临汾市城区主要断裂活动性及地震危险性评价
发布时间：2018-09-12 16:39
【摘要】：临汾地区位于新构造活动强烈的汾渭断陷盆地中部,历史上曾发生过多次破坏性地震,是具有孕育和发生中强地震的构造条件。论文基于临汾市活断层探测工作中利用建立第四纪标准地层剖面、反射波地震勘探、钻孔联合剖面、开挖探槽及大型剖面等方法取得的大量基础数据,对研究区内主要发震断层包括罗云山山前断裂和郭家庄断裂进行精确定位及分段,尽可能掌握断裂次级段落的几何学、活动性特征,并采取适合研究区构造特点的评价方法评价其潜在的地震最大震级、地震平均复发间隔及发生概率。得到主要成果包括:(1)研究区地表出露的冲洪积物多是晚更新世至全新世地层,中更新世的湖积层较少出露。根据遥感影像、DEM影像分析及野外地质填图工作,综合绘制出研究区地貌特征图、第四纪地层分布图。由区内第四纪控制性钻孔数据加之参照前人有关研究结果综合分析,研究区内第四地层划分方案如下:全新统(Q4)0.0~0.4m,层厚0.4m;上更新统(Q3)0.4~80.8m,层厚80.4m;中更新统(Q2),80.8~245m,揭露厚度164.2m。(2)罗云山山前断裂控制临汾盆地的发育和主体构造格局,从断裂的几何结构、活动性质及时代划分,自北向南分为7段:罗云村段(F1)、万安段(F2)、亢村段(F3)、土门段(F4)、龙祠段(F5)、蔚村段(F6)及范家庄~西xY口段(F7)。(3)罗云村段(F1)表现为三个呈左阶雁列分布的次级断层,最新活动时间为晚更新世早期,垂直位移速率为0.075mm/a;万安段(F2)断裂活动强度由北东往西南逐渐变弱,最新活动时间应是晚更新世中期偏晚,垂直活动速率为0.1mm/a;亢村段(F3)T2阶地面连续,晚更新世以来活动不强;土门段(F4)最新活动发生在8ka~12ka之间,为全新世早期活动断层,平均滑动速率0.06mm/a;龙祠段(F5)自晚更新世晚期以来发生过4次地震事件:最新一次事件断错了地表下2.5m、距今3ka的垆土层,可能与公元649年7?级地震有关,全新世活动速率为0.41mm/a;蔚村段(F6)在晚更新世中、晚期发生过三次事件,活动速率为0.017mm/a;范家庄~西xY口段(F7)最新一次事件距今17ka±,活动速率在0.13mm/a~0.22mm/a之间。(4)罗云山山前断裂的右旋扭动主要发生在蔚村以北,沿断裂往南,断层右旋扭动量逐渐减小,在范家庄至西xY口段(F7)表现为是完全的正断层。(5)罗云山山前断裂距今17ka以来存在3次事件,平均间隔7ka左右,E1事件可能与公元649年地震有关,垂直位移2.9m;E2事件距今8.14ka~10ka,垂直位移2.2m~3.0m;E3事件距今16.4ka~18.48ka,垂直位移3.0~3.5m。晚更新世中、晚期以来,除罗云村段(F1)以外,断裂的活动是连续分布、整体活动的,而最新一次活动仅在龙祠段(F5)有表现,该段为整条断裂活动最强烈的部分。(6)郭家庄断裂是分割临汾凹陷甘亭和龙祠沉降中心的一条断裂,分为呈右阶展布的南、北两段,北段(北芦段)长9km,南段(郭家庄段)长16km。(7)郭家庄断裂钻探揭示范围内,可见不同层位的地层都有不同程度错断,断距随深度加深而增大,最大可达1-1.5m。断裂至少错断年龄为66.6ka的晚更新世地层,结合前人资料及野外地质调查结果,该断裂最新活动时代为全新世。(8)区域历史及现今地震时间分布具3个地震活跃期,活跃期中还存在持续10~30年、间隔为300年左右地震活动高潮时段;1970年以来现今中、小地震与M≥4.7级历史地震的空间展布都主要分布于太原盆地和临汾盆地,表明区域地震空间分布不均匀的特征;而这些地震大部分属浅源地震,主要分布于地表5-24km内。因此,区域上自1813年以来的地震活跃期尚未结束,作为区域地震主要分布区,临汾断陷盆地也是未来百年发生浅源强震活动的主要场所。(9)震源机制解与构造应力场显示,研究区内最大主应力轴(σ1)产状(237°,8°),最小主应力轴(σ3)产状(144°,21°),中间主应力轴(σ2)产状(346°,67°)。结果与华北、山西地区的构造应力场完全一致。中强以上地震的优势破裂方向为NNE和NWW,震源错动为走滑类型,地震断裂为高角度正断性质。(10)根据断裂相对危险段的判断标准,最终确定罗云山山前断裂除南端范家庄~西xY口段(F7)外,其余共90km长的部分为该断裂的相对危险段。郭家庄断裂整段共25km长的部分为相对危险段。(11)依据邓起东、龙峰总结的华北经验关系(地震强度—破裂尺度)、WC经验关系(地震强度—地表破裂长度和破裂面积)、地震强度—地震矩的经验关系,得到对应的罗云山山前断裂相对危险段潜在地震最大震级分别为7.78、7.50、7.67,再赋予其不同的权系数,综合评估罗云山山前断裂相对危险段潜在地震最大震级为Ms=7.68。郭家庄断裂相对危险段潜在地震最大震级为Ms=7.05。(12)罗云山山前断裂地震准间隔7ka,最新地震事件离逝时间为1366年,郭家庄断裂地震事件间隔为1800年,最新事件离逝时间为320年;对于泊松模型和布朗时间过程模型,综合得出罗云山山前断裂相对危险段潜在最大地震(Ms=7.68)未来50a、100a及200a的发震概率分别为0.009、0.018和0.033,郭家庄断裂相对危险段潜在最大地震(Ms=7.05)在未来50a、100a及200a的发震概率为0.033、0.066和0.128。
[Abstract]:Linfen area is located in the middle part of Fenwei fault depression basin with strong neotectonic activity.There have been many destructive earthquakes in the history,which is the tectonic condition for producing and producing moderate-strong earthquakes.Based on the exploration of active faults in Linfen city,this paper uses the establishment of Quaternary standard stratum section,reflection seismic exploration,borehole joint section,and excavation exploration. A large number of basic data obtained by trough and large section methods are used to precisely locate and segment the main seismogenic faults in the study area, including Luoyunshan piedmont fault and Guojiazhuang fault, to grasp the geometry and activity characteristics of the secondary faults as much as possible, and to evaluate the potential earthquakes by adopting evaluation methods suitable for the structural characteristics of the study area. Max magnitude, average recurrence interval and occurrence probability of earthquakes. The main results are as follows: (1) Most of the alluvial and diluvial materials exposed on the surface of the study area are from Late Pleistocene to Holocene, while the lacustrine layers of the Middle Pleistocene are less exposed. According to the Quaternary controlled borehole data and the previous research results, the Quaternary stratigraphic division scheme in the study area is as follows: Holocene (Q4) 0.0-0.4 m, layer thickness 0.4 m; Upper Pleistocene (Q3) 0.4-80.8 m, layer thickness 80.4 m; Middle Pleistocene (Q2), 80.8-245 m, exposed thickness 164.2 M. (2) Luoyunshan piedmont fault control. From north to south, the Linfen basin is divided into seven sections: Luoyuncun section (F1), Wan'an section (F2), Kangcun section (F3), Tumen section (F4), Longci