北京平原主要活动断裂全新世活动定量研究及未来地震危险性预测
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摘要
<正> 一、前言北京平原位于华北平原西北角,地处燕山南缘与太行山东北缘衔接地带。源自燕山山脉的潮白河及太行山山脉的永定河构成北京平原区两大水系。北京平原属于山前冲洪积平原,总体地势西北高东南低,海拔高程50～10m,坡降5‰。北京市坐落在北京冲洪积平原的后缘。北京平原的活动构造为隐伏活动构造,增加了该地区地震构造研究的难度。本文将展示近年对这一地区主要活动断裂开展调查取得的主要结果,并对该地区未来强震危险性进行探讨。
The Holocene activities of some major active faults in the Beijing Plain have been studied quantitatively in recent years. The main results are introduced in this paper. The major active faults include: 1) the NNE-trending Xiadian fault, which controls the western boundary of the Dachang depression, 2) the NW-trending Nankou-Sunhe fault, which controls the northeastern boundary of the Machikou depression, and 3) the Gaoliying fault which extends along the western side of the Huairou-Shuenyi depression. Trenching profiles across the Xiadian fault near Qixinzhuang show that there were 4 paleo-earthquake events occurred during Holocene. The 4 events were dated as in 10850～9710 a.B.P., 7390～6680 a.B.P., 5416～2233 a.B.P., and AD 1679(the Sanhe-Pinggu M=8 earthquake), respectively. The average recurrence interval of these events was about 3336±396 years. The average co-seismic vertical displacement was about 1.4 m. By analyzing the throw of faulted strata obtained from drilling data of Pangezhuang near the Xiadian fault, it is estimated that there have been 8 paleo-events during the past 30000 years. The average recurrence interval of these events were about 3947～4625 years, while the average co-seismic vertical displacement was about 1.69 m. As to the Nankou-Sunhe fault, studies on the trenching profiles near Jiuxian, Changping County revealed that there had been 3 paleo-events occurred along the fault during Holocene. The 3 events were dated, respectively, as in 12240 a.B.P., 7894～7640 a.B.P., and 3987～3670 a.B.P. The time interval between them were 3938±186 and 4673±209 years. The average coseismic vertical displacement was about 1.67 m. According to some empirical formula concerning displacement-magnitude relation established for the North China region, the relevant magnitude of the paleo-events revealed in Jiuxian trenching profiles should be about 7.8. For the Gaoliying fault, drilling data in Gaogezhuang, Huairou County revealed 2 paleo-events during Holocene, and they were dated as in 3510 a.B.P, and 7050 a.B.P., respectively. Besides, it is estimated that there have been 6 times of fault activities during the period of the past 28000 years. The average interval of these paleo-events was about 4600 years, while the average co-seismic vertical displacement was about 4.6 m. Based on the above-mentioned quantitative researches on Holocene active faults, we attempt to predict the potential strong earthquake places and their magnitude upper limits in the area concerned. By means of seismic potential probability assessment of characteristic earthquakes, we have assessed the seismic potential in the areas concerned for the coming 20, 50, and 100 years. It is obtained that, for the Gaoliying fault and the Nankou-Sunhe fault, the accumulative probabilities reached 0.54 and 0.40, respectively, for earthquakes with M=7.5～7.8 to occur in the coming 50 years; and that, for the Daxing-Tongxian fault, the accumulative probability reached 0.66 for earthquakes with M=6～6.9 to occur in the coming 50 years.
