TY  - JOUR
ID  - epos1308
UR  - http://dx.doi.org/10.1186/BF03352963
IS  - 10
A1  - Yabe, Yasuo
A1  - Philipp, Joachim
A1  - Nakatani, Masao
A1  - Morema, Gilbert
A1  - Naoi, Makoto
A1  - Kawakata, Hironori
A1  - Igarashi, Toshihiro
A1  - Dresen, Georg
A1  - Ogasawara, Hiroshi
N2  - 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.
VL  - 61
TI  - Observation of numerous aftershocks of an M w 1.9 earthquake with an AE network installed in a deep gold mine in South Africa
AV  - none
EP  - e52
Y1  - 2009/11//
PB  - Terra Scientific Publishing Company
JF  - Earth, Planets and Space
KW  - Semi-controlled earthquake generation experiment
KW  -          acoustic emission
KW  -  mining-induced earthquake
KW  -  deep South African gold mines
        aftershocks
        main shock rupture plane
SN  - 1343-8832
SP  - e49
ER  -