|Title:||Small slow-strain steps and their forerunners observed in gold mine in South Africa|
|Authors:||Naoi, Makoto https://orcid.org/0000-0001-9488-9266 (unconfirmed)|
van Aswegen, Gerrie
Mendecki, Aleksander J.
Iio, Yoshihisa https://orcid.org/0000-0003-0808-0757 (unconfirmed)
|Author's alias:||直井, 誠|
|Publisher:||American Geophysical Union|
|Journal title:||Geophysical Research Letters|
|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.|
|Rights:||© 2006 by the American Geophysical Union|
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|Appears in Collections:||Journal Articles|
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