HR: 16:00h
AN: V24B-01 INVITED     [Abstracts]
TI: Overview and the achievement of the Unzen Scientific Drilling Project
AU: * UTO, K
EM: k.uto@aist.go.jp
AF: Geological Survey of JAPAN, AIST, 1-1-1 Higashi, Tsukuba, 305-8567 Japan
AU: NAKADA, S
EM: nakada@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, Univ. Tokyo, Yayoi, Bunkyo-ku, Tokyo, 113-032 Japan
AU: SHIMIZU, H
EM: shimizu@sevo.kyushu-u.ac.jp
AF: Institute of Seismology and Volcanology, Kyushu Univ., Shinzan, Shimabara, 855-0843 Japan
AU: SAKUMA, S
EM: sakuma@geothermal.co.jp
AF: Japan Metals & Chemicals Co., Ltd., Ukai, Takizawa, 020-0172 Japan
AU: HOSHIZUMI, H
EM: h.hoshizumi@aist.go.jp
AF: Geological Survey of JAPAN, AIST, 1-1-1 Higashi, Tsukuba, 305-8567 Japan
AB: Unzen volcano is an active volcano in SW Japan, and its 1990-95 eruption caused the frequent dome-collapse-type pyroclastic flows and associated debris flows. Detailed observations have enabled the constructions of magma ascent and eruption models. Unzen was born in 0.5 Ma and has grown inside the regional tectonic graben. Most of its eruption products have been thickly accumulated inside the active graben more than 1200 m beneath the current surface. Unzen Scientific Drilling Project (USDP) is a six-year term international project started in April 1999, co-sponsored by the Japanese Government and International Continental Scientific Drilling Program. The project includes not only scientific drillings but also related geological, geophysical and geochemical studies to totally understand the growth history, subsurface structure and magma ascending mechanism of Unzen Volcano. The highlight of USDP is to drill into the still-hot magmatic conduit of 1990-95 eruption (conduit drilling) to prove the magma ascent model based on detailed observations during the eruption, and is scheduled during the Phase II (2002-2005) of the project. Phase I of USDP (1999-2002) consists of drilling two boreholes (USDP-1: 752 m and USDP-2: 1462 m) into the flanks of Unzen Volcano and conducting associated researches mainly to reveal the time-integrated process of Unzen volcano; i.e. three-dimensional structure and the growth history of the volcano. Pilot drilling (USDP-3, 350m) associated with the scientific and drilling strategy for the conduit drilling was also conducted. Following the scientific results of Phase I, Phase II was approved by the funding agency and the conduit drilling started in February 2003. Repeated troubles necessitated some modifications of the drilling plan, but the drilling was successfully ended in July 2004 by penetrating into the 1990-95 magmatic path about 1500m beneath the summit of Unzen volcano. Construction of an integrated evolutional and magmatic model of Unzen will be the final goal combining all scientific results in the end of the project.
DE: 8414 Eruption mechanisms
DE: 8439 Physics and chemistry of magma bodies
DE: 3640 Igneous petrology
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2004 AGU Fall Meeting