The Holocene activities of some major active faults in the Beijing Plain have been studied quantitatively in recent years. The main results are introduced in this paper. The major active faults include: 1) the NNE-trending Xiadian fault, which controls the western boundary of the Dachang depression, 2) the NW-trending Nankou-Sunhe fault, which controls the northeastern boundary of the Machikou depression, and 3) the Gaoliying fault which extends along the western side of the Huairou-Shuenyi depression. Trenching profiles across the Xiadian fault near Qixinzhuang show that there were 4 paleo-earthquake events occurred during Holocene. The 4 events were dated as in 10850～9710 a.B.P., 7390～6680 a.B.P., 5416～2233 a.B.P., and AD 1679(the Sanhe-Pinggu M=8 earthquake), respectively. The average recurrence interval of these events was about 3336±396 years. The average co-seismic vertical displacement was about 1.4 m. By analyzing the throw of faulted strata obtained from drilling data of Pangezhuang near the Xiadian fault, it is estimated that there have been 8 paleo-events during the past 30000 years. The average recurrence interval of these events were about 3947～4625 years, while the average co-seismic vertical displacement was about 1.69 m. As to the Nankou-Sunhe fault, studies on the trenching profiles near Jiuxian, Changping County revealed that there had been 3 paleo-events occurred along the fault during Holocene. The 3 events were dated, respectively, as in 12240 a.B.P., 7894～7640 a.B.P., and 3987～3670 a.B.P. The time interval between them were 3938±186 and 4673±209 years. The average coseismic vertical displacement was about 1.67 m. According to some empirical formula concerning displacement-magnitude relation established for the North China region, the relevant magnitude of the paleo-events revealed in Jiuxian trenching profiles should be about 7.8. For the Gaoliying fault, drilling data in Gaogezhuang, Huairou County revealed 2 paleo-events during Holocene, and they were dated as in 3510 a.B.P, and 7050 a.B.P., respectively. Besides, it is estimated that there have been 6 times of fault activities during the period of the past 28000 years. The average interval of these paleo-events was about 4600 years, while the average co-seismic vertical displacement was about 4.6 m. Based on the above-mentioned quantitative researches on Holocene active faults, we attempt to predict the potential strong earthquake places and their magnitude upper limits in the area concerned. By means of seismic potential probability assessment of characteristic earthquakes, we have assessed the seismic potential in the areas concerned for the coming 20, 50, and 100 years. It is obtained that, for the Gaoliying fault and the Nankou-Sunhe fault, the accumulative probabilities reached 0.54 and 0.40, respectively, for earthquakes with M=7.5～7.8 to occur in the coming 50 years; and that, for the Daxing-Tongxian fault, the accumulative probability reached 0.66 for earthquakes with M=6～6.9 to occur in the coming 50 years.
