Volcanic Hazard Assesment in Geothermal Area

Abstract

Tectonically, most of the Indonesian geothermal areas are located in active volcanic region. The volcanoes may erupt violently causing damages to the power plant site and energy production. In order to minimize loss of live and property damages it is proposed to assess volcanic hazards in geothermal areas. The first step of this study is to collect available information on volcanic phenomena and the rocks in the region. The volcanic phenomena consist of ballistic projectiles, pyroclastic ash-falls, flows, and surges, lava flows, debris avalanches, lahars etc. The result of the data analyses can be used to decide whether a volcanic hazard evaluation is required or not. If it does, it requires identification of all volcanic hazard sources. Data analysis using conservative deterministic evaluation of the effects of volcanic hazard phenomena will yield a screening distance value. If the site is located inside the screening distance value(s), the effects of a particular volcanic hazard must be evaluated. In case the area has historical or Holocene capable volcanic source, Deterministic Evaluation Method is used, or otherwise, Probabilistic Evaluation Method is used when the area has only Pre Holocene capable volcanic source. The result of the evaluation will yield a decision whether the site is accepted or is rejected. When the analysis gives a decision to accept the site, an engineering design base for geothermal power plant construction is derived.