Morphologic analysis of Merapi edifice in studying Merapi-type eruption to improve volcanic hazard map

HARTINI, Komang Sri, Prof. Dr. Junun Sartohadi

2010 | Tesis | S2 Geo Informasi untuk Manajemen Bencana

Morphologic analysis was conducted to determine factors ascertain the direction of Merapi – type eruption (MTE) in the past and to utilize those factors in predicting direction and area likely affected by MTE in the near future. Proposed hazard zone for MTE was also developed to improve existing Merapi hazard map. As the quality of morphologic analysis is determined by DEM quality, the efficacy and accuracy assessment of input data were essential to conduct, through initial observation among DEMs, visual and statistical methods for IFSAR DEM. The study reveals that scale 1: 25,000 is appropriate to study morphology of vicinity area whilst scale 1.5,000 or even larger is needed to study morphology of summit area. The emerging of IFSAR technology is a promising technique to replace ground survey and passive photogrammetry, visual observation shows it delivers similar height distributions to reference DEM although it has less absolute vertical accuracy than product specification. Based on reconstruction of past time eruptions, crater breaching and its adjacent ridges are the main factors ascertain direction of MTE and shifting trends of west – southwest – southeast are also able to observe. Prediction in direction and area affected reveals almost 18,000 inhabitants of four villages in southern flank likely to be affected by MTE hazard in the near future. Proposed hazard zone discovers 1.42 km and 2.2 hectare in northern part (K. Apu) and as far as 0.43 km and 0.9 hectare area in southern part (K. Gendol) as extent distance and area to the forbidden zone of existing hazard map. Proposed hazard zone also gives detail of area and river probably channelized by pyroclastic flow hazard as improvement of existing hazard map, to finally provide effective mitigation plans and guidelines for long term landuse planning well as.

Kata Kunci : Merapi,type eruption (MTE),Morphologic analysis,Proposed pyroclastic flow hazard zone,Digital elevation models