The strain energy accumulating-releasing period and strong earthquake prediction in Sichuan-Yunnan rhombic block
-
摘要: 将川滇菱形地块分为两个地块， 分别以形变确定应变速率、 深部速度构造确定弹性模量、 联合地块体积确定地块应变能积累与时间的关系， 结合历史强震研究应变能积累释放周期以及该周期内的强震活动， 进而研究应变能积累释放与强震活动的关系. 结果表明， 地块应变能积累释放存在周期性并可预测强震震级. 在应变能积累前期， 没有强震(M≥7.0)发生； 随着时间增加， 应变能继续增加， 地块上先后发生几次强震， 但每次强震震级均小于预测震级， 即一次强震只释放了一部分能量； 而后应变能积累继续增加， 直到一、 二次特大强震(M≥7.5)发生， 将绝大部分应变能释放. 至此， 老的周期结束， 新的周期开始. 应变能积累从小到大直到最后完全释放的周期性导致了地震的平静活跃周期， 地震活跃期比平静期长得多. 本文认为， 大区域地理范围因其含有多个地块， 不宜讨论其地震平静活跃周期， 而对于小范围单次强震也不宜讨论其复发周期. 虽然活跃期中的强震从时间上看并无任何规律， 但利用活动地块应变能的积累释放曲线所预测的震级与实际震级很接近. 本文结果对于地震安全性评价工作可能有重要意义.Abstract: In this paper, the Sichuan-Yunnan rhombic block is divided into two parts. The strain rate is achieved by deformation, the elastic modulus is acquired by velocity structure in the deep, the volume of the block is calculated by the area and thickness of block, and then the variation of accumulated strain energy with time is confirmed. On this basis, combined with the research of historical strong earthquakes, the relationship between the period of energy accumulating-releasing and the seismic activity is obtained. The results show that the strain energy accumulating-releasing emerges periodically, which can be used for strong earthquake prediction. The strong earthquakes (M≥7.0) do not occur at initial stage of strain energy accumulation. The strain energy increases continuously with time and then several strong events occur firstly, but each event is smaller in magnitude than the predicted ones, i.e., one event releases a small part energy and later energy increases incessantly. The energy is not completely released until one or two great strong events (M≥7.5) occur. Thus, the old cycle ends and a new cycle starts. Obviously, the quiet to active periods are caused by the cycle of strain energy accumulation from small to great, and then to completely releasing. Active stage is much longer than the quiet one. Therefore, it is unsuitable to discuss the quiet-active period for a great geographic area covered by many blocks or to discuss the repeat period of single strong earthquake for a small region. Although the occurrence of strong earthquakes does not obey any law in time, the magnitude predicted by the strain energy accumulating-releasing curves is coincident with the real one, which may be significant for seismic safety evaluation.
-
-
![]()
图 1 川滇菱形地块地质构造图及1700年以来M≥6.7强震分布图(引自皇甫岗等，2010)
Figure 1. Geological sructure of Sichuan-Yunnan rhombic block and distribution of strong earthquakes (M≥6.7) since the year 1700 (after Huangfu et al, 2010)
![]()
图 3 川滇菱形地块东南地块(a)和西北地块(b)应变能积累释放周期及强震活动曲线， 图中纵坐标为对实际积累的应变能取对数的结果
Figure 3. The period of strain energy accumulating-releasing and seismicity curves in southeastern (a) and northwestern (b) Sichuan-Yunnan rhombic block， where the ordinate represents the result by taking logarithm of actual accumulated strain energy
表 1 川滇菱形地块东南地块强震震级(M≥7.0)与用应变能积累释放曲线所预测震级的比较
Table 1 Comparison of the magnitudes of strong earthquakes (M≥7.0) with those predicted by strain energy accumulating-releasing curve in southeastern Sichuan-Yunnan rhombic block
周期 年份 震级 北纬/° 东经/° 发震地点 能级 预测震级 第一周期 1733 7 ¾ 27.7 102.4 云南东川紫牛坡 1789 7 24.2 102.9 云南华宁路居 16.792 7.445 1799 7 23.8 102.4 云南石屏宝秀 16.862 7.492 1833 8 25.0 103.0 云南嵩明—杨林 17.233 7.739 第二周期 1850 7 ½ 27.7 102.4 四川西昌—普格 1887 7 23.7 102.5 云南石屏 16.432 7.205 1913 7 24.2 102.5 云南峨山 16.814 7.460 1925 7 25.7 100.4 云南大理 16.927 7.535 1970 7.8 24.2 102.7 云南通海 17.388 7.843 注： 能级为对实际积累的应变能取对数的结果， 下同． 
下载: 导出CSV
表 2 川滇菱形地块西北地块强震震级(M≥7.0)与用应变能积累释放曲线所预测震级的比较
Table 2 Comparison of the magnitudes of strong earthquakes (M≥7.0) with those predicted by strain energy accumulating-releasing curve in northwestern Sichuan-Yunnan rhombic block
年份 震级 北纬/° 东经/° 发震地点 能级 预测震级 1816 7 ½ 31.4 100.7 四川炉霍 1870 7 1/4 30.0 99.1 四川巴塘 16.672 7.365 1893 7 30.6 101.5 四川道孚乾宁 16.805 7.454 1896 7 32.5 98.0 四川石渠洛须 16.765 7.427 1904 7 31.0 101.1 四川道孚 16.823 7.466 1923 7 1/4 31.5 101.0 四川炉霍—道孚 17.053 7.619 1948 7 1/4 29.5 100.5 四川理塘 17.249 7.750 1955 7.5 30.0 100.4 四川康定—折多塘 17.247 7.748 1973 7.6 31.3 100.7 四川炉霍 17.273 7.766 注： 1816年四川炉霍M7 ½ 地震至1973年四川炉霍MS7.6地震为应变能积累释放的一个周期.
下载: 导出CSV
-
许绍燮. 1982. 地震活动性图象述评[C]//大陆地震活动和地震预报国际学术讨论会论文集. 北京: 地震出版社: 3-29. Xu S X. 1982. A review of the seismicity patterns[C]//A Collection of Papers of International Symposium on Continental Seismicity and Earthquake Prediction (ISCSEP). Beijing: Seismological Press: 3-29 (in Chinese).
尹祥础. 2011. 固体力学[M]. 北京: 地震出版社: 58-65, 388-427. Yin X C. 2011. Solid Mechanics[M]. Beijing: Seismological Press: 58-65, 388-427 (in Chinese).
Kanamori H. 2001. Energy budget of earthquakes and seismic efficiency[C]//Earthquake Thermodynamics and Phase Transformations in the Earth's Interior, International Geophysics Series, Volume 76. San Diego, California: Academic Press: 293-305.
Scholz C H. 1996. The Mechanics of Earthquakes and Faulting[M]. 2nd ed. New York: Cambridge University Press: 1-504.
计量
- 文章访问数: 588
- HTML全文浏览量: 240
- PDF下载量: 26