section (F5), Yucun section (F6) and Fanjiazhuang-XixY section (F7). (3) Luoyuncun section (F1) is divided into three sub-sections with left echelon distribution. The latest active time of faults is early Late Pleistocene with a vertical displacement rate of 0.075 mm/a; the activity intensity of the Wan'an section (F2) faults gradually weakens from NE to SW; the latest active time should be mid-Late Pleistocene with a vertical activity rate of 0.1 mm/a; the surface of the Kangcun section (F3) T2 is continuous and the activity is not strong since Late Pleistocene; and the Tumen section (F4) is the latest. The activity occurred between 8KA and 12ka, with an average slip rate of 0.06mm/a. Four earthquakes have occurred in the Longci section (F5) since the late Late Pleistocene. The latest event has broken 2.5m beneath the surface. The loess layer 3 Ka away from the present may be related to the magnitude 7?Earthquake in 649 A.D. The Holocene activity rate is 0.41mm/a. F6) Three events occurred in the middle and late Late Pleistocene with an activity rate of 0.017 mm/a, and the latest event in the section of Fanjiazhuang-XixY (F7) was 17 Ka (+) and the activity rate was 0.13 mm/a-0.22 mm/a. (4) The dextral torsion of the Luoyunshan piedmont fault occurred mainly North of Yucun, along the fault to the south, and the dextral torsion of the fault gradually decreased. Fifth, the Luoyunshan piedmont fault has three events since 17ka, with an average interval of about 7ka. The E1 event may be related to the 649 AD earthquake, with a vertical displacement of 2.9m; the E2 event is 8.14ka~10ka, with a vertical displacement of 2.2m~3.0m; the E3 event is 16.4ka~18.48ka, with a vertical displacement of 3.0~3.5m.Late Pleistocene. Since the middle and late stages, except Luoyuncun (F1), the activity of the fault has been continuously distributed, and the latest activity has been shown only in Longci (F5), which is the most active part of the whole fault. (6) Guojiazhuang fault is a fault that separates Ganting and Longci subsidence centers in Linfen depression, and is divided into South and North with right steps. The northern section (Beilu section) is 9 km long and the southern section (Guojiazhuang section) is 16 km long. As a result, the latest active epoch of the fault is Holocene. (8) There are three active periods in the regional history and the present seismic time distribution, and the active period still lasts for 10-30 years, with an interval of about 300 years. Since 1970, the spatial distribution of small earthquakes and historical earthquakes with M (>4.7) has been mainly distributed in the Taiyuan Basin and the adjacent area. The Fen Basin shows that the spatial distribution of regional earthquakes is not uniform, and most of these earthquakes are shallow earthquakes, mainly distributed within 5-24 km of the earth's surface. Therefore, the active period of earthquakes in the region since 1813 has not yet ended. As the main distribution area of regional earthquakes, the Linfen Fault Basin is also the main field of shallow strong earthquakes in the next century. (9) The focal mechanism solution and the tectonic stress field show that the maximum principal stress axis (_1) occurrence (237 degrees, 8 degrees), the minimum principal stress axis (_3) occurrence (144 degrees, 21 degrees) and the intermediate principal stress axis (_2) occurrence (346 degrees, 67 degrees) are consistent with the tectonic stress field in North China and Shanxi. (10) According to the criterion of judging the relative dangerous section of the fault, the Luoyunshan piedmont fault is determined to be the relative dangerous section of the fault, with the exception of the southern Fanjiazhuang-XixY section (F7), and the remaining 90 km long section is the relative dangerous section of the fault. According to the empirical relationship of North China (earthquake intensity-rupture scale), WC empirical relationship (earthquake intensity-surface rupture length and rupture area), earthquake intensity-seismic moment summarized by Deng Qidong and