基于优化滤波法对芦山地震震区重力异常特征的分析
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摘要
首先对具有代表性的重力异常分离方法进行简单介绍,在此基础上使用这些方法对同一组理论模型数据进行试验,优选出异常分离效果较好的优化滤波法对芦山地震震区重力异常特征进行分析,初步认识此次地震发生的深部构造背景,得出以下初步结论:龙门山断裂带在研究区布格重力异常中反映为一条近北东走向的显著重力梯度带.该梯度带在天全附近分为两支,芦山地震震区靠近重力梯度带分叉处,且MS≥3.0余震同样呈近北东向展布,与梯度带走向基本一致,认为此次强地震的发生与重力梯度带下的深部结构及构造活动密切相关;芦山地震震区浅部结构与深部构造特征存在较大差异,构造复杂及地壳深浅部耦合关系较差,说明此次强地震的发生受浅部和深部构造的共同控制.
This paper firstly introduces the gravity anomaly separation methods,then adopts the preferential filtering method to analyze the characteristic of gravity field in the Lushan earthquake zone and its adjacent areas,so as to shed some lights on the tectonic background of the earthquake in the subsurface.The preliminary understandings are:① A remarkable gravity gradient zone(GGZ)trending NE presents along the Longmenshan faults zone,and to the south of Tianquan county it is splitted into two branches;② The epicenter of this earthquake is near the crotch of the GGZ,and the aftershocks with MS≥3.0 strike NE,which is consistent with the strike of the GGZ.All the results indicate thatthe generation of this earthquake is closely related to the deep structure and tectonic activities beneath the GGZ.There is a large difference between shallow structures and deep ones in Lushan earthquake zone,in addition,complex structures as well as poor coupling between shallow and deep part of the crust also exist,implying the generation of Lushan earthquake was controlled by both shallow and deep structures.
This paper firstly introduces the gravity anomaly separation methods,then adopts the preferential filtering method to analyze the characteristic of gravity field in the Lushan earthquake zone and its adjacent areas,so as to shed some lights on the tectonic background of the earthquake in the subsurface.The preliminary understandings are:① A remarkable gravity gradient zone(GGZ)trending NE presents along the Longmenshan faults zone,and to the south of Tianquan county it is splitted into two branches;② The epicenter of this earthquake is near the crotch of the GGZ,and the aftershocks with MS≥3.0 strike NE,which is consistent with the strike of the GGZ.All the results indicate thatthe generation of this earthquake is closely related to the deep structure and tectonic activities beneath the GGZ.There is a large difference between shallow structures and deep ones in Lushan earthquake zone,in addition,complex structures as well as poor coupling between shallow and deep part of the crust also exist,implying the generation of Lushan earthquake was controlled by both shallow and deep structures.
引文
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郭良辉,孟小红,石磊.2010.磁异常ΔT三维相关成像[J].地球物理学报,53(2):435--441.
侯遵泽,杨文采.1997.中国重力异常的小波变换与多尺度分析[J].地球物理学报,40(1):85--95.
楼海,王椿镛,吕志勇,姚志祥,戴仕贵,尤慧川.2008.2008年汶川MS8.0级地震的深部构造环境:远震P波接收函数和布格重力异常的联合解释[J].中国科学:D辑,38(10):1207--1220.
王有学,Mooney W D,韩果花,袁学诚,姜枚.2005.台湾—阿尔泰地学断面阿尔金—龙门山剖面的地壳纵波速度结构[J].地球物理学报,48(1):98--106.
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许志琴,李化启,侯立炜,付小芳,陈文,曾令森,蔡志慧,陈方远.2007.青藏高原东缘龙门—锦屏造山带的崛起:大型拆离断层和挤出机制[J].地质通报,26(10):1262--1267.
杨文采,施志群,侯遵泽.2001.离散小波变换与重力异常多重分界[J].地球物理学报,44(4):534--541.
曾华霖.2005.重力场与重力勘探[M].北京:地质出版社:189--234.
张培震,徐锡伟,闻学泽,冉勇康.2008.2008年汶川8.0级地震发震断裂的滑动速率、复发周期和构造成因[J].地球物理学报,51(4):1066--1073.
张勇,许力生,陈运泰.2013.芦山4·20地震破裂过程及其致灾特征初步分析[J].地球物理学报,56(4):1408--1411.
朱介寿.2008.汶川地震的岩石圈深部结构与动力学背景[J].成都理工大学学报:自然科学版,35(4):348--356.
Clarke G K C.1969.Optimum second-derivative and downward-continuation filters[J].Geophysics,34:424--437.
Chen Z,Burchfiel B C,Liu Y,King R W,Royden L H,Tang W,Wang E,Zhao J,Zhang X.2000.Global positioning system measurements from eastern Tibet and their implications for India/Eurasia intercontinental deformation[J].J Geophys Res,105:16215--16227.
Fedi M,Quarta T.1998.Wavelet analysis of the regional-residual and local separation of potential field anomalies[J].Geophysical Prospecting,46:507--525.
Guo L H,Meng X H,Chen Z X,Li S L,Zheng Y M.2013.Preferential filtering for gravity anomaly separation[J].Computers&Geosciences,51:247--254.
Keating P,Pinet N.2011.Use of non-linear filtering for the regional-residual separation of potential field data[J].J Appl Geophys,19:315--322.
Meng X H,Guo L H,Chen Z X,Li S L,Shi L.2009.A method for gravity anomaly separation based on preferential continuation and its application[J].Applied Geophysics,6(3):217--225.
Naudy H,Dreyer H.1968.Essai de filtrage non-linéaire appliquéaux profils aéromagnétiques[J].Geophysical Prospecting,16(2):171--178.
