====Mount Pinatubo is an active stratovolcano located on the island of Luzon, near the tripoint of the Philippine provinces of Zambales, Tarlac, and Pampanga. It is located in the Cabusilan Mountains, separating the west coast of Luzon from the central plains. Before the volcanic activities of 1991, its eruptive history is unknown to most people. It was heavily eroded, inconspicuous and obscured from view. It was covered with dense forest which supported a population of several thousand indigenous people, the Aetas, who fled to the mountains during the Spanish conquest of the Philippines. ====

The volcano's Pilinian / Ultra-Plinian eruption on June 15, 1991 produced the second largest terrestrial eruption of the 20th century after the 1912 eruption of Novarupta in the Alaska Peninsular. Complicating the eruption was the arrival of Typhoon Yunya bringing a lethal mix of ash and rain. Successful predictions at the onset of the climactic eruption led to the evacuation of tens of thousands of people from the surrounding areas, saving many lives, but the surrounding areas were severely damaged by pyroclastic flows, ash deposits, and subsequently, by the lahars caused by rainwaters re-mobilizing earlier volcanic deposits destroying thousands of infrastructures and altering the river systems months to years after the eruption. Edit

Causes of the eruption

This eruption was caused because the Philippine plate subducted the Eurasian plate causing heat to build under Mount Pinatubo, and eventually rise rapidly due to release of pressure, causing the eruption to occur.

Mitigation methods

Disaster response Early warning and evacuation

Evacuation of the population at risk had been the concern of local authorities as early as April 1991 when the Philippine Institute of Volcanology and Seismology (PHIVOLCS) declared a 6-mile-radius danger zone around the volcano. PHIVOLCS, jointly with the U.S. Geological Survey (USGS), had conducted intensive studies and monitoring of the volcano’s activity from which it forecast and declared an imminent eruption and issued early warnings to the communities at risk. Among the first to have evacuated were the indigenous Aeta highlanders who had lived on the slopes of the volcano. About 20,000 in population, the Aetas had been safely evacuated before the eruption. People from the lowlands heeded also the warnings and fled to safer distance from the volcano. Also, more than 15,000 American servicemen and their dependents had evacuated from Clark Air Base before the eruption.

Immediate response

In the immediate aftermath of the eruption, the National Disaster Coordinating Council mobilized civilian and military resources to respond to the evacuation, rescue and relief requirements of the affected populations. Government agencies mobilized their respective facilities (hospitals, schools, etc.) and personnel (medical, social workers, teachers, etc.) to provide the necessary basic services in designated evacuation centers. The Department of Social Welfare and Development was in the forefront of providing emergency relief assistance to displaced families and victims in evacuation centers. The Department of Health led in the provision of medical care and public health services at evacuation centers, including disease surveillance. Heath advisories were also issued and broadcast to guide the public in coping with the ash fall as health hazard since the fine volcanic particles could cause sore eyes or trigger asthma.

Later on, a host of countries extended humanitarian relief assistance to the Philippine Government and its support NGO. International organizations such as WHO, UNDP, UNICEF, UNDRO and WFP also extended humanitarian relief assistance. The relief assistance was in the form of cash donations or relief items such as food packs, medicines, and shelter materials.

Recovery and reconstruction plan Development planning concerns

The government’s recovery and rehabilitation plan was guided by a development principle that rehabilitation and reconstruction should not be limited to restoration of destroyed or damages areas, facilities and systems to their original conditions but should address the vulnerabilities and deficiencies of previously existing conditions and mitigate any future disaster impact.

With the magnitude and extent of the destruction wrought by the eruption, development planners and policy-makers were confronted by the following concerns, which required immediate action as well as long-term solutions.

1) Resettlement. There was need to resettle people whose places of residence had been devastated and were beyond immediate reconstruction or had been damaged or affected and deemed unsafe for habitation. There were two target beneficiaries for resettlement: the indigenous Aeta highlanders and the displaced lowlanders. The resettlement strategy for the two groups had to differ to consider the variation in socio-cultural orientation and socio- economic activities of the Aetas and the lowlanders.

