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

• Project/Area Number: 14204040
• Research Category: Grant-in-Aid for Scientific Research (A)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 固体地球物理学
• Research Institution: KYOTO UNIVERSITY
• Principal Investigator: IIO Yoshihisa Kyoto University, DPRI, RCEP, Associate Professor, 防災研究所, 助教授 (50159547)
• Co-Investigator(Kenkyū-buntansha): OGASAWARA Hiroshi Ritsumeikan Univ., Fac. Sci. & Engr., Professor, 理工学部, 教授 (40213996) ; SATOH Takashi AIST Institute of Geology and Geoinformation, chief research fellow, 地質情報研究部門, 主任研究員 (90357161) ; KAWAKATA Hironori Ritsumeikan Univ., Fac. Sci. & Engr., Associate Professor, 理工学部, 助教授 (80346056) ; NAKAO Sigeru Kagoshima University, Faculty of Science, Associate Professor, 理学部, 助教授 (90237214) ; YAMAUCHI Tsuneo Nagoya Univ., Graduate School of Environmental Studies, Associate Professor, 大学院・環境学研究科, 助教授 (80022713)
• Project Period (FY): 2002 – 2005
• Project Status: Completed (Fiscal Year 2005)
• Budget Amount: ¥51,870,000 (Direct Cost: ¥39,900,000、Indirect Cost: ¥11,970,000); Fiscal Year 2005: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000); Fiscal Year 2004: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000); Fiscal Year 2003: ¥2,990,000 (Direct Cost: ¥2,300,000、Indirect Cost: ¥690,000); Fiscal Year 2002: ¥43,420,000 (Direct Cost: ¥33,400,000、Indirect Cost: ¥10,020,000)
• Keywords: Earthquake preparation process / fault / South Africa / Induced earthquake / Strainmeter / Rock burst / gold mine / Mine tremor

Research Abstract

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 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.

