APPLICATION AND PROGRESS OF GROUND PENETRATING RADAR IN ACTIVE FAULT DETECTION
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摘要: 结合国内外最新研究成果,对地质雷达技术在活动断裂探测中的应用进行了系统分析和总结,重点对地质雷达在城市活断层探测、古地震探测和断层识别方法的研究现状进行了阐述,并结合理塘活动断裂的应用实例进行评述。最后,提出了地质雷达探测活动断裂现存的问题,对该技术探测活动断裂的发展方向和应用前景进行了展望。Abstract: Combining with the recent research at home and abroad, the application of Ground Penetrating Radar in active fault detection was summed up and concluded. Three aspects on the application of GPR in active fault detection were put forward and reviewed:the application of GPR in urban active fault, the application of GPR in paleoearthquake and the interpretation of fault in the GPR profile, and an example of the method was illustrated to demonstrate the effectiveness of GPR method in Litang active. Finally, the existing problems of the application of GPR in active fault detection was put forward, and the direction of development and the prospect of this technology were also denoted.
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Key words:
- Ground Penetrating Radar /
- active fault /
- urban active fault /
- paleoearthquake /
- data interpretation
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0. 引言
在特定应力作用下, 活动的盐体可以克服上覆阻力向上拱起或插入上覆岩层, 从而使得上覆地层严重变形形成褶皱或断层[1~6]。盐上断层对于油气运移、油气藏形成以及金属矿床的勘探都具有重要的意义。
通过地震、井下资料分析, 露头观测, 物理实验模拟以及数值模拟等手段, 人们对于盐上断层得出一些普遍认识:盐上断层多为平直型或铲式正断层, 倾向指向盐构造中心, 从侧缘到构造中心断层近于平行或逐渐变陡, 可延伸至盐体中。但是这种认识多为经验式的定性化描述, 对于其形成原因、定量表征及断层模式总结方面研究较少。宋随宏等[7]从岩体断裂微观机制(抛物线型莫尔包络线准则)出发, 通过理论分析、数学推倒和简单的数值模拟, 初步得出了上拱力(地层受到的向上的力, 其形成机制多样, 如盐拱构造)与宏观断层形态间的定量关系。但该理论缺乏较为严格的实际论证和应用, 本文力图在该理论基础上, 以不同形态盐拱构造为对象, 数值模拟多种上拱力背景下所产生的断层形态及分布模式, 并通过与实际盐上断层相对比来证实该理论及数模结果的正确性。对于通过断层模式识别出不同盐体类型和定量表征上拱力分布规律, 精确预测未发现断层形态和分布位置等具有重要意义。
1. 断层与上拱力定量关系的研究
在上拱力背景下, 如盐拱构造, 断层的形成是地下一般应力、区域应力和上拱构造形成的应力共同作用的结果。上覆地层在上拱构造的作用下, 受到向上的上拱力和由于地层拱起拉升而形成的顺层方向的附加水平拉力共同作用。从微观角度来看, 在所有应力共同作用下, 当岩层某点处所受的正应力和剪应力达到一定关系, 该点处岩体发生断裂, 形成微裂缝。当这些微裂缝连在一起时, 即表现为宏观上的断层面。关于这种岩层断裂时的微观应力准则, 目前与实际吻合比较好的有抛物线型莫尔包络线准则。
1.1 抛物线型莫尔包络线理论
抛物线型莫尔包络线理论的示意图如图 1, 用数学方程可表达为:
τ2=K2σI(σI−σ) (1) 式中:σI为岩石在各向等值拉伸条件下的抗张断裂极限, MPa; K为岩石粘结强度, MPa; τ、σ分别为断裂面上的临界剪应力和临界正应力, MPa。本文中规定, 正值表示拉力, 负值表示压力。
以主应力来表达, 抛物线型莫尔包络线准则可写成:
(σ1−σ3)2+2K2σI(σ1+σ3)=K2(4−K2σ2I) (2) 式中:σ1、σ3分别为发生断裂时最大和最小主应力, MPa。
1.2 断层与上拱力定量关系的理论推导与简单模拟
研究表明, 地壳深部一般应力状态为:
σ1=σ2=σ3=−ρgh (3) 式中:ρ表示岩体的密度, kg/cm3; g为重力加速度, m/s2; h表示深度, m;σ1, σ2, σ3分别表示最大主应力、中间主应力、最小主应力, MPa。
当忽略区域应力时, 上拱构造上覆地层只受到地下一般应力及上拱构造引起的上拱力和顺层附加应力共同作用。利用微积分理论和力学基本原理整合公式(1)-(3), 将岩层断裂时微观的莫尔包络线准则扩展到宏观背景下, 得出上拱力背景下, 正断层剖面形态与上拱力的定量关系式[7]:
dldh=√1+K24σI2+ρgh−σuwσI−K2σI√1+ρgh−σuwσI−K2σI√1+ρgh−σuwσI−K2σI√1+ρgh−σuwσI (4) 式中:l为水平距离, m;σuw为上拱力, MPa。
