shallow magma plumbing system at Rabaul caldera, Papua new Guinea

为了研究拉包尔火山口的岩浆系统和评估火山的近期活动，从2001年到2003年进行了一项国际科学研究项目。2001-2003年，日本考察组三次访问拉包尔，并与拉包尔火山观测站（RVO）进行了合作观测。2001年，我们澄清了1994年的火山喷发和一些历史喷发的基本年代学，并收集了岩石样本进行进一步的化学分析。2002年和2003年进行了地球化学调查。Tavurvur火山脚下的火山气体和温泉水样本。为了评价异常的空间分布和监测岩浆活动，对辛普森港附近的地表co2通量进行了多次测量。在我们2002年和2003年的调查中，Tavurvur火山喷出的火山灰和频繁发生的小型爆炸。对火山灰渗滤液的化学分析对火山的远程监测很有用。1994年火山喷发引起的海啸沉积物被确定为砂层或由火神火山和塔武武尔火山的火山灰夹在中间的特征浮石砂层。通过对火山和海啸沉积物的年代学研究，揭示了1994年火山喷发系列中的海啸成因火山过程。

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.