@article{epos1308,
          volume = {61},
          number = {10},
           month = {November},
          author = {Yasuo Yabe and Joachim Philipp and Masao Nakatani and Gilbert Morema and Makoto Naoi and Hironori Kawakata and Toshihiro Igarashi and Georg Dresen and Hiroshi Ogasawara},
           title = {Observation of numerous aftershocks of an M w 1.9 earthquake with an AE network installed in a deep gold mine in South Africa},
       publisher = {Terra Scientific Publishing Company},
            year = {2009},
         journal = {Earth, Planets and Space},
           pages = {e49--e52},
        keywords = {Semi-controlled earthquake generation experiment,         acoustic emission, mining-induced earthquake, deep South African gold mines
        aftershocks
        main shock rupture plane},
             url = {https://episodesplatform.eu/eprints/1308/},
        abstract = {This is the first report from the JAGUARS (JApanese-German Underground Acoustic Emission Research in South Africa) project, the overall aim of which is to observe ultra-small fracturing in a more or less natural environment. We installed a local ({$\sim$}40-m span) network of eight acoustic emission (AE) sensors, which have the capability to observe up to 200 kHz at a depth of 3.3 km in a South African gold mine. Our specific objective was to monitor a 30-m thick dyke that remains as a dip pillar against active mining {$\sim$}90 m above our network. An M w 1.9 earthquake whose hypocenter was {$\sim$}30 m above the network occurred in the dyke. Although the mineowned geophone (4.5 Hz) network detected only five earthquakes in the surrounding 200{$\times$}200{$\times$}150-m3 volume within the first 150 h following the main shock, our AE network detected more than 20,000 earthquakes in the same period. More than 13,000 of these formed a distinct planar cluster ({$\sim$}100{$\times$}80 m2) on which the main shock hypocenter lay, suggesting that this cluster delineates the main shock rupture plane. Most of the aftershocks were presumably very small, probably as low as M {$\sim$} ?4. The aftershock cluster dipped {$\sim$}60?. This is consistent with normal faulting under a nearly vertical compression field, as indicated by nearly horizontal breakouts found in a borehole crossing the rupture plane.}
}