2. 三种盐上断层分布模式的数值模拟
盐拱构造具有典型的上拱力背景, 下文将以断层与上拱力定量关系理论为基础, 通过数值模拟的方法研究不同盐体形态及上拱力背景下盐上断层形态和分布模式。
塑性流动的盐体拱升, 形成作用于上覆岩层的上拱力, 从而使得上覆岩层形成褶皱或断层。随着研究的深入, 不同的形态的盐体逐渐得到认识并进行分类(见图 2)。按照盐构造形态, 可将其划分为整合型、过渡型、刺穿型和喷出型等4类, 其中比较典型的盐体形态包括盐滚、盐背斜、盐墙、盐盖、盐席、盐枕、盐球、盐焊接和盐株[9~17]。不同形态的盐体, 产生的上拱力的平面分布模式不同, 其形成的盐上正断层形态和分布模式也不同。因此, 可根据上拱力平面分布模式的差异, 将盐体形态分为三种典型类型:(1) 能产生恒定上拱力的盐体, 主要包括盐盖、盐席和其他呈面状展布的大型盐体; (2) 能产生线性分布上拱力的盐体, 主要包括盐滚和部分盐背斜、盐墙、盐舌、盐盖、盐席, 以及其他线形形态的盐体; (3) 能产生抛物线形上拱力的盐体, 主要包括盐球、盐枕、盐株、盐背斜、盐墙和部分盐盖、盐席, 以及其他拱形盐体形态。当然, 这种分类标准还仅局限于二维剖面, 对于同一盐体的不同剖面, 其形态与上拱力分布模式不同, 所产生的断层模式亦不尽相同。三维空间中断层形态和分布模式过于复杂, 本文不做讨论。
下文将针对这三种盐体类型, 分别定量拟合出上拱力分布模式, 并通过数值模拟, 总结不同上拱力背景下的断层形态和分布模式。
2.1 恒定上拱力断层模式
当盐构造呈水平面状(或近于面状)展布时, 其产生的上拱力亦可认为呈恒定大小、水平面状展布, 假定其大小为50 MPa, 且盐上岩层物性变化不大, 相关物性参数恒定:K=5 MPa; σI=0.4 MPa; ρ=2.8 g/cm3。结合这些参数及公式(4) 进行数值模拟。
模拟结果显示, 盐构造上部发育倾向相反的两组断层, 每组内断层相互平行, 所有断层形态和垂向分布一致, 单条断层无限延伸且倾角不断接近45度, 直至水平应力无法满足断裂极限应力要求而截止, 总体呈铲式(见图 3)。两组断层间可随意切割, 图 3显示的为自然界中较为常见的组合模式。
2.2 线性上拱力断层模式
当剖面中盐体形态呈近于线形的展布时, 其产生的上拱力亦可认为在地下呈线性变化。在此, 模拟相邻两个不同斜率线性变化上拱力背景, 上拱力变化关系为:
σuw=13.06×l(l≤3 km) (5) σuw=2.8×l+30.8(l≥3 km) (6) 式中, l为水平距离, 为了方便计算, 在本式及下文中, 均取其单位为km; σuw为上拱力, MPa。
假定, 盐上地层物性参数为:K=5 MPa; σI=0.2 MPa; ρ=2.8 g/cm3。把这些参数及公式(5)、(6) 带入公式(4), 进行数值模拟。
模拟结果显示, 在线性变化的上拱力背景下, 盐上地层发育两组深浅不一的断层, 倾向相反(见图 4)。每组断层形态一致, 与恒定上拱力断层模式中断层形态类似, 由竖直变为倾角无限接近45度, 呈铲式。每组内, 断层垂向分布深度随着上拱力变小而线性变深, 将断层开始发生断裂的点连成一条直线, 文中将其命名为起断线, 两组断层的起断线近于平行。考虑到自然界实际情况, 较浅一组断层或优先发育, 为主断层, 较深一组断层为次断层, 多被主断层限制。这是由于盐上地层被拱起而顺层拉升, 上部地层拉升幅度大于下部地层而使浅部断层易于发育, 且当次断层延伸至主断层附近时, 由地层拉伸产生的顺层应力容易被主断层错动而释放, 使次断层截止于主断层。图 4中左半部分到右半部分, 上拱力变化斜率减小, 形成的断层变陡且垂向分布变浅。
2.3 抛物线形上拱力断层模式
当剖面中盐体形态呈拱形, 可近似用抛物线模拟其产生的上拱力大小分布, 假定其表达式为:
σuw=−7×(l−2.5)2+44.8 (7) 盐上地层物性参数假定恒为:K=5 MPa; σI=0.2 MPa; ρ=2.8 g/cm3。把这些参数及公式(7) 带入公式(4), 进行数值模拟。
模拟结果显示, 主要有两组断层对称发育, 倾向均指向构造中心(见图 5)。每组断层中, 从构造边部到中心, 断层逐渐变陡和变浅。断层互相切割, 形成花状断层模式。而在断层边部还出现一组次级小断层, 倾向与该侧主断层相反, 具有类似形态, 垂向分布深度亦从构造中心到边部逐渐变深, 多被主断层限制, 与线性上拱力断层模型中次级断层类似。这类小断层可使盐上地层进一步断块化。
3. 实例论证与应用
自然界中盐底劈物质的剖面形态多呈不规则的凸起形态(见图 6), 在恒定大小、线性变化和抛物线形变化三种上拱力类型中, 实际底劈产生的上拱力多近似于抛物线形, 因而实际的盐上断层也多类似于抛物线形上拱力断层模式。图 6显示, 一些盐构造的实际断层形态和模式与抛物线型断层模式的数值模拟结果非常相似; 尽管不完全一致, 其原因是实际盐体形态、岩石性质等参数与数值模拟参数不完全相同, 且地震剖面没有经过时深转换。
德国Reitbrook盐拱构造盐上断层左侧发育反向小断层被主断层所限制, 与线性和抛物线型断层模式中次级小断层的特征非常类似(见图 7)。
图 7 Reitbrook盐底劈构造盐上断层模式[22]a—Reitbrook盐拱构造古近系底部构造图; b—Reitbrook盐拱构造的剖面图。红色框内为被主断层限制的反向小断层Figure 7. The pattern of upsalt fault of Reitbrook dome这些实例可很大程度地证实模拟基于的理论基础和模拟结果的可靠性。
4. 结论
不同形态的上拱盐体产生不同类型的上拱力, 据此将上拱盐构造分为三种类型:(1) 产生恒定上拱力的盐构造; (2) 产生线性分布上拱力的盐构造; (3) 产生抛物线形分布上拱力的盐构造。不同类型盐构造及上拱力背景, 产生的盐上断层的形态及分布模式亦不相同。数值模拟结果显示:(1) 在恒定上拱力断层模式中, 发育两组相对称的断层, 所有断层的形态和分布深度都一致; (2) 在线性上拱力断层模式中, 发育主次两组倾向相反的断层, 主断层组分布较浅, 次断层组分布较深, 每组断层内所有断层形态一致, 其分布随着上拱力减小而线性变深; (3) 在抛物线型断层模式中, 主要发育两组倾向相反相对称的断层, 从中间到两边, 断层倾角逐渐变缓, 分布变深, 而在构造侧翼发育次级小断层, 多被主断层限制。
