1679年三河-平谷8级地震破裂带的大地切片实验研究
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摘要
大地切片调查法,就是在不搅动的状态下从地下切出未固结的第四纪浅部地层的垂直断片,它是一种较新的活动断层探测技术。发生在1679年9月2日的三河-平谷8级地震(烈度Ⅺ),是北京及附近地区历史上记录到的最大地震。在该地震的宏观震中——潘各庄附近,运用大地切片调查法对该地震破裂带进行了实验性探测,获得了较好的效果。实验研究表明:大地切片保留了完好的沉积细结构特征;大地切片调查实施时,要选择合适的动力源,对于北京平原这种黏土含量较高的沉积层,挖掘机加振动锤的动力组合优于吊车加振动锤的动力组合;大地切片由于振动会造成一定地层厚度的压缩,但黏土含量较高的北京地区,压缩比例基本<5%。另外,结合探槽和大地切片的对比分析,揭示了最近2次古地震事件,分别是1679年事件和该地震之前的一次事件,两次地震的垂直同震位移分别是1·4m和1·2m。
Geo-slicer method,a newly developed technique for detecting active fault,is designed to take a slice of unconsolidated Quaternary strata whose texture and structure are not destroyed. The Sanhe-Pinggu M8 earthquake of 1679 is the biggest one recorded in Beijing area. The macroscopical epicenter is located around Pangezhuang Village,Xiadian Town,Hebei Province. We successfully applied the geo-slicer method to detecting the rupture of this earthquake near its epicenter. Through our test research,we gained the following knowledge: 1)the detailed deposit structure of the unconsolidated strata can be kept in the geo-slicer; 2)the power unit should be selected to fit to different site conditions,and for Beijing area,a power unit with "grab+vibrant hammer" is better than that with "crane+hammer" ; 3)there is some shortening due to the vibration of the power,but the shortening is generally less than 5%. Moreover,synthesizing the information from the geo-slicers and trench,we found two earthquake events. One is the 1679 earthquake and the other is the one before the 1679. The vertical seismic displacements are 1.4m and 1.2m,respectively.
Geo-slicer method,a newly developed technique for detecting active fault,is designed to take a slice of unconsolidated Quaternary strata whose texture and structure are not destroyed. The Sanhe-Pinggu M8 earthquake of 1679 is the biggest one recorded in Beijing area. The macroscopical epicenter is located around Pangezhuang Village,Xiadian Town,Hebei Province. We successfully applied the geo-slicer method to detecting the rupture of this earthquake near its epicenter. Through our test research,we gained the following knowledge: 1)the detailed deposit structure of the unconsolidated strata can be kept in the geo-slicer; 2)the power unit should be selected to fit to different site conditions,and for Beijing area,a power unit with "grab+vibrant hammer" is better than that with "crane+hammer" ; 3)there is some shortening due to the vibration of the power,but the shortening is generally less than 5%. Moreover,synthesizing the information from the geo-slicers and trench,we found two earthquake events. One is the 1679 earthquake and the other is the one before the 1679. The vertical seismic displacements are 1.4m and 1.2m,respectively.
引文
何宏林,佃荣吉,下川浩一,等.2003.大地切片:一种新的活动断层探测技术[J].地震地质,25(3):438—449.HE Hong-lin,Eikichi TSUKUD,Kouichi SHIMOKAWA,et al.2003.Geo-Slicer:Anewtechnique for detecting activefault[J].Seismology and Geology,25(3):438—449(in Chinese).
盂宪梁,杜春涛,王瑞,等.l983.1679年三河-平谷大震的地震断裂带[J].地震,(3):18—23.MENG Xian-liang,DU Chun-tao,WANG Rui,et al.1983.Rupture of the Sanhe-Pinggu earthquake of1679[J].Earthquake,(3):18—23(in Chinese).
向宏发,方仲景,徐杰,等.1988.三河-平谷8级地震区的构造背景与大震重复性研究[J].地震地质,10(1):15—28.XIANG Hong-fa,FANG Zhong-jing,XU Jie,et al.1988.Study on the seismo-tectonics and earthquake recurrence ofthe Sanhe-PingguM8earthquake[J].Seismology and Geology,10(1):15—28(in Chinese).
冉勇康,邓起东,杨晓平,等.1997·1679年三河-平谷8级地震发震断层的古地震及重复间隔[J].地震地质,19(3):193—201.RAN Yong-kang,DENG Qi-dong,YANG Xiao-ping.1997.Paleoearthquakes and recurrence interval on the seismogenicfault of1679Sanhe-PingguM8earthquake,Hebei and Beijing[J].Seismology and Geology,19(3):193—201(in Chinese).
原口强,岛崎邦彦,小岛圭二,他.1998.地層?き取り装置による軟弱地盤における定方位連続地層取方法[J].地盘工学会誌,46(2):24—26.Haraguchi T,Shimazaki K,Kojima K,et al.1998.A new sampling method of unconsolidated sediments by long Geo-slicer[J].Journal of Geotechnical Engineering,46(2):24—26(in Japanese).
中田高,岛崎邦彦.1997.活断層研究のための地層?き取り装置(Geo-slicer)[J].地学雜誌,106:59—69.Nakata T,Shimazaki K.1997.Geo-slicer,a newly invented soil sampler,for high-resolution active fault studies[J].Journal of Geography,106:59—69(in Japanese).
盂宪梁,杜春涛,王瑞,等.l983.1679年三河-平谷大震的地震断裂带[J].地震,(3):18—23.MENG Xian-liang,DU Chun-tao,WANG Rui,et al.1983.Rupture of the Sanhe-Pinggu earthquake of1679[J].Earthquake,(3):18—23(in Chinese).
向宏发,方仲景,徐杰,等.1988.三河-平谷8级地震区的构造背景与大震重复性研究[J].地震地质,10(1):15—28.XIANG Hong-fa,FANG Zhong-jing,XU Jie,et al.1988.Study on the seismo-tectonics and earthquake recurrence ofthe Sanhe-PingguM8earthquake[J].Seismology and Geology,10(1):15—28(in Chinese).
冉勇康,邓起东,杨晓平,等.1997·1679年三河-平谷8级地震发震断层的古地震及重复间隔[J].地震地质,19(3):193—201.RAN Yong-kang,DENG Qi-dong,YANG Xiao-ping.1997.Paleoearthquakes and recurrence interval on the seismogenicfault of1679Sanhe-PingguM8earthquake,Hebei and Beijing[J].Seismology and Geology,19(3):193—201(in Chinese).
原口强,岛崎邦彦,小岛圭二,他.1998.地層?き取り装置による軟弱地盤における定方位連続地層取方法[J].地盘工学会誌,46(2):24—26.Haraguchi T,Shimazaki K,Kojima K,et al.1998.A new sampling method of unconsolidated sediments by long Geo-slicer[J].Journal of Geotechnical Engineering,46(2):24—26(in Japanese).
中田高,岛崎邦彦.1997.活断層研究のための地層?き取り装置(Geo-slicer)[J].地学雜誌,106:59—69.Nakata T,Shimazaki K.1997.Geo-slicer,a newly invented soil sampler,for high-resolution active fault studies[J].Journal of Geography,106:59—69(in Japanese).
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