Research Products

• [Journal Article] Stress change prior to the major events in the 1989 earthquake swarm off the eastern Izu Peninsula, Japan (2006)
  • Author(s): Kawakata, H., et al.
  • Journal Title: Earth, Planets and Space Vol.58(No.3) Pages: 305-314
  • NAID: 10024491503
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Stress change prior to the major events in the 1989 earthquake swarm off the eastern Izu Peninsula, Japan (2006)
  • Author(s): Kawakata, H., Ogasawara, H., Sekiguchi, S., Uyama, S., Mino, K.
  • Journal Title: Earth Planets Space Vol.58 (No.3) Pages: 305-314
  • NAID: 10024491503
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Small slow-strain steps and their forerunners observed in gold mine in South Africa. (2006)
  • Author(s): Naoi, M., Ogasawara, H., Takeuchi, J., Yamamoto, A., Shimoda, N., Morishita, K, Ishii, H., Nakao, S., van Aswegen, G, Mendecki, A.J., Lenegan, P., Ebrahim-Trollope, R., Iio, Y.
  • Journal Title: Geophys.Res.Let. (accepted)
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Stress change prior to the major events in the 1989 earthquake swarm off the Eastern Izu Peninsula (2006)
  • Author(s): Kawakata, H., H.Ogasawara, S.Sekiguchi, S.Uyama, K.Mino
  • Journal Title: Earth, Planets and Space 58(in press)
• [Journal Article] Radiation efficiency and apparent stress of small earthquakes in a South African gold mine (2005)
  • Author(s): Yamada, T., et al.
  • Journal Title: J.Geophys.Res. Vol.101(B1)
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] High-resolution Strain Monitoring During M〜2 Events in a South African Deep Gold Mine in Close Proximity to Hypocentres (2005)
  • Author(s): Ogasawara, H., et al.
  • Journal Title: Proceedings of the 6th International Symposium on Rockburst and Seismicity in Mines Pages: 385-391
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Multidisciplinary Monitoring of the Entre Life Span of an Earthquake and its Practical Strategy in South African Gold Mines. (2005)
  • Author(s): Ogasawara, H., et al.
  • Journal Title: Proceeding of the 6th International Symposium on Rockburst and Seismicity in Mines Pages: 393-398
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Small slow-strain steps and their forerunners observed in gold mine in South Africa (2005)
  • Author(s): Naoi, M., et al.
  • Journal Title: Geophys.Res.Let (accepted)
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Radiation efficiency and apparent stress of small earthquakes in a South African gold mine. (2005)
  • Author(s): Yamada, T., Mori, J.J., Ide, S., Kawakata, H., Iio, Y., Ogasawara, H.
  • Journal Title: J.Geophys.Res. Vol.101(B1), 1305, doi : 10.1029/2004JB003221
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] High-resolution Strain Monitoring During M 2 Events in a South African Deep Gold Mine in Close Proximity to Hypocenters. (2005)
  • Author(s): 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 African deep gold mines
  • Journal Title: Proceedings of the 6th International Symposium on Rockburst and Seismicity in Mines Pages: 385-391
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Multidisciplinary Monitoring of the Entire Life Span of an Earthquake and its Practical Strategy in South African Gold Mines. (2005)
  • Author(s): Ogasawara, H., Takeuchi, J., Shimoda, N., Nakatani, M., Kato, A, Iio, Y., Kawakata, H., Yamada, T., Yamauchi, T., Ishii, H., Satoh, T., Kusunose, K., Otsuki, K., Kita, S., Nakao, S., Ward, A.K., McGrill, R., Murphy, S.K., Mendecki, A.J., van Aswegen, G, the Research Group for Semi-controlled Earthquake-generation Experiments in South African deep gold mines
  • Journal Title: Proceedings of the 6th International Symposium on Rockburst and Seismicity in Mines Pages: 393-398
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Radiation efficiency and apparent stress of small earthquakes in a South African gold mine (2005)
  • Author(s): Yamada, T., J.J.Mori, H.Kawakata, Y.Iio, H.Ogasawara
  • Journal Title: Journal of Geophysical Research 110
• [Journal Article] Multidisciplinary Monitoring of the Entire Life Span of an Earthquake in South African Gold Mines (2005)
  • Author(s): H.Ogasawara et al.
  • Journal Title: Proc. 6th Internat.Symp. Rockburst Seismicity in Mines (in press)
• [Journal Article] High-resolution Strain Monitoring During M>2 Events in a South African Deep Gold Mine in Close Proximity to Hypocentres (2005)
  • Author(s): H.Ogasawara et al.
  • Journal Title: Proc. 6th Internat.Symp. Rockburst Seismicity in Mines (in press)
• [Journal Article] 2003年の南アフリカ金鉱山の地震発生・制御・防災と予知 (2004)
  • Author(s): 小笠原宏, 他
  • Journal Title: 月刊地球 号外No.46 Pages: 68-74
• [Journal Article] M4.6地震の震源(南アフリカMathabeng金鉱山) (2004)
  • Author(s): 小笠原宏
  • Journal Title: 地質ニュース 第597号 Pages: 1-2
• [Journal Article] M2級地震の震源と応力集中(南アフリカTauTona金鉱山) (2004)
  • Author(s): 小笠原宏, 佐藤隆司
  • Journal Title: 地質ニュース 第597号 Pages: 3-4
• [Journal Article] Semi-controlled seismogenic experiments in South African deep gold mines (2002)
  • Author(s): Ogasawara, H., et al.
  • Journal Title: J.South African Inst.Mining Metallurgy Vol.102(No.4) Pages: 243-250
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] A preliminary report in continuous 24-bit 25-Hz strain monitoring on seismogenic faults of M〜3 in deep gold mines. (2002)
  • Author(s): Ogasawara, H., et al.
  • Journal Title: Proc.Internat.Workshop Phys.Active Fault, Tech.Note Nat.Res.Inst.Eaarth Sci.Disast.Prev No.234 Pages: 287-293
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Review of the Semi-Controlled Earthquake Generation Experiments in South African Deep Gold Mines (1992-2001). (2002)
