臨汾市城區(qū)主要斷裂活動性及地震危險性評價
發(fā)布時間：2018-09-12 16:39
【摘要】：臨汾地區(qū)位于新構造活動強烈的汾渭斷陷盆地中部,歷史上曾發(fā)生過多次破壞性地震,是具有孕育和發(fā)生中強地震的構造條件。論文基于臨汾市活斷層探測工作中利用建立第四紀標準地層剖面、反射波地震勘探、鉆孔聯(lián)合剖面、開挖探槽及大型剖面等方法取得的大量基礎數(shù)據(jù),對研究區(qū)內(nèi)主要發(fā)震斷層包括羅云山山前斷裂和郭家莊斷裂進行精確定位及分段,盡可能掌握斷裂次級段落的幾何學、活動性特征,并采取適合研究區(qū)構造特點的評價方法評價其潛在的地震最大震級、地震平均復發(fā)間隔及發(fā)生概率。得到主要成果包括:(1)研究區(qū)地表出露的沖洪積物多是晚更新世至全新世地層,中更新世的湖積層較少出露。根據(jù)遙感影像、DEM影像分析及野外地質(zhì)填圖工作,綜合繪制出研究區(qū)地貌特征圖、第四紀地層分布圖。由區(qū)內(nèi)第四紀控制性鉆孔數(shù)據(jù)加之參照前人有關研究結果綜合分析,研究區(qū)內(nèi)第四地層劃分方案如下:全新統(tǒng)(Q4)0.0~0.4m,層厚0.4m;上更新統(tǒng)(Q3)0.4~80.8m,層厚80.4m;中更新統(tǒng)(Q2),80.8~245m,揭露厚度164.2m。(2)羅云山山前斷裂控制臨汾盆地的發(fā)育和主體構造格局,從斷裂的幾何結構、活動性質(zhì)及時代劃分,自北向南分為7段:羅云村段(F1)、萬安段(F2)、亢村段(F3)、土門段(F4)、龍祠段(F5)、蔚村段(F6)及范家莊~西xY口段(F7)。(3)羅云村段(F1)表現(xiàn)為三個呈左階雁列分布的次級斷層,最新活動時間為晚更新世早期,垂直位移速率為0.075mm/a;萬安段(F2)斷裂活動強度由北東往西南逐漸變?nèi)?最新活動時間應是晚更新世中期偏晚,垂直活動速率為0.1mm/a;亢村段(F3)T2階地面連續(xù),晚更新世以來活動不強;土門段(F4)最新活動發(fā)生在8ka~12ka之間,為全新世早期活動斷層,平均滑動速率0.06mm/a;龍祠段(F5)自晚更新世晚期以來發(fā)生過4次地震事件:最新一次事件斷錯了地表下2.5m、距今3ka的壚土層,可能與公元649年7?級地震有關,全新世活動速率為0.41mm/a;蔚村段(F6)在晚更新世中、晚期發(fā)生過三次事件,活動速率為0.017mm/a;范家莊~西xY口段(F7)最新一次事件距今17ka±,活動速率在0.13mm/a~0.22mm/a之間。(4)羅云山山前斷裂的右旋扭動主要發(fā)生在蔚村以北,沿斷裂往南,斷層右旋扭動量逐漸減小,在范家莊至西xY口段(F7)表現(xiàn)為是完全的正斷層。(5)羅云山山前斷裂距今17ka以來存在3次事件,平均間隔7ka左右,E1事件可能與公元649年地震有關,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、晚期以來,除羅云村段(F1)以外,斷裂的活動是連續(xù)分布、整體活動的,而最新一次活動僅在龍祠段(F5)有表現(xiàn),該段為整條斷裂活動最強烈的部分。(6)郭家莊斷裂是分割臨汾凹陷甘亭和龍祠沉降中心的一條斷裂,分為呈右階展布的南、北兩段,北段(北蘆段)長9km,南段(郭家莊段)長16km。(7)郭家莊斷裂鉆探揭示范圍內(nèi),可見不同層位的地層都有不同程度錯斷,斷距隨深度加深而增大,最大可達1-1.5m。斷裂至少錯斷年齡為66.6ka的晚更新世地層,結合前人資料及野外地質(zhì)調(diào)查結果,該斷裂最新活動時代為全新世。(8)區(qū)域歷史及現(xiàn)今地震時間分布具3個地震活躍期,活躍期中還存在持續(xù)10~30年、間隔為300年左右地震活動高潮時段;1970年以來現(xiàn)今中、小地震與M≥4.7級歷史地震的空間展布都主要分布于太原盆地和臨汾盆地,表明區(qū)域地震空間分布不均勻的特征;而這些地震大部分屬淺源地震,主要分布于地表5-24km內(nèi)。因此,區(qū)域上自1813年以來的地震活躍期尚未結束,作為區(qū)域地震主要分布區(qū),臨汾斷陷盆地也是未來百年發(fā)生淺源強震活動的主要場所。(9)震源機制解與構造應力場顯示,研究區(qū)內(nèi)最大主應力軸(σ1)產(chǎn)狀(237°,8°),最小主應力軸(σ3)產(chǎn)狀(144°,21°),中間主應力軸(σ2)產(chǎn)狀(346°,67°)。結果與華北、山西地區(qū)的構造應力場完全一致。中強以上地震的優(yōu)勢破裂方向為NNE和NWW,震源錯動為走滑類型,地震斷裂為高角度正斷性質(zhì)。(10)根據(jù)斷裂相對危險段的判斷標準,最終確定羅云山山前斷裂除南端范家莊~西xY口段(F7)外,其余共90km長的部分為該斷裂的相對危險段。郭家莊斷裂整段共25km長的部分為相對危險段。(11)依據(jù)鄧起東、龍峰總結的華北經(jīng)驗關系(地震強度—破裂尺度)、WC經(jīng)驗關系(地震強度—地表破裂長度和破裂面積)、地震強度—地震矩的經(jīng)驗關系,得到對應的羅云山山前斷裂相對危險段潛在地震最大震級分別為7.78、7.50、7.67,再賦予其不同的權系數(shù),綜合評估羅云山山前斷裂相對危險段潛在地震最大震級為Ms=7.68。郭家莊斷裂相對危險段潛在地震最大震級為Ms=7.05。(12)羅云山山前斷裂地震準間隔7ka,最新地震事件離逝時間為1366年,郭家莊斷裂地震事件間隔為1800年,最新事件離逝時間為320年;對于泊松模型和布朗時間過程模型,綜合得出羅云山山前斷裂相對危險段潛在最大地震(Ms=7.68)未來50a、100a及200a的發(fā)震概率分別為0.009、0.018和0.033,郭家莊斷裂相對危險段潛在最大地震(Ms=7.05)在未來50a、100a及200a的發(fā)震概率為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..
【學位授予單位】：成都理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P315.2
本文編號：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..
【學位授予單位】：成都理工大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：P315.2
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