Proposition d'une méthode d'évaluation et de cartographie des risques liés aux lahars sur le volcan Merapi (Java, Indonésie)

A proposal for assessing and mapping lahar-related hazard zones on the volcano Mount Merapi (central Java, Indonesia). About 440 000 people live at risk in areas prone to pyrodastic flows and lahars on the west and south flanks of the active stratovolcano Merapi. At least 23 major eruptions of the 61 reported eruptions since the mid- 1500's (V.S.I., 1990) have triggered lahars which killed about 7 000 people. The hazard-zone map of Merapi produced by the Volcanological Survey of Indonesia (1978) identifies three areas referred to as the forbidden zone, first danger zone and second danger zone, according to the different types of volcanic hazards. This map should now be revised, because its scale (1/100 000) lacks the detail necessary to accurately delimit the hazard zones, in particular valley channels likely to be swept by lahars. In addition, the map does not include social and economic factors which render people vulnerable and may lead to severe loss of life and property. Thus, a proposal is made for a combined appraisal and detailed mapping of hazard zones based on : (1) the characteristics, distribution, and sedimentology of recent deposits, and geometry of valley channels likely to be affected by lahars ; (2) social characteristics of people at risk

Geography · Geomorphology · Hazard map · Lahar · Pyroclastic rock · Seismology · Stratovolcano · Volcanic hazards · Volcano · Cryospheric studies and observations · Geology · Landslides and related hazards · Tree Root and Stability Studies