慢地震慢前兆的机制研究
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摘要
通过岩石高温高压破裂实验与有机玻璃破裂试验的应力-应变曲线对比、地震波形记录(观测资料)与试样破裂波形(实验资料)对比、地震前后定点应变与主破裂前后应变形态变化的对比,认为慢地震是临界或亚临界破裂或预先滑动所致,是低频应变波动。它是材料屈服、弱化或塑性变化的必然结果。而慢前兆则是临近大地震(大破裂)前出现的诸如形变、低频地震波(破裂弹性波)等的短期及临震前兆现象,它比较可靠。但由于许多岩石主破裂前并无明显的临界破裂或预滑动现象,也并非所有岩石都一定出现明显屈服,所以也并非每个地震前都有慢地震,因此,也就不一定都出现低频波动。从而,也并不一定都出现相同的短期、临震前兆现象。
By comparing the stress-strain curves of rock samples at high temperature and high pressure with ones of plexiglas at usual temperature and axial compression, and contrasting seismic wave with ones recorded when fracture occurs in the sample , and balancing the fixed-point strain of pre- and post-earthquake with the variation of strain field pre- and main-fracture of rock sample, we understand that slow earthquake results from critical or sub-critical fracture, or pre-slid, and it is a strain wave with low frequency. It is an inevitable result due to material yield, weakening or plastic variation. The slow precursor is a sort of credible, short-term and impending precursors, such as deformation, strains wave with low frequency before the large earthquake (large fracture). Since the obvious critical-or sub-critical fracture, pre-slid or obvious yield was not observed before the fracture in all rocks, therefore, there won't be slow earthquake and the wave with low frequency before all strong earthquakes. As a result, the same short-term and impending precursor is not observed before all strong earthquakes.
By comparing the stress-strain curves of rock samples at high temperature and high pressure with ones of plexiglas at usual temperature and axial compression, and contrasting seismic wave with ones recorded when fracture occurs in the sample , and balancing the fixed-point strain of pre- and post-earthquake with the variation of strain field pre- and main-fracture of rock sample, we understand that slow earthquake results from critical or sub-critical fracture, or pre-slid, and it is a strain wave with low frequency. It is an inevitable result due to material yield, weakening or plastic variation. The slow precursor is a sort of credible, short-term and impending precursors, such as deformation, strains wave with low frequency before the large earthquake (large fracture). Since the obvious critical-or sub-critical fracture, pre-slid or obvious yield was not observed before the fracture in all rocks, therefore, there won't be slow earthquake and the wave with low frequency before all strong earthquakes. As a result, the same short-term and impending precursor is not observed before all strong earthquakes.
引文
① 高福旺,慢地震与未来地震关系的研究,1999。
[1] Linde A T, Gladwin M T, Jonhmston M J S, et al. A slow earthquake sequence on the San Andress fault[J]. Nature, 1996, 888: 65-68．
[2] Kanamori J, Cipar J J. Focal process of the great Chilen earthquake May 22, 1960[J]. Phys Earth and Planet Inter, 1974, 9: 128-136．
[3] 冯德益,潘琴龙,郑斯华,等.长周期形变波及其所反应的短期和临震地震前兆[J].地震学报,1984,6(1) :41-56．
[4] Dziewonski A M, Gilbert F. Temporal variation of the seismic moment tensor and the evidence of precursive compression for two deep earthquakes[J]. Nature, 1974, 247, 185-188．
[5] Cifuentes I L, Silver P G. Low-frequency source characteristics of the great 1960 Chilean Earthquake [J]. J Geophys Res, 1989, 94(B1) : 643-663．
[6] Ihmle P F, Jordan T H. Teleseismic search for slow precursors to large earthquake [J]. Science,1994, 266, 1547-1551．
[7] Ihmle P F, Harabaglia P, Jordan T H. Teleseismic detection of slow precursors the great 1989 Macquarie Ridge earthquake[J]. Science, 1994, 261: 177-183．
[8] Kanamori H, Haukxxon E. A slow earthquake in the santa maria basin,califormia[J]. Bull Seismol Soc Am, 1992, 82: 2087-2096．
[9] McGuire J J, Jordan T H. Further evidence for the compound mature of slow earthquake: The Prince Edward Island earthquakee of April 28, 1997[J]. J Geophys Res, 2000, 105 (B4) : 7819-2022．
