抄録
Mayon Volcano, 330 km southeast of Manila on the island of Luzon, is a classic composite cone of andesite and basaltic andesite lavas and pyroclastics. The historical eruptions of Mayon occurred 45 times since 1616 till September 1993.
In 2 February 1993, Mayon erupted with minor pyroclastic flow which descended along the Bonga gully at the southern sector of the edifice. The area within the previously declared 6 km permanent danger zone was badly hit with 77 human casualties by this event. Smaller pyroclastic flows followed several days after the first eruption also utilizing the Bonga gully. Secondary lahars triggered by tropical rainfalls were also generated after the eruption. About 60, 000 people living within 10 km on the sooutheast side of the volcano has been evacuated. After the disaster, a relocation/resettlement plan was drawn up as a part of Integrated Rehabilitation Project. Many evacuated people, however, have already returned to “barangays” even in the danger zone.
Topographic conditions on the southeastern slopes of the volcano, especially along the Bonga gully, were considerably changed and some sabo structures reduced their effects in controlling sediment movement so that forthcoming rainfall might generate disasters by movement of remaining volume of debris.
After conducting a field reconnaissance and rapid appraisal, we have made some considerations on structural measures for sediment control, non structural measures as data acquisition and early warning system, and integrated regional development as a measure for revealing disaster resilient society.
