warning issues. “The warning, no matter how timely, accurate, and precise, will not be of any value unless the recipient of the warning takes appropriate defensive action” (Tayag, 1998). 81% of respondents who received forewarning alert took appropriate action by evacuating immediately or taking some other different action like preparation, convening meetings, and disseminating information. This survey suggested that the warning system worked well but some aspects could be improved since 18% had forewarned information but 34% of them took delayed and selective evacuation. The survey suggests that these numbers would be improved if local government had given special attention for the most vulnerable groups and developed strategies to convince the reluctant ones to evacuate even though they had to leave behind a harvest that would help them repay bank loans. The document also suggests that the warning communication system should reach out a larger area by radio and be careful about causing overreaction by providing specific and practicable information concerning the magnitude of the event -- the place at which it is expected and the time when it will occur.

The management of the Pinatubo volcano, therefore, “marks the highest point in the development of volcanic disaster mitigation in the Philippines” (Tayag, 1994). However, stakeholders still encountered some difficulties in communicating the magnitude and implications of geological hazards to non-specialists, who may have significant other pressures on them while making a decision as to what action to take, like the financial implications encountered by the military commander of the U.S. Clark Air Force Base who was only convinced to relocate after flying over the volcano (Forster, 2006). Besides communication, officials must address the controversy over adaptive and control approaches to disaster response machines. A combination of a monitoring-warning-evacuation system, relocation of settlements from the hazard zones, and the installation of engineering countermeasures to control and diverts lahar is the most effective and least costly mix alternative to protect lives and properties (Tayag, 1994). Another important aspect that should be improved is to understand people’s behavior in the face of volcanic threats. Volcanic risk perception has to be addressed by balancing non-hazard related factors and structural constraints. The choice of adjustments depends on how people perceive rare and extreme phenomena and the associated risk and people’s behavior in the face of natural hazards and constrained by social, economic, and political forces beyond their control (Gaillard, 2008).

References:

Donahue, Amy K.; Tuohy, Robert V. “Lessons We Don’t Learn.” Homeland Security Affairs, volume II, number 2, July 2006.

Forster, A.; Freeborough, K.; “A guide to the communication of geohazards information to the public.” British Geological Survey, Nottingham, 2006.

Gaillard, Jean-Christophe. “Alternative paradigms of volcanic risk perception: the case of Mt. Pinatubo in the Philippines.” Journal of Volcanology and Geothermal Research, volume 172, issues 3-4, pages 315-328, May 2008.

Houghton, Bruce. “Understanding Volcanoes and Coastal Hazards”. API Presentation in Honolulu, September 12, 2011.

Leone, Frederic; Gaillard, Jean-Christophe. “Analysis of the institutional and social responses to the eruption and the lahars of Mount Pinatubo volcano from 1991 to 1998.” Geojournal, volume 49, number 2, pages 223-238, July, 2006.

Newhall, Chris; Hendley II, James W.; Stauffer, Peter H. “Benefits of Volcano Monitoring Far Outweigh Costs – The Case of Mount Pinatubo.” U.S. Geological Survey Fact Sheet 115-97, 1997.

Surmieda, M R. “Surveillance in evacuation camps after the eruption of Mt. Pinatubo, Philippines.” MMWR CDC Surveill Summ, 41 (4): 9-12, August, 1992.

Tayag, Jean C.; Punongbayan, Raymundo S. “Volcanic Disaster Mitigation in the Philippines: Experience from Mt. Pinatubo”. Disasters, volume 18, issue 1, pages 1-15, March 1994.

Tayag, Jean; Insauriga, Sheila; Ringor, Anne; Belo, Mel. “People’s Response to Eruption Warning: The Pinatubo Experience 1991-1992.” Philippine Institute of Volcanology and Seismology, 1997.

Woo, Gordon. “Probalistic criteria for volcano evacuation decisions.” Natural Hazards, 45:87-97, 2008.

Zschau, Jochen; Kuppers, Andreas N. “Early warning systems for natural disaster reduction.” Springer-Verlag Berlin Heidelberg, 2003.