与自然界中实际盐上断层相对比, 数值模拟结果(尤其抛物线型断层模式)与实际吻合较好, 证实了模拟的理论基础(即断层形态与上拱力的定量关系理论)、模拟过程和模拟结果的可靠性。盐上断层形态和分布模式是其下部盐体形态及上拱力分布情况的定量表现。本文数值模拟揭示的三种盐上断层分布模式及本文模拟所基于的断层形态与上拱力的定量关系理论, 可为构造解释中定性识别盐体形态, 定量预测上拱力大小及分布模式, 以及预测未发现断层(裂缝)形态和分布等提供可行的理论依据。
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图 5 Uemachi断裂二维剖面图[22]
Figure 5. The 2D profiles of the Uemachi fault
图 6 Christchurch city浅层地表二维雷达图像[26]
Figure 6. The profiles of GPR in Christchurch city
图 7 Sandhwal Village地区处理后频率为200 MHz的2D和3D地质雷达图像[34]
Figure 7. Processed 2D and 3D GPR profiles collected using 200 MHz antenna across the HF2 scarp at Sandhwal Village
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[1] Zhao W K, Emanuele F, Sara T L, et al. Improved high-resolution GPR imaging and characterization of prehistoric archaeological features by means of attribute analysis[J]. Journal of Archaeological Science, 2015, 54: 77~85. doi: 10.1016/j.jas.2014.11.033 [2] Böniger* U, Tronicke J. Improving the interpretability of 3D GPR data using target-specific attributes: Application to tomb detection[J]. Journal of Archaeological Science, 2010, 37: 672~679. doi: 10.1016/j.jas.2010.01.013 [3] Hiroko O, Youngjoo K, Toru T. Depositional and erosional architectures of gravelly braid bar formed by a flood in the Abe River, central Japan, inferred from a three-dimensional ground-penetrating radar analysis[J]. Sedimentary Geology, 2015, 324: 32~46. doi: 10.1016/j.sedgeo.2015.04.008 [4] Li X J, Hu Z Q, Li S C, et al. Anomalies of mountainous mining paddy in western China[J]. Soil & Tillage Research, 2015, 145: 10~19. http://www.sciencedirect.com/science/article/pii/S0167198714001585 [5] Mercedes S, Higinio G G, Henrique L, et al. Uncertainty evaluation of the 1 GHz GPR antenna for the estimation of concrete asphalt thickness[J]. Measurement, 2013, 46: 3032~3040. doi: 10.1016/j.measurement.2013.06.022 [6] Arias P, Armesto J, Capua D D, et al. Digital photogrammetry, GPR and computational analysis of structural damages in a mediaeval bridge[J]. Engineering Failure Analysis, 2007, 14: 1444~1457. doi: 10.1016/j.engfailanal.2007.02.001 [7] Brosten T R, Bradford J H, McNamara J P, et al. Estimating 3D variation in active-layer thickness beneath arctic streams using ground-penetrating radar[J]. Journal of Hydrology, 2009, 73: 479~486. http://www.sciencedirect.com/science/article/pii/S0022169409003102 [8] Andrea B. Water content evaluation in unsaturated soil using GPR signal analysis in the frequency domain[J]. Journal of Applied Geophysics, 2010, 71: 26~35. doi: 