引文
① 北京平原钻孔柱状图图集,1987,北京市地震地质会战研究成果汇编(5) ,北京市地震地质会战办公室。
② 北京地震地质会战第二专题组,1979,北京地区活动构造体系图说明书。
① 焦振兴等,1983,夏垫断裂晚更新世以来活动性初探。
① 北京市地震地质会战专题成果第四专题组,1982,北京平原区全新世构造活动调查研究。
② 江娃利等,1999,首都圈平原区隐伏活动断裂定量化研究。
① 梁金鹏,1981,北京市怀柔县桃山村ME-3000激光电测距点选点报告,地震地质大队二队。
[1] 彭一民、李鼎荣等,北京平原区同生断裂的某些特征及其研究意义,地震地质,Vol.3． No.2,1981。
[2] 孟宪梁、杜春涛等,1679年三河-平谷大震的地震断裂带,地震,No3,1983。
[3] 孟宪梁、杜春涛等,1679年三河-平谷8级地震,中国特大地震研究,北京:地震出版社,1988。
[4] 向宏发、方仲景、徐杰等,三河-平谷8级地震区的构造背景与大震重复性研究,地震地质,Vol.10,No.1,1988。
[5] 向宏发、方仲景等,隐伏断裂研究及其工程应用--以北京平原区为例,北京:地震出版社,1994。
[6] 冉勇康、邓起东等,1679年三河-平谷8级地震发震断层的古地震及重复间隔,地震地质,Vol.19,No.3,1997。
[7] 徐锡伟等,用钻孔地层剖面记录恢复古地震序列,河北夏垫断裂古地震研究,地震地质,Vol.22,No.1,2000。
[8] 江娃利等,北京平原夏垫断裂齐心庄探槽古地震事件研究,地震地质,Vol.22,No.4,2000。
[9] 江娃利等,北京平原夏垫断裂潘各庄钻孔晚更新世晚期以来古地震事件分析,活动断裂研究(8) ,活动断裂研究编委会,北京:地震出版社,2000。
[10] 徐海鹏、李树德、杨景春,北京南口山前断裂活动及其对地貌发育的影响,中国地理学会第一次构造地貌学术讨论会论文选集,北京:科学出版社,1984。
[11] 邓起东、于贵华等,地震地表破裂参数与震级关系的研究,活动断裂研究(2) ,北京:地震出版社,1992。
[12] 方仲景,第四纪活动构造,高文学,马瑾主编,首都圈地震地质研究与地震灾害,北京:地震出版社,1993。
[13] 邓志辉、马瑾等,首都圈地震活动性,高文学、马瑾主编,首都圈地震地质环境与地震灾害,北京:地震出版社,1993。
[14] 汪良谋、王绳祖等,首都圈地震危险性预测研究,高文学、马瑾主编,首都圈地震地质环境与地震灾害,北京:地震出版社,1993。
[15] 闻学泽,活动断裂地震潜势的定量评估,北京:地震出版社,1995。
[16] 闻学泽、汪一鹏,我国活动断裂地震危险性研究的进展与问题,活动断裂研究(7) ,北京:地震出版社,1999。
② 北京地震地质会战第二专题组,1979,北京地区活动构造体系图说明书。
① 焦振兴等,1983,夏垫断裂晚更新世以来活动性初探。
① 北京市地震地质会战专题成果第四专题组,1982,北京平原区全新世构造活动调查研究。
② 江娃利等,1999,首都圈平原区隐伏活动断裂定量化研究。
① 梁金鹏,1981,北京市怀柔县桃山村ME-3000激光电测距点选点报告,地震地质大队二队。
[1] 彭一民、李鼎荣等,北京平原区同生断裂的某些特征及其研究意义,地震地质,Vol.3． No.2,1981。
[2] 孟宪梁、杜春涛等,1679年三河-平谷大震的地震断裂带,地震,No3,1983。
[3] 孟宪梁、杜春涛等,1679年三河-平谷8级地震,中国特大地震研究,北京:地震出版社,1988。
[4] 向宏发、方仲景、徐杰等,三河-平谷8级地震区的构造背景与大震重复性研究,地震地质,Vol.10,No.1,1988。
[5] 向宏发、方仲景等,隐伏断裂研究及其工程应用--以北京平原区为例,北京:地震出版社,1994。
[6] 冉勇康、邓起东等,1679年三河-平谷8级地震发震断层的古地震及重复间隔,地震地质,Vol.19,No.3,1997。
[7] 徐锡伟等,用钻孔地层剖面记录恢复古地震序列,河北夏垫断裂古地震研究,地震地质,Vol.22,No.1,2000。
[8] 江娃利等,北京平原夏垫断裂齐心庄探槽古地震事件研究,地震地质,Vol.22,No.4,2000。
[9] 江娃利等,北京平原夏垫断裂潘各庄钻孔晚更新世晚期以来古地震事件分析,活动断裂研究(8) ,活动断裂研究编委会,北京:地震出版社,2000。
[10] 徐海鹏、李树德、杨景春,北京南口山前断裂活动及其对地貌发育的影响,中国地理学会第一次构造地貌学术讨论会论文选集,北京:科学出版社,1984。
[11] 邓起东、于贵华等,地震地表破裂参数与震级关系的研究,活动断裂研究(2) ,北京:地震出版社,1992。
[12] 方仲景,第四纪活动构造,高文学,马瑾主编,首都圈地震地质研究与地震灾害,北京:地震出版社,1993。
[13] 邓志辉、马瑾等,首都圈地震活动性,高文学、马瑾主编,首都圈地震地质环境与地震灾害,北京:地震出版社,1993。
[14] 汪良谋、王绳祖等,首都圈地震危险性预测研究,高文学、马瑾主编,首都圈地震地质环境与地震灾害,北京:地震出版社,1993。
[15] 闻学泽,活动断裂地震潜势的定量评估,北京:地震出版社,1995。
[16] 闻学泽、汪一鹏,我国活动断裂地震危险性研究的进展与问题,活动断裂研究(7) ,北京:地震出版社,1999。
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