Siyanda Brightboy Mngadi, University of Witwatersrand, Wits, South Africa, Musa Siphiwe Manzi, University of Witwatersrand, School of Geosciences, Wits, South Africa, Raymond J Durrheim, University of the Witwatersrand, School of Geosciences, Johannesburg, South Africa, Akito Tsutsumi, Kyoto Univ, Kyoto, Japan, Yasuo Yabe, Tohoku University, Sendai, Japan, Hiroshi Ogasawara, Ritsumeikan University, Kusathu, Japan, Yuko Onoe, Kyoto University, Kyoto, Japan, Shunya Kaneki, Osaka University, Osaka, Japan, Neta Wechsler, Tel Aviv University, Department of Geophysics, Atmospheric and Planetary Sciences, Tel Aviv, Israel, Masao Nakatani, the University of Tokyo, Bunkyo, Japan, Makoto Naoi, Tokyo University, Tokyo, Japan and Hirokazu Moriya, Tohoku Univ, School of Engineering, Sendai, Japan