Longfeng, the maximum magnitudes of potential earthquakes corresponding to the relative dangerous section of Luoyun Mountain piedmont fault are 7.78, 7.50, 7.67 respectively, which are given No. With the same weight coefficient, the maximum magnitude of potential earthquakes in the relatively dangerous section of Luoyunshan piedmont fault is Ms=7.68. The maximum magnitude of potential earthquakes in the relatively dangerous section of Guojiazhuang fault is Ms=7.05. (12) The quasi-interval of Luoyunshan piedmont fault earthquakes is 7 ka, the latest time of earthquake events is 1366, and the interval of Guojiazhuang fault earthquakes is 1800 years. For Poisson model and Brownian time process model, the probabilities of the potential maximum earthquakes (Ms = 7.68) in the next 50 years, 100 years and 200 years are 0.009, 0.018 and 0.033 respectively, and the potential maximum earthquakes (Ms = 7.05) in the next 50, 100 and 200 years in the relatively dangerous section of the Guojiazhuang fault. The probability of occurrence is 0.033,0.066 and 0.128..
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.2
本文编号：2239606
[Abstract]:Linfen area is located in the middle part of Fenwei fault depression basin with strong neotectonic activity.There have been many destructive earthquakes in the history,which is the tectonic condition for producing and producing moderate-strong earthquakes.Based on the exploration of active faults in Linfen city,this paper uses the establishment of Quaternary standard stratum section,reflection seismic exploration,borehole joint section,and excavation exploration. A large number of basic data obtained by trough and large section methods are used to precisely locate and segment the main seismogenic faults in the study area, including Luoyunshan piedmont fault and Guojiazhuang fault, to grasp the geometry and activity characteristics of the secondary faults as much as possible, and to evaluate the potential earthquakes by adopting evaluation methods suitable for the structural characteristics of the study area. Max magnitude, average recurrence interval and occurrence probability of earthquakes. The main results are as follows: (1) Most of the alluvial and diluvial materials exposed on the surface of the study area are from Late Pleistocene to Holocene, while the lacustrine layers of the Middle Pleistocene are less exposed. According to the Quaternary controlled borehole data and the previous research results, the Quaternary stratigraphic division scheme in the study area is as follows: Holocene (Q4) 0.0-0.4 m, layer thickness 0.4 m; Upper Pleistocene (Q3) 0.4-80.8 m, layer thickness 80.4 m; Middle Pleistocene (Q2), 80.8-245 m, exposed thickness 164.2 M. (2) Luoyunshan piedmont fault control. From north to south, the Linfen basin is divided into seven sections: Luoyuncun section (F1), Wan'an section (F2), Kangcun section (F3), Tumen section (F4), Longci section (F5), Yucun section (F6) and Fanjiazhuang-XixY section (F7). (3) Luoyuncun section (F1) is divided into three sub-sections with left echelon distribution. The latest active time of faults is early Late Pleistocene with a vertical displacement rate of 0.075 mm/a; the activity intensity of the Wan'an section (F2) faults gradually weakens from NE to SW; the latest active time should be mid-Late Pleistocene with a vertical activity rate of 0.1 mm/a; the surface of the Kangcun section (F3) T2 is continuous and the activity is not strong since Late Pleistocene; and the Tumen section (F4) is the latest. The activity occurred between 8KA and 12ka, with an average slip rate of 0.06mm/a. Four earthquakes have occurred in the Longci section (F5) since the late Late Pleistocene. The latest event has broken 2.5m beneath the surface. The loess layer 3 Ka away from the present may be related to the magnitude 7?Earthquake in 649 A.D. The Holocene activity rate is 0.41mm/a. F6) Three events occurred in the middle and late Late Pleistocene with an activity rate of 0.017 mm/a, and the latest event in the section of Fanjiazhuang-XixY (F7) was 17 Ka (+) and the