[10] McGuire J J, Ihmle P F, Jordan T H. Time-domain observations of a slow precursor to the 1994 Roman the transforrn earthquake[J]. Science, 1996, 273: 82-85．
[11] Ohnaka M, Mogi K. Frequency characteristics of acoustic emission in rocks under uniaxial compression and its relation to the fracturing process to failure[J]. J Geophys Res, 1982, 87 (B5) : 3873-3884．
[12] 许昭永,杨润海,王彬,等.应变扰动--一种新的破裂前兆的试验研究[J].地震学报,1998,20(6) :628-634．
[13] Xu Z, Yang R, Zhao J, et al. Experimental study of seismic short-imminent precursory mechanism by new methods and technique[A]. the 2~(nd) APEC Cooperation for Earthquake Simulation Workshop,Tokyo, Japan, Oct. 15-21/2000, 2~(nd) ACES Workshop Proceedings[C]. edited by M. Matuura, K.Nakajima and P. Mora, 103-108．
[14] 周永胜,张流,蒋海昆,等.不同温压条件下居庸关花岗岩变形破坏与失稳形式的实验研究[J].中国地震,2002,18(4) :389-400．
[15] 片尾浩,饭尾能久(京都大学防灾研究所,地震予知研究).兵库县南部地震前震波形特异性[A].地震予知联络会文集[C].1995,620-623．
[16] Xu Z, Yang R, Zhao J, et al. Experimental Study of the Process Zone, Nucleation Zone and Plastic Area of Earthquakes by the Shadow Optical Method of Caustics[J]. PAGEOPH, 2002, 159 (9) :1951-1966．
[17] 许昭永,杨润海,赵晋明,等.加载破裂和卸载破裂的焦散阴影区动态特征的实验研究[J].地震学报,2002,24(2) :186-195．
[18] 高福旺,刘北顺.首都圈体应变变化特征与6级地震的关系[J].中国地震,1999,15(4) :370-376．
[19] 车兆宏,刘天海,尹荣珍.大同-阳高地震形变前兆演变过程[A].国家地震局科技监测司.地震形变前兆特征的识别与研究[C].北京:地震出版社,1994． 75-84．
[1] Linde A T, Gladwin M T, Jonhmston M J S, et al. A slow earthquake sequence on the San Andress fault[J]. Nature, 1996, 888: 65-68．
[2] Kanamori J, Cipar J J. Focal process of the great Chilen earthquake May 22, 1960[J]. Phys Earth and Planet Inter, 1974, 9: 128-136．
[3] 冯德益,潘琴龙,郑斯华,等.长周期形变波及其所反应的短期和临震地震前兆[J].地震学报,1984,6(1) :41-56．
[4] Dziewonski A M, Gilbert F. Temporal variation of the seismic moment tensor and the evidence of precursive compression for two deep earthquakes[J]. Nature, 1974, 247, 185-188．
[5] Cifuentes I L, Silver P G. Low-frequency source characteristics of the great 1960 Chilean Earthquake [J]. J Geophys Res, 1989, 94(B1) : 643-663．
[6] Ihmle P F, Jordan T H. Teleseismic search for slow precursors to large earthquake [J]. Science,1994, 266, 1547-1551．
[7] Ihmle P F, Harabaglia P, Jordan T H. Teleseismic detection of slow precursors the great 1989 Macquarie Ridge earthquake[J]. Science, 1994, 261: 177-183．
[8] Kanamori H, Haukxxon E. A slow earthquake in the santa maria basin,califormia[J]. Bull Seismol Soc Am, 1992, 82: 2087-2096．
[9] McGuire J J, Jordan T H. Further evidence for the compound mature of slow earthquake: The Prince Edward Island earthquakee of April 28, 1997[J]. J Geophys Res, 2000, 105 (B4) : 7819-2022．
[10] McGuire J J, Ihmle P F, Jordan T H. Time-domain observations of a slow precursor to the 1994 Roman the transforrn earthquake[J]. Science, 1996, 273: 82-85．
[11] Ohnaka M, Mogi K. Frequency characteristics of acoustic emission in rocks under uniaxial compression and its relation to the fracturing process to failure[J]. J Geophys Res, 1982, 87 (B5) : 3873-3884．
[12] 许昭永,杨润海,王彬,等.应变扰动--一种新的破裂前兆的试验研究[J].地震学报,1998,20(6) :628-634．
[13] Xu Z, Yang R, Zhao J, et al. Experimental study of seismic short-imminent precursory mechanism by new methods and technique[A]. the 2~(nd) APEC Cooperation for Earthquake Simulation Workshop,Tokyo, Japan, Oct. 15-21/2000, 2~(nd) ACES Workshop Proceedings[C]. edited by M. Matuura, K.Nakajima and P. Mora, 103-108．
[14] 周永胜,张流,蒋海昆,等.不同温压条件下居庸关花岗岩变形破坏与失稳形式的实验研究[J].中国地震,2002,18(4) :389-400．
[15] 片尾浩,饭尾能久(京都大学防灾研究所,地震予知研究).兵库县南部地震前震波形特异性[A].地震予知联络会文集[C].1995,620-623．
[16] Xu Z, Yang R, Zhao J, et al. Experimental Study of the Process Zone, Nucleation Zone and Plastic Area of Earthquakes by the Shadow Optical Method of Caustics[J]. PAGEOPH, 2002, 159 (9) :1951-1966．
[17] 许昭永,杨润海,赵晋明,等.加载破裂和卸载破裂的焦散阴影区动态特征的实验研究[J].地震学报,2002,24(2) :186-195．
[18] 高福旺,刘北顺.首都圈体应变变化特征与6级地震的关系[J].中国地震,1999,15(4) :370-376．
[19] 车兆宏,刘天海,尹荣珍.大同-阳高地震形变前兆演变过程[A].国家地震局科技监测司.地震形变前兆特征的识别与研究[C].北京:地震出版社,1994． 75-84．
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