10.1016/j.jappgeo.2010.03.001 [9] Pitambar P, Parkash B, Awasthi A K, et al. Concealed thrusts in the Middle Gangetic plain, India: A ground penetrating radar study proves the truth against the geomorphic features supporting normal faulting[J]. Journal of Asian Earth Sciences, 2011, 40: 315~325. doi: 10.1016/j.jseaes.2010.06.012 [10] Malik J N, Shah A A, Sahoo A K, et al. Active fault, fault growth and segment linkage along the Janauri anticline (frontal foreland fold), NW Himalaya, India[J]. Tectonophysics, 2010, 483: 327~343. doi: 10.1016/j.tecto.2009.10.028 [11] Mike D, Adam O, Dan C. Ground penetrating radar as a means of studying palaeofault scarps in a deeply weathered terrain, southwestern Western Australia[J]. Journal of Applied Geophysics, 2010, 72: 92~101. doi: 10.1016/j.jappgeo.2010.07.005 [12] Liberty L, Hemphill-Haley M A, Madin I P. The Portland Hills Fault: Uncovering a hidden fault in Portland, Oregon using high-resolution geophysical methods[J]. Tectonophysics, 2003, 368: 89~103. doi: 10.1016/S0040-1951(03)00152-5 [13] 杨峰, 彭苏萍.地质雷达探测原理与方法研究[M].北京:科学出版社, 2006.YANG Feng, PENG Su-ping. Principles and Methods of Ground penetrating radar[M]. Beijing: Sciences Press, 2006. [14] 曾昭发, 刘四新, 冯晅, 等.探地雷达原理与应用[M].北京:电子工业出版社, 2010.ZENG Zhao-fa, LIU Si-xin, FENG Xuan, et al. The principle and application of Ground Penetrating Radar[M]. Beijing: Electronics Industry Press, 2010. [15] Fisher E, McMechan G A, Annan A P. Acquisition and processing of wide-aperture ground penetrating radar data[J]. Geophysics, 1992, 57: 495. doi: 10.1190/1.1443265 [16] Grasmueck M. 3-D ground-penetrating radar applied to fracture imaging in gneiss[J]. Geophysics, 1996, 61: 1050~1064. doi: 10.1190/1.1444026 [17] 李树德.活动断层分段研究[J].北京大学学报:自然科学版, 1999, 35(6):768~773. http://www.cnki.com.cn/Article/CJFDTOTAL-BJDZ199906006.htmLI Shu-de. Study on segmentation of active faults[J]. Act a Scicentiarum Naturalum Universitis Pekinesis, 1999, 35(6): 768~773. http://www.cnki.com.cn/Article/CJFDTOTAL-BJDZ199906006.htm [18] 徐锡伟.活动断层、地震灾害与减灾对策问题[J].震灾防御技术, 2006, 1(1):7~13. doi: 10.11899/zzfy20060102XU Xi-wei. Active faults, associated earthquake disaster distribution and policy for disaster reduction[J]. Technology for Earthquake Disaster Prevention, 2006, 1(1): 7~13. doi: 10.11899/zzfy20060102 [19] 沈建文, 蔡长青.地震危险性分析与抗震设防标准的确定[J].地震工程与工程振动, 1997, 17(2):27~36. http://www.cnki.com.cn/Article/CJFDTOTAL-DGGC702.004.htmSHEN Jian-wen, CAI Chang-qing. Seismic hazard analysis and earthquake resistant level[J]. Earthquake Engineering and Engineering Vibration, 1997, 17(2): 27~36. http://www.cnki.com.cn/Article/CJFDTOTAL-DGGC702.004.htm [20] Audrua J C, Banob M, Beggc J, et al. GPR investigations on active faults in urban areas: The Georisc-NZ project in Wellington, New Zealand[J]. Earth and Planetary Sciences. 