Bulletin of the Geological Society of Malaysia, Volume 43, Dec. 1999, pp. 205 – 213
Volcanological Survey of Indonesia, JI. Diponegoro 57, Bandung 40122, Indonesia
Abstract: Indonesia is a wide archipelago where 129 active volcanoes are located. It means that about 13% of active volcanoes all over the world are located in the Indonesian archipelago. The volcanoes are located along the 7,000 km tectonic belt through Sumatera, Java, Nusa Tenggara, North Sulawesi, North Maluku, up to South Maluku. About 10% of the Indonesian population live in the dangerous volcanic areas. In the last 300 years, some 175 thousands people were killed by volcanic eruptions in Indonesia.
The volcanic hazard mitigation is carried out technically by the Volcanological Survey of Indonesia which is unified in the National Coordination Agency for Disaster Management. One of the programs carried out is Volcanic Hazard Mapping. The Volcanic Hazard Map is one identifying the degree of volcanic hazard in an area. It is used as a guidance for evacuation purposes when the volcano is in eruption or in increasing activity.
Determination of volcanic hazard zones can be divided into three levels of hazard zone where from the highest to the lowest are hazard zone III, hazard zone II, and hazard zone I, respectively. The Hazard Zone III is a zone which is very frequently affected by pyroclastic flow, lava flow, glowing rock fall, and poisonous gas, such as Mt. Semeru (East Java) and Mt. Merapi (Central Java). The Hazard Zone II is a zone which is potentially affected by pyroclastic flow, lava flow, ejected glowing rock, heavy ash fall, hot mud falls, lahar flow and poisonous gas. The Hazard Zone I is a zone which is potentially affected by lahar or flood and it still possible to be affected by an expanded pyroclastic flow and lava flow.
The three levels of the hazard zonation is applicable on the very active volcanoes, which erupts very frequently. This is supported by a lot of data about them and consequently, the character of the volcanoes can mostly be recognized. In fact, many other active volcanoes have very limited supporting data. In case of development of volcanic resources or that of developing an area especially on volcanoes area which have poor reference data, a detailed study of volcanic hazard assessment on the area is required to be done in the feasibility study.
The Volcanic Hazard Map can be utilized firstly as a guide for evacuating people when the volcano is erupting, secondly as one of the main references for Regional Planning, and thirdly, for early warning system.