activity rate was 0.13 mm/a-0.22 mm/a. (4) The dextral torsion of the Luoyunshan piedmont fault occurred mainly North of Yucun, along the fault to the south, and the dextral torsion of the fault gradually decreased. Fifth, the Luoyunshan piedmont fault has three events since 17ka, with an average interval of about 7ka. The E1 event may be related to the 649 AD earthquake, with a vertical displacement of 2.9m; the E2 event is 8.14ka~10ka, with a vertical displacement of 2.2m~3.0m; the E3 event is 16.4ka~18.48ka, with a vertical displacement of 3.0~3.5m.Late Pleistocene. Since the middle and late stages, except Luoyuncun (F1), the activity of the fault has been continuously distributed, and the latest activity has been shown only in Longci (F5), which is the most active part of the whole fault. (6) Guojiazhuang fault is a fault that separates Ganting and Longci subsidence centers in Linfen depression, and is divided into South and North with right steps. The northern section (Beilu section) is 9 km long and the southern section (Guojiazhuang section) is 16 km long. As a result, the latest active epoch of the fault is Holocene. (8) There are three active periods in the regional history and the present seismic time distribution, and the active period still lasts for 10-30 years, with an interval of about 300 years. Since 1970, the spatial distribution of small earthquakes and historical earthquakes with M (>4.7) has been mainly distributed in the Taiyuan Basin and the adjacent area. The Fen Basin shows that the spatial distribution of regional earthquakes is not uniform, and most of these earthquakes are shallow earthquakes, mainly distributed within 5-24 km of the earth's surface. Therefore, the active period of earthquakes in the region since 1813 has not yet ended. As the main distribution area of regional earthquakes, the Linfen Fault Basin is also the main field of shallow strong earthquakes in the next century. (9) The focal mechanism solution and the tectonic stress field show that the maximum principal stress axis (_1) occurrence (237 degrees, 8 degrees), the minimum principal stress axis (_3) occurrence (144 degrees, 21 degrees) and the intermediate principal stress axis (_2) occurrence (346 degrees, 67 degrees) are consistent with the tectonic stress field in North China and Shanxi. (10) According to the criterion of judging the relative dangerous section of the fault, the Luoyunshan piedmont fault is determined to be the relative dangerous section of the fault, with the exception of the southern Fanjiazhuang-XixY section (F7), and the remaining 90 km long section is the relative dangerous section of the fault. According to the empirical relationship of North China (earthquake intensity-rupture scale), WC empirical relationship (earthquake intensity-surface rupture length and rupture area), earthquake intensity-seismic moment summarized by Deng Qidong and Longfeng, the maximum magnitudes of potential earthquakes corresponding to the relative dangerous section of Luoyun Mountain piedmont fault are 7.78, 7.50, 7.67 respectively, which are given No. With the same weight coefficient, the maximum magnitude of potential earthquakes in the relatively dangerous section of Luoyunshan piedmont fault is Ms=7.68. The maximum magnitude of potential earthquakes in the relatively dangerous section of Guojiazhuang fault is Ms=7.05. (12) The quasi-interval of Luoyunshan piedmont fault earthquakes is 7 ka, the latest time of earthquake events is 1366, and the interval of Guojiazhuang fault earthquakes is 1800 years. For Poisson model and Brownian time process model, the probabilities of the potential maximum earthquakes (Ms = 7.68) in the next 50 years, 100 years and 200 years are 0.009, 0.018 and 0.033 respectively, and the potential maximum earthquakes (Ms = 7.05) in the next 50, 100 and 200 years in the relatively dangerous section of the Guojiazhuang fault. The probability of occurrence is 0.033,0.066 and 0.128..
【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P315.2
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