**Author details**

Keiji Takemura1 , Tsuyoshi Haraguchi2 , Shigekazu Kusumoto3 and Yasuto Itoh4

1 Beppu Geothermal Research Laboratory, Institute for Geothermal Sciences, Graduate School of Science, Kyoto University, Noguchibaru, Beppu, Japan

2 Graduate School of Science, Osaka City University, Osaka, Japan

3 Graduate School of Science and Engineering for Research, University of Toyama, Toyama, Japan

4 Graduate School of Science, Osaka Prefecture University, Osaka, Japan
