U.S.-Japan Cooperative Science: Transient Electromagnetic Field Generation on Active Volcanoes-A Comparative Study of the Response from Long Valley Caldera and Aso Volcano, Japan

0003706约翰斯顿该奖项支持加州门洛帕克地质调查局的马尔科姆约翰斯顿教授和日本京都大学的田中义和教授之间为期三年的合作研究项目。 研究人员将对活火山产生的瞬变电磁场进行研究：比较加州的长谷火山口和日本的阿索火山的反应。 火山上电场和磁场的产生及其与应力、热量、流体和气体在火山过程中的作用之间的关系，是长期以来一直没有答案的基本问题，因为关于活火山的数据很少，对所涉及的过程也缺乏了解。 他们将把对阿索、云仙和长谷活火山的观察与对自电势产生的理论和实验室测量结合起来，以提供对数据含义的一些理解。 然后，他们将分离使这些数据的解释复杂化的过程，并调查这些数据对火山过程监测的实际影响。 特别是，他们希望确定产生自势异常所涉及的物理学。 他们希望表明，在足够高的温度下产生气相的自电势的主要贡献来自与气体相关的电荷传输过程。 在较低的温度下，主要的贡献是从电动效应调制的海拔效应。 然后，研究人员将在火山地区以及没有火山活动但已知地下流体流动的地区进行实地实验，量化最后两种影响。 该项目汇集了两个具有互补专业知识和研究能力的实验室的努力。 研究结果的影响，主动堤坝和岩床的检测，更重要的是，入侵活动的变化检测。 本研究通过研究生的参与促进国际人力资源。 通过交流思想和技术，该项目将扩大我们的基础知识，促进国际理解与合作。 研究人员计划在科学期刊上发表研究结果，并在科学会议上报告研究结果。

0003706JohnstonThis award supports a three-year collaborative research project between Professor Malcolm Johnston of the Geological Survey in Menlo Park, California and Professor Yoshikazu Tanaka at Kyoto University in Japan. The researchers will be undertaking a study of the transient electromagnetic field generation on active volcanoes: a comparison of the response from Long Valley Caldera in California and the Aso volcano in Japan. The generation of electric and magnetic fields on volcanoes and the relation these have to the role of stress, heat, fluids and gases in volcano processes are fundamental questions that have long gone unanswered because little data is available on active volcanoes and there is a poor understanding of the processes involved. They will bring together the observations on Aso, Unzen and Long Valley's active volcanoes with theoretical and laboratory measurements on self potential generation to provide some understanding on what the data means. They will then separate processes that complicate interpretation of these data and investigate the practical implications that these data have for volcano process monitoring. In particular, they hope to identify the physics involved in generation of self-potential anomalies. They expect to show that the primary contribution to self-potential at temperatures high enough to generate a gas phase arises from gas-related charge transport processes. At lower temperatures, the primary contribution is from electrokinetic effects modulated by elevation effects. The researchers will then quantify these last two effects in field experiments at volcanic areas and also in regions where no volcanic activity has occurred, but known subsurface fluid flow occurs. The project brings together the efforts of two laboratories that have complementary expertise and research capabilities. Results of the research has implications for the detection of active dikes and sills and, more importantly, for detection of changes in intrusion activity. This research advances international human resources through the participation of graduate students. Through the exchange of ideas and technology, this project will broaden our base of basic knowledge and promote international understanding and cooperation. The researchers plan to publish results of the research in scientific journals and report on the findings at scientific meetings.