Yabe, Yasuo and Philipp, Joachim and Nakatani, Masao and Morema, Gilbert and Naoi, Makoto and Kawakata, Hironori and Igarashi, Toshihiro and Dresen, Georg and Ogasawara, Hiroshi (2009) Observation of numerous aftershocks of an M w 1.9 earthquake with an AE network installed in a deep gold mine in South Africa. Earth, Planets and Space, 61 (10). e49-e52. DOI: https://doi.org/10.1186/BF03352963
Full text not available from this repository.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 (∼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 ∼90 m above our network. An M w 1.9 earthquake whose hypocenter was ∼30 m above the network occurred in the dyke. Although the mineowned geophone (4.5 Hz) network detected only five earthquakes in the surrounding 200×200×150-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 (∼100×80 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 ∼ −4. The aftershock cluster dipped ∼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.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | Semi-controlled earthquake generation experiment, acoustic emission, mining-induced earthquake, deep South African gold mines aftershocks main shock rupture plane |
| Subjects: | Region > RPA Inducing technology > Underground mining Methodology > Method and procesing |
| Project: | IS-EPOS project |