2001, 333: 447~454. http://www.academia.edu/3381673/GPR_investigations_on_active_faults_in_urban_areas_the_Georisc-NZ_project_in_Wellington_New_Zealand [21] Slater L, Niemi T M. Ground-penetrating radar investigation of active faults along the Dead Sea Transform and implications for seismic hazardswithin the city of Aqaba, Jordan[J]. Tectonophysics, 2003, 368: 33~50. doi: 10.1016/S0040-1951(03)00149-5 [22] Rasheda M, Kawamuraa D, Nemotoa H, et al. Ground penetrating radar investigations across the Uemachi fault, Osaka, Japan[J]. Journal of Applied Geophysics, 2003, 53: 63~75. doi: 10.1016/S0926-9851(03)00028-4 [23] Rasheda M, Kawamuraa D. High-resolution shallow seismic and ground penetrating radarinvestigations revealing the evolution of the Uemachi Fault system, Osaka, Japan[J]. The Island Arc, 2004, 13: 144~156. doi: 10.1111/iar.2004.13.issue-1 [24] Libertya L M, Hemphill-Haley M A, Madinc I P. The Portland Hills Fault: uncovering a hidden fault in Portland, Oregon using high-resolution geophysical methods[J]. Tectonophysics, 2003, 368: 89~103. doi: 10.1016/S0040-1951(03)00152-5 [25] khorsandi A, Abdali M, Miyata T, et al. Application of GPR Method Due to Active Faults Determination in Urban Area, Case Study: North Shahre Ray Fault, South of Tehran, Iran[C]. 2011 International Conference on Environment Science and Engineering, 2011. [26] Carpentier S F, Green A G, Doetsch J, et al. Recent deformation of Quaternary sediments as inferred from GPR images and shallow P-wave velocity tomograms: Northwest Canterbury Plains, New Zealand[J]. Journal of Applied Geophysics, 2012, 81:2~15. doi: 10.1016/j.jappgeo.2011.09.007 [27] 薛建, 贾建秀, 黄航, 等.应用探地雷达探测活动断层[J].吉林大学学报(地球科学版), 2008, 38(2):347~350.XUE Jian, JIA Jian-xiu, HUANG Hang, et al. Application of GPR in Active Fault Detection[J]. Journal of Jilin University(Earth Science Edition), 2008, 38(2):347~350. [28] 薛建, 黄航, 张良怀.探地雷达方法探测与评价长春市活动断层[J].物探与化探.2009, 33(1):63~66.XUE Jian, HUANG Hang, ZHANG Liang-huai. The Application of the GPR Method to Detecting and Estimating Active Faults in Changchun[J]. GEOPHYSICAL & GEOCHEM ICAL EXPLORATION. 2009, 33(1): 63~66. [29] 崔国柱, 李恩泽, 曾昭发.活动断层与地球物理方法[J].世界地质, 2003.22(2):185~190. http://www.cnki.com.cn/Article/CJFDTOTAL-SJDZ200302015.htmCUI Guo-zhu, LI Ee-ze, ZENG Zhao-fa. Active Fault and Geophysical Methods[J]. Global Geology, 2003, 22(2): 185~190. http://www.cnki.com.cn/Article/CJFDTOTAL-SJDZ200302015.htm [30] 李征西, 曾昭发, 李恩泽, 等.