Research on earthquake preparation process - Accomplishment of observation networks installed very close to earthquake sources in South Africa gold mines -

地震准备过程研究 - 完成在南非金矿靠近震源安装的观测网络 -

• 批准号: 14204040
• 负责人: IIO Yoshihisa
• 金额: $ 33.2万
• 依托单位: KYOTO UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2005
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-14204040/
• 关键词: Earthquake preparation process; fault; South Africa; Induced earthquake; Strainmeter; Rock burst; gold mine; Mine tremor

By analyzing data from the accelerometer array installed at a depth of 2.6 km at the Mponeng mine in South Africa, we confirmed that the similarity law holds for mine tremors (-2<M<3). Further, by an inversion of rupture process of mine tremors that occurred within 100m from the array, we found that their slip distributions are as heterogeneous as those of natural large earthquakes, and that their rupture velocities and seismic efficiencies are also similar to those. We extensively analyzed data from the Ishii-type strainmeter installed at a depth of 2.4 km at the Bambanani mine and detected strain changes related to M2 class tremors and their foreshock and aftershocks that occurred within 100m from the strainmeter. No anomalous strain changes just before the M2 class tremors, however, were seen before the tremors, in spite of their large strain step of about 10-4. By utilizing these strain step records, we precisely determined hypocentral locations. We inferred from these data that th … More e M2 class tremors preceded by foreshocks occurred on a geological fault but that events without foreshocks occurred in the dyke around the fault tip. We detected strain steps for small tremors that were not detected by the mine seismic network These steps were followed by significant post-seismic creep-like drift, but not preceded by forerunners. Analysis of the continuous 25Hz data reveals many smaller steps with much longer durations (100ms-100s) than seen in normal earthquakes (-1<M<2) with source durations of 1ms〜50ms. Some of the especially slow steps were preceded by accelerations in strain, the maximum being as large as one-third of the step. We installed straimneters and accelerometers near the Pretorius fault at a depth of 2.9 km in the Mponeng mine. We observed strain changes generated by M2 class tremors that occurred within a few hundreds meter from the strainmeters. Similar strain changes were recorded by the two strainmeters. We observed a strain step of 10-5 at maximum but no forerunner was recorded for such a large strain step. Less

通过分析安装在南非Mponeng矿2.6 km深处的加速度计阵列的数据，我们证实了相似律适用于矿震（-2<M<3）。此外，通过对台阵100 m范围内矿震破裂过程的反演，发现它们的滑动分布与天然大震一样不均匀，破裂速度和地震效率也与天然大震相似。我们广泛分析了安装在Bambanani矿2.4 km深处的石井型应变仪的数据，并检测了与M2级地震及其前震和余震相关的应变变化，这些地震发生在距离应变仪100 m的范围内。然而，在M2级地震之前没有看到异常应变变化，尽管它们的应变步长约为10-4。利用这些应变阶跃记录，我们精确地确定了震源位置。我们从这些数据推断， ...更多信息 e在前震之前的M2级地震发生在地质断层上，但没有前震的地震发生在断层尖端周围的堤坝上。我们检测到的小震动，没有检测到的矿山地震网络的应变步骤，这些步骤之后是显着的震后蠕变样漂移，但没有之前的前兆。对连续25 Hz数据的分析显示，与震源持续时间为1 ms-50 ms的正常地震（-1<M<2）相比，有许多持续时间更长（100 ms-100 s）的较小台阶。有些特别缓慢的步骤之前，在应变的加速，最大的是作为一个步骤的三分之一大。我们在Mponeng矿2.9公里深处的Pretorius断层附近安装了应变计和加速度计。我们观察到在距离应变仪几百米范围内发生的M2级地震产生的应变变化。两种应变仪记录到的应变变化相似。我们观察到最大10-5的应变阶跃，但没有记录到如此大的应变阶跃的先导。少

项目成果

Near source observation of small initial phase generated by earthquakes in a deep gold mine in South Africa

南非深部金矿地震产生的小初相的近源观测

• 发表时间: 2002
• 期刊: Seismogenic Process Monitoring (Ogasawara et al. eds.), Balkema
• 作者: Satoh;T.;et al.
• 通讯作者: et al.

Multidisciplinary Monitoring of the Entre Life Span of an Earthquake and its Practical Strategy in South African Gold Mines.

南非金矿地震整个生命周期的多学科监测及其实用策略。

• 发表时间: 2005
• 期刊: Proceeding of the 6th International Symposium on Rockburst and Seismicity in Mines
• 作者: Ogasawara;H.;et al.
• 通讯作者: et al.

High-resolution Strain Monitoring During M〜2 Events in a South African Deep Gold Mine in Close Proximity to Hypocentres

南非深部金矿中紧邻震源的 M〜2 事件期间的高分辨率应变监测

• 发表时间: 2005
• 期刊: Proceedings of the 6th International Symposium on Rockburst and Seismicity in Mines
• 作者: Ogasawara;H.;et al.
• 通讯作者: et al.

High-resolution Strain Monitoring During M 2 Events in a South African Deep Gold Mine in Close Proximity to Hypocenters.

在靠近震源的南非深金矿 M 2 事件期间进行高分辨率应变监测。

• 发表时间: 2005
• 期刊: Proceedings of the 6th International Symposium on Rockburst and Seismicity in Mines
• 作者: Ogasawara;H.;Takeuchi;J.;Shimoda N.;Ishii;H.;Nakao;S.;van Aswegen;G;Mendecki;A.J.;Cichowicz;A.Ebrahim-Trollope;R.;Kawakata;H.;Iio Y.;Ohkura;T.;Ando;M;the Research Group for Semi-controlled Earthquake-generation Experiments in South
• 通讯作者: the Research Group for Semi-controlled Earthquake-generation Experiments in South

M4.6地震の震源(南アフリカMathabeng金鉱山)

M4.6地震震中（南非Mathabeng金矿）

• 发表时间: 2004
• 期刊: 地質ニュース 第597号
• 作者: 朝治啓三;Shinichi Nagao;小笠原宏
• 通讯作者: 小笠原宏