shallow magma plumbing system at Rabaul caldera, Papua new Guinea

Research Project

Project/Area Number	13573002
Research Category	Grant-in-Aid for Scientific Research (B)
Allocation Type	Single-year Grants
Section	海外学術
Research Field	固体地球物理学
Research Institution	Hokkaido University
Principal Investigator	NISHIMURA Yuichi Hokkaido University, Graduate School of Science, assistant (20208226)
Co-Investigator(Kenkyū-buntansha)	SHIMAMURA Hideki 北海道大学, Graduate School of Science, professor (10011636) NAKAGAWA Mitsuhiro 北海道大学, Graduate School of Science, assistant (50217684) OBA Takeshi 東京工業大学, Volcanic Flurd Research Center Tokyo Institute of Technology, assostant professor (60203915) NOGAMI Kenji 東京工業大学, Volcanic Flurd Research Center Tokyo Institute of Technology, assistant (70251676)
Project Period (FY)	2001 – 2003
Project Status	Completed (Fiscal Year 2003)
Budget Amount *help	¥8,000,000 (Direct Cost: ¥8,000,000) Fiscal Year 2003: ¥2,000,000 (Direct Cost: ¥2,000,000) Fiscal Year 2002: ¥3,800,000 (Direct Cost: ¥3,800,000) Fiscal Year 2001: ¥2,200,000 (Direct Cost: ¥2,200,000)
Keywords	Rabaul / eruption / magma chamber / tsunami / volcanic gas / volcanic ash / eruption history / monitoring volcanic acivity / ラバウルカルデラ / マグマ供給系 / 火山性津波 / 火山岩石学 / 土壌ガス / 火山灰付着水溶性成分 / 火山活動 / カルデラ / 火山噴火予知 / 地球化学 / 噴火災害
Research Abstract	In order to investigate the magma system of this Rabaul caldera and to evaluate the recent activities of the volcanoes, an international scientific research project was performed from 2001 to 2003. During 2001-2003, Japanese team visited Rabaul three times and made cooperative observations with the Rabaul volcanological Observatory (RVO). In 2001, we clarified basic chronology for tephras from 1994 and some historical eruptions and collect rock samples for further chemical analyses. Geochemical surveys were carried out in 2002 and 2003. Fumarolic gases and hot spring water were samples on the foot of Tavurvur Volcano. C02 flux from ground surface were measured repeatedly around Simpson harbor in order to evaluate spacial distribution of the anomaly and monitor the magma activity. During our survey in 2002 and 2003, Tavurvur emitted ash with Vulcanian eruptions and small explosions that occurred frequently. Chemical analysis of water leachates of the ash was useful for remote monitoring of the volcano. Tsunami deposits caused by the 1994 eruptions were identified as sand layers or characteristic pumiceous sand layers sandwiched by tephras from both Vulcan and Tavurvur Volcanoes. The chronological studies of both tephra and tsunami deposits was done to reveal the tsunamigenic volcanic process in the 1994 eruption series.