  • Author(s): Ogasawara, H., et al.
  • Journal Title: In Seismogenic Process Monitoring (Ogasawara et al. eds.), Balkema, Pages: 119-150
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Microearthquake scaling retationship using near-source, redundant, wide-dynamic-range accelerograms in a South African deep gold mine. (2002)
  • Author(s): Ogasawara, H., et al.
  • Journal Title: Seismogenic Process Monitoring (Ogasawara et al. eds.), Balkema, Pages: 151-164
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Near source observation of small initial phase generated by earthquakes in a deep gold mine in South Africa (2002)
  • Author(s): Satoh, T., et al.
  • Journal Title: Seismogenic Process Monitoring (Ogasawara et al. eds.), Balkema Pages: 165-171
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Temporal variation of seismic parameters associated with an Mw〜2 event monitores at a 100〜200 m distance. (2002)
  • Author(s): Ogasawara, H., et al.
  • Journal Title: Seismogenic Process Monitoring (Ogasawara et al. eds.), Balkema, Pages: 173-184
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Location and temporal variation of shear wave splitting in a South AFrican gold mine. (2002)
  • Author(s): Nagai, N., et al.
  • Journal Title: Seismogenic Process Monitoring (Ogasawara et al. eds.), Balkema Pages: 185-198
  • Description: 「研究成果報告書概要(和文)」より
• [Journal Article] Semi-controlled seismogenic experiments in South African deep gold mines. (2002)
  • Author(s): Ogasawara, H., Sato, S., Nishii, S., Sumitomo, N., Ishii, H., Iio, Y., Nakao, S., Ando, M., Takano, M., Nagai, N., Ohkura, T., Kawakata, H., Satoh, T., Kusunose, K., Cho, A., Mendecki, A., Cichowicz, A., Green, R.W.E., Kataka, M.O.
  • Journal Title: J.South African Inst.Mining Metallurgy Vol.102 (No.4) Pages: 243-250
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] The Research group for Semi-controlled Earthquake Generation Experiment in South African Deep Gold Mines. A preliminary report on continuous 24-bit 25-Hz strain monitoring on seismogenic faults of M 3 in deep gold mines. (2002)
  • Author(s): Ogasawara, H., Ishii, H., Moriyama, S., Iio, Y.
  • Journal Title: Proc.Internat.Workshop Phys.Active Fault, Tech.Note Nat.Res.Inst.Earth Sci.isast.Prev. No.234 Pages: 287-293
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Review of the Semi-Controlled Earthquake Generation Experiments in South African Deep Gold Mines (1992-2001) (2002)
  • Author(s): Ogasawara, H., The Research Group for Semi-Controlled experiments in South African Gold mine
  • Journal Title: Seismogenic Process Monitoring (Ogasawara et al.eds.) Balkema Pages: 119-150
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Microeathquake scaling relationship using near-source, redundant, wide-dynamic-range accelerograms in a South African deep gold mine. (2002)
  • Author(s): Ogasawara, H., Miwa, T., Research Group for Earthquake Generation Experiments in South African Deep Gold Mines
  • Journal Title: Seismogenic Process Monitoring (Ogasawara et al.eds.) Balkema Pages: 151-164
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Near source observation of small initial phase generated by earthquakes in a deep gold mine in South Africa. (2002)
  • Author(s): Satoh, T., The Research Group for Semi-controlled experiments in South African Gold mine
  • Journal Title: Seismogenic Process Monitoring (Ogasawara et al.eds.) Balkema Pages: 165-171
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Temporal variation of seismic parameters associated with an Mw〜2 event monitored at a 100〜200m distance. (2002)
  • Author(s): Ogasawara, H., Sato, S., Nishii, S., Research Group for Earthquake Generation Experiments in South African Deep Gold Mines
  • Journal Title: Seismogenic Process monitoring (Ogasawara et al.eds.) Balkema Pages: 173-184
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Location and temporal variation of shear wave splitting in a South African gold mine. (2002)
  • Author(s): Nagai, N., Ando, M., Ogasawara, H., Ohkura, T., Iio, Y., Cho, A., The Research Group for Semi-controlled experiments in South African Gold mine
  • Journal Title: Seismogenic Process Monitoring (Ogasawara et al.eds.) Balkema Pages: 185-198
  • Description: 「研究成果報告書概要(欧文)」より
• [Book] Seismogenic Process Monitoring (2002)
  • Author(s): Ogasawara, H., Yanagidani T., Ando, M.(eds.)
  • Total Pages: 412
  • Publisher: Rotterdam : Balkema
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] 小笠原 宏, 飯尾能久, 中谷正生, 南アフリカ金鉱山ににおける半制御地震発生実験国際共同研究グループ: "南ア金鉱山における半制御地震発生実験(2002-2006)"月刊地球. 25・10. 815-817 (2003)
• [Publications] Ogasawara, H. et al.: "Semi-controlled seismogenic experiments in South African deep gold mines"J. South African Inst. Mining Metallurgy. 102・4. 243-250 (2002)
• [Publications] Ogasawara, H. et al.: "A preliminary report on continuous 24-bit 25-Hz strain monitoring on seismogenic faults of M〜3 in deep gold mines"Proc. Internat. Workshop Phys. Active Fault, Tech. Note Nat. Res. Inst. Earth Sci. Disast. Prey. 234. 287-293 (2002)
• [Publications] H.Ogasawara: "A key point of potential future hypocenter fault studies in deep mines : a report on a scientific tour of RaSiM5"Proc. Internat. Workshop Phys. Active Fault, Tech. Note Nat. Res. Inst. Earth Sci. Disast. Prev.. 234. 294-298 (2002)
• [Publications] Ogasawara, H. et al.: "A review of the Semi-Controlled Earthquake Generation Experiments in South African Deep Gold Mines (1992-2001)"Seismogenic Process Monitoring (Balkema). 119-150 (2002)
• [Publications] Ogasawara, H., T.Yanagidani, M.Ando (eds.): "Seismogenic Process Monitoring"Balkema. 412 (2002)