地球物理方法探测活动断层效果和方法最佳组合分析[J].吉林大学学报(地球科学版), 2005, 35:110~114. http://www.cnki.com.cn/Article/CJFDTOTAL-CCDZ2005S1023.htmLI Zheng-xi, ZENG Zhao-fa, LI Ee-ze, et al. The Function of Geophysical Method in Active Fault Detection and Discuss of Combining Methods[J]. Journal of Jilin University (Earth Science Edition). 2005, 35: 109~224. http://www.cnki.com.cn/Article/CJFDTOTAL-CCDZ2005S1023.htm [31] 李建军, 张军龙.探地雷达在探测潜伏活动断层中的应用[J].地震, 2015, 35(4):83~89.LI Jian-jun, ZHANG Jun-long. Application of GPR in Surveying Underlied Active Faults[J]. EARTHQUAKE, 2015, 35(4): 83~89. [32] Salvi S, Cinti F R, Colini L, et al. Investigation of the active Celano-L'Aquila fault system, Abruzzib(central Apennines, Italy) with combined ground-penetrating radarand palaeoseismic trenching[J]. Geophys. J. Int. 2003, 155: 805~811. doi: 10.1111/gji.2003.155.issue-3 [33] Anderson K B, Spotila J A, Hole J A. Application of geomorphic analysis and ground-penetrating radar to characterization of paleoseismic sites in dynamic alluvial environments: an example from southern California[J]. Tectonophysics, 2003, 368: 25~32. doi: 10.1016/S0040-1951(03)00148-3 [34] Malik J N, Kumar A, Satuluri S, et al. Ground-Penetrating Radar Investigations along Hajipur Fault: Himalayan Frontal Thrust—Attempt to Identify Near Subsurface Displacement, NWHimalaya, India[J]. International Journal of Geophysics, 2012. https://www.hindawi.com/journals/ijge/2012/608269/abs/ [35] Cahit C Y, Erhan A, Maksim B, et al. Application of GPR to normal faults in the Buyuk Menderes Graben, western Turkey[J]. Journal of Geodynamics, 2013, 65: 218~227. doi: 10.1016/j.jog.2012.05.011 [36] Chow J, Angelier J, Hua J, et al. Paleoseismic event and active faulting:from ground penetrating radar and high-resolution seismic reflection profiles across the Chihshang Fault. eastern Taiwan[J]. Tectonophysics, 2001, 33: 241~259. http://www.sciencedirect.com/science/article/pii/S0040195100002778 [37] Dentith M A O, Clark D. Ground penetrating radar as a means of studying palaeofault scarps in a deeply weathered terrain, southwestern Western Australia[J]. Journal of Applied Geophysics, 2010, 72: 92~101. doi: 10.1016/j.jappgeo.2010.07.005 [38] Ercoli M, Pauselli C, Frigeri A, et al. 2D AND 3D GROUND PENETRATING RADAR (GPR) CAN IMPROVE PALEOSEISMOLOGICAL RESEARCHES: AN EXAMPLE FROM THE MT. VETTORE FAULT (CENTRAL APPENNINES, ITALY)[C], GNGTS 2011. [39] Ercoli M, Pauselli C, Frigeri A, et al. 2D-3D GPR signature of shallow faulting in the Castelluccio di Norcia basin (Central Italy)[C]. EGU General Assembly, 2012. [40] Gross R, Green A, Holliger K, et al. Shallow geometry and displacements