Nikitin A A,Vasov O K,Belov A P.1984.Vozmozhnosti kompleksnoy geofizicheskoy interpretatsii na baze entropiynogo fil'tra.Izvestiya Akademii Nauk Turkmenskoy SSR[J].Seriya Fiziko-Tekhnicheskikh,Khimicheskikhi Geologicheskikh Nauk,2:79--82.
Pawlowski R S.1995.Preferential continuation for potential-field anomaly enhancement[J].Geophysics,60(2):390--398.
Ward S,Mikhail K,Fred B,Magdala T,Walter D M,Sierd C.2013.High resolution regional crustal models from irregularly distributed data:Application to Asia and adjacent areas[J].Tectonophysics,602:55--68.
Wiener N.1949.Extrapolation,Interpolation,and Smoothing of Stationary Time Series[M].New York:John Wiley&Sons Inc:1--24.
Zhang J S,Gao R,Zeng L S,Li Q S,Guan Y,He R Z,Wang H Y,Lu Z W.2010.Relationship between characteristics of gravity and magnetic anomalies and the earthquakes in the Longmenshan range and adjacent areas[J].Tectonophysics,491(1/4):218--229.
郭良辉,孟小红,石磊.2010.磁异常ΔT三维相关成像[J].地球物理学报,53(2):435--441.
侯遵泽,杨文采.1997.中国重力异常的小波变换与多尺度分析[J].地球物理学报,40(1):85--95.
楼海,王椿镛,吕志勇,姚志祥,戴仕贵,尤慧川.2008.2008年汶川MS8.0级地震的深部构造环境:远震P波接收函数和布格重力异常的联合解释[J].中国科学:D辑,38(10):1207--1220.
王有学,Mooney W D,韩果花,袁学诚,姜枚.2005.台湾—阿尔泰地学断面阿尔金—龙门山剖面的地壳纵波速度结构[J].地球物理学报,48(1):98--106.
熊小松.2010.中国大陆莫霍面深度与变化特征及其地球动力学意义[D].北京:中国地质科学院:1--200.
许德树,曾华霖.2000.优选延拓技术及其在中国布格重力异常图处理上的应用[J].现代地质,14(2):215--222.
许志琴,李化启,侯立炜,付小芳,陈文,曾令森,蔡志慧,陈方远.2007.青藏高原东缘龙门—锦屏造山带的崛起:大型拆离断层和挤出机制[J].地质通报,26(10):1262--1267.
杨文采,施志群,侯遵泽.2001.离散小波变换与重力异常多重分界[J].地球物理学报,44(4):534--541.
曾华霖.2005.重力场与重力勘探[M].北京:地质出版社:189--234.
张培震,徐锡伟,闻学泽,冉勇康.2008.2008年汶川8.0级地震发震断裂的滑动速率、复发周期和构造成因[J].地球物理学报,51(4):1066--1073.
张勇,许力生,陈运泰.2013.芦山4·20地震破裂过程及其致灾特征初步分析[J].地球物理学报,56(4):1408--1411.
朱介寿.2008.汶川地震的岩石圈深部结构与动力学背景[J].成都理工大学学报:自然科学版,35(4):348--356.
Clarke G K C.1969.Optimum second-derivative and downward-continuation filters[J].Geophysics,34:424--437.
Chen Z,Burchfiel B C,Liu Y,King R W,Royden L H,Tang W,Wang E,Zhao J,Zhang X.2000.Global positioning system measurements from eastern Tibet and their implications for India/Eurasia intercontinental deformation[J].J Geophys Res,105:16215--16227.
Fedi M,Quarta T.1998.Wavelet analysis of the regional-residual and local separation of potential field anomalies[J].Geophysical Prospecting,46:507--525.
Guo L H,Meng X H,Chen Z X,Li S L,Zheng Y M.2013.Preferential filtering for gravity anomaly separation[J].Computers&Geosciences,51:247--254.
Keating P,Pinet N.2011.Use of non-linear filtering for the regional-residual separation of potential field data[J].J Appl Geophys,19:315--322.
Meng X H,Guo L H,Chen Z X,Li S L,Shi L.2009.A method for gravity anomaly separation based on preferential continuation and its application[J].Applied Geophysics,6(3):217--225.
Naudy H,Dreyer H.1968.Essai de filtrage non-linéaire appliquéaux profils aéromagnétiques[J].Geophysical Prospecting,16(2):171--178.
Nikitin A A,Vasov O K,Belov A P.1984.Vozmozhnosti kompleksnoy geofizicheskoy interpretatsii na baze entropiynogo fil'tra.Izvestiya Akademii Nauk Turkmenskoy SSR[J].Seriya Fiziko-Tekhnicheskikh,Khimicheskikhi Geologicheskikh Nauk,2:79--82.
Pawlowski R S.1995.Preferential continuation for potential-field anomaly enhancement[J].Geophysics,60(2):390--398.
Ward S,Mikhail K,Fred B,Magdala T,Walter D M,Sierd C.2013.High resolution regional crustal models from irregularly distributed data:Application to Asia and adjacent areas[J].Tectonophysics,602:55--68.
Wiener N.1949.Extrapolation,Interpolation,and Smoothing of Stationary Time Series[M].New York:John Wiley&Sons Inc:1--24.
Zhang J S,Gao R,Zeng L S,Li Q S,Guan Y,He R Z,Wang H Y,Lu Z W.2010.Relationship between characteristics of gravity and magnetic anomalies and the earthquakes in the Longmenshan range and adjacent areas[J].Tectonophysics,491(1/4):218--229.
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