2) Livelihood. Government had to address the pressing concern of providing immediate and long-term, livelihood opportunities to displaced farmers and workers. Many farmlands had been unsuitable for agriculture and caused disruption of production of agriculture-based industries. The closure of Clark Air Base also presented the need for short-gestating livelihood opportunities and for alternative uses of base lands to cushion the effect of the massive displacement of workers.

3) Social Services. The continuing nature of the calamity had put pressure on social services sector to provide continued social services in terms of health, social welfare and education. Health and psycho-social services had to be extended to victims both in and outside the evacuation centers. The immediate opening of the classes and the extension of the school calendar had to be considered by the government at the same time that it was providing relief services to evacuees in school facilities. Social services would have to be extended in resettlement areas in order to prepare the resettlers for final resettlement.

4) Infrastructure. The eruption had caused massive destruction to the region’s roads and bridges, public buildings and facilities, communication, utilities and river and flood control structures. There was also need to institute disaster mitigation measures in view of the continuing threat of lahars and flashfloods.

5) Land use and environmental management. The effects of the eruption, especially lahar, continue to destroy farmlands, forest lands and watersheds and had caused damages to the river systems and overall environment of the region. This required careful physical land use re-planning of the region.

6) Science and Technology. The need to undertake scientific studies and formulate corresponding studies and policies was an evident concern and challenge for science and technology. The development of alternative uses of ash fall for commercial or industrial was an important concern for both government and the private sector.

In response to the above-mentioned concerns, the government vigorously pursued the following specific development objectives:

To mitigate further the destruction brought about by the adverse effects of the eruption, especially the lahars;

To normalize and accelerate economic recovery including the creation of an alternative investment climate;

To provide adequate livelihood and employment alternatives, especially for displaced farmers and workers;

To promote growth and development in resettlement and new settlement areas serving as alternatives to permanently damaged/ high-risk areas;

To ensure the continuous flow of goods and services, especially during relief operations when calamity strikes (lahars had made many areas inaccessible);

To strengthen institutional structures, arrangements, and mechanisms for disaster preparedness/ responsiveness and raise public awareness on disaster mitigation and reduction;

To reduce susceptibility of vertical and horizontal infrastructures to damages due to lahars and other disasters; and

To prevent further degradation of the environment and rehabilitate damaged ecosystems.

Impacts of eruption

Economic Impact

Damage to crops, infrastructure, and personal property totalled at least P10.1 billion ($US 374 million) in 1991, and an additional P1.9 billion ($US 69 million) in 1992. In addition, an estimated P454 million ($US 17 million) of business was foregone in 1991, and an additional P37 million ($US 1.4 million) in 1992. The destructions has slowed the economic improvement in the region and disrupted the momentum of growth. Further economic burden can be seen whereby construction of evacuation camps and relocation centers, was at least P2.5 billion ($US 93 million) in 1991-1992, and an additional P4.2 billion ($US 154 million).

Social Impact

Health. Morbidity and mortality rates increased mainly in evacuation centers. The leading diseases were acute respiratory infections (ARI), diarrhea, and measles (Department of Health, unpublished data, 1991). The death rate (Aetas and lowlanders combined) was 7 per 10,000 per week during 1991; that for Aetas in 1991 reached as high as 26 per 10,000 per week, and averaged 16 per 10,000 per week (Department of Health, 1992), and was especially high among Aeta children.

Social welfare. -The continuing threat of s had required that relief - food, clothing, shelter, and other help - be provided far beyond the period that is normal for typhoons and other calamities. As of October 28, 1993, approximately 1,309,000 people were being served outside evacuation centers. As of the same date, 159 evacuation centers were being maintained by the Department of Social Welfare and Development (DSWD) throughout Region III, housing some 11,455 families or 54,880 persons and providing them with food-for-work or cash-for-work assistance.

Education. About 700 school buildings with 4,700 classrooms were destroyed displacing an estimated 236,700 pupils and 7,009 teachers. Damage to school buildings was estimated to be P747 million as of August 1991 an amount that is growing with continuing lahar activity. Disruption of schooling was compounded by the use of undamaged school buildings as evacuation centers, which forced delays in the opening of classes and caused other disruptions of the school calendar. Initial damage to instructional materials, furniture, equipment, and other school supplies was estimated at P93 million pesos (Department of Education, Culture, and Sports, unpublished data, 1991).