on the San Andreas Fault near Point Arena based on trenching and 3-D georadar surveying[J]. GEOPHYSICAL RESEARCH LETTERS 2002, 29. http://adsabs.harvard.edu/abs/2002GeoRL..29t..34G [41] Cristina P, Costanzo F, Alessandro F, et al. Ground penetrating radar investigation to study active faults in the Norcia Basin (central Italy)[J]. Journal of Applied Geophysics, 2010, 72: 39~45. doi: 10.1016/j.jappgeo.2010.06.009 [42] 张迪, 李家存, 吴中海, 等.探地雷达在探测玉树走滑断裂带活动性中的初步应用[J].地质通报, 2015, 34(1):204~216.ZHANG Di, LI Jia-cun, WU Zhong-hai, et al. A preliminary application of ground penetrating radar to the detection of active faults along Yushu strike-slip faulted zone. Geological Bulletin of China, 2015, 34(1): 204~216. [43] 栗毅, 黄春琳, 雷文太.探地雷达理论与应用[M].北京:科学出版社, 2011.LI Yi, HUANG Chun-lin, LEI Wen-tai. Ground Penetrating Radar: Theory and Applications[M]. Beijing: Sciences Press, 2011. [44] Millard S G, Shaw M R, Giannopoulos A, et al. Modeling of subsurface pulsed radar for nondestructive testing of structures[J]. ASCE J Mater Civil Eng 1998, 10: 96~188. doi: 10.1061/%28ASCE%290899-1561%281998%2910%3A3%28188%29 [45] Maurizio E, Cristina P, Alessandro F, et al. "Geophysical paleoses-mology" through high resolution GPR data: A case of shallow faulting imaging in Central Italy[J]. Journal of Applied Geophysics, 2013, 90: 27~40. doi: 10.1016/j.jappgeo.2012.12.001 [46] Green A G, Gross R, Holliger K, et al. Results of 3-D georadar surveying and trenching the San Andreas fault near its northern landward limit[J]. Tectonophysics, 2003, 368: 7~23. doi: 10.1016/S0040-1951(03)00147-1 [47] Gross R, Green A G, Horstmeyer H, et al. 3-D georadar images of an active fault: efficient data acquisition, processing and interpretation strategies[J]. Subsurface Sensing Technologies and Applications, 2003, 4 (1): 19~40. doi: 10.1023/A:1023059329899 [48] Vanneste K, Verbeeck K, Petermans T. Pseudo-3D imaging of a low-slip-rate active normal fault using shallow geophysical methods: the Geleen fault in the Belgian Mass River valley[J]. Geophysics, 2008, 73 (1): B1~B9. http://adsabs.harvard.edu/abs/2008Geop...73B...1V [49] McClymont A F, Green A G, Kaiser A, et al. Shallow fault segmentation of the Alpine fault zone, New Zealand revealed from 2-and 3-D GPR surveying[J]. Journal of Applied Geophysics, 2010, 70 (4): 343~354. doi: 10.1016/j.jappgeo.2009.08.003 [50] Carpentier S F A, Green A G, Langridge R. et al. Flower structures and Riedel shears at a step over zone along the Alpine Fault (New Zealand) inferred from 2-D and 3-D GPR images[J]. Journal of Geophysical Research, 2012:117. doi: 10.1029/2011JB008749/full#footer-citing -