Naoi, Makoto and Ogasawara, Hiroshi and Takeuchi, Junichi and Yamamoto, Akihito and Shimoda, Naoyuki and Morishita, Ken and Ishii, Hiroshi and Nakao, Shigeru and van Aswegen, Gerrie and Mendecki, Aleksander J. and Lenegan, Patrick and Ebrahim-Trollope, Rookshana and Iio, Yoshihisa (2006) Small slow-strain steps and their forerunners observed in gold mine in South Africa. Geophysical Research Letters, 33 (12). DOI: https://doi.org/10.1029/2006GL026507
Full text not available from this repository.Abstract
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.
| Item Type: | Article |
|---|---|
| Subjects: | Region > RPA Inducing technology > Underground mining Methodology > Method and procesing |
| Project: | IS-EPOS project |