TY  - JOUR
ID  - epos1385
UR  - http://dx.doi.org/10.1029/2006GL026507
IS  - 12
A1  - Naoi, Makoto
A1  - Ogasawara, Hiroshi
A1  - Takeuchi, Junichi
A1  - Yamamoto, Akihito
A1  - Shimoda, Naoyuki
A1  - Morishita, Ken
A1  - Ishii, Hiroshi
A1  - Nakao, Shigeru
A1  - van Aswegen, Gerrie
A1  - Mendecki, Aleksander J.
A1  - Lenegan, Patrick
A1  - Ebrahim-Trollope, Rookshana
A1  - Iio, Yoshihisa
Y1  - 2006/04//
N2  - The Research Group for Semi-controlled Earthquake-generation Experiments in South African deep gold mines (SeeSA) has continuously monitored strain changes with a resolution of 24 bit 25 Hz at the Bambanani mine near Welkom. An Ishii borehole strainmeter was installed at a depth of 2.4 km near the potential M ? 3 earthquake source area. Instantaneous strain steps of ?10^?4 strains associated with two M2 events were observed within a length of seismic fault. These steps were followed by significant post-seismic creep-like drift, but not preceded by forerunners. Analysis of the continuous 25 Hz data reveals many smaller steps with much longer durations (100 ms ? 100 s) than seen in normal earthquakes (?1 < M < 2) with source durations of 1 ms?50 ms. Some of the especially slow steps were preceded by accelerations in strain, the maximum being as large as one-third of the step.
PB  - Wiley
JF  - Geophysical Research Letters
VL  - 33
SN  - 0094-8276
TI  - Small slow-strain steps and their forerunners observed in gold mine in South Africa
AV  - none
ER  -