preliminary discussion on horizontal gravity gradient and its application to seismic gravity precursor research

doi:10.3969/j.issn.0253-4967.2015.04.007

Abstract

Abstract:

In this paper, according to the synthetic gravity anomaly of a horizontally infinite cylindrical geologic body, gravity gradient in horizontal direction was calculated by potential field discrete cosine transformation in frequency domain. In the calculation, the minimum curvature method was used to extend edge lines. We found that the gravity gradient field from the potential field transformation was dependable by comparison with synthetic gravity gradient, except the data in the edges. Then, the accumulative horizontal gravity gradients before Lushan M_S7.0 earthquake were calculated for the accumulative gravity anomaly from September 2010 to October 2012. In the north-south direction, gravity gradient in Daofu-Kangding-Shimian and Markang-Lixian-Lushan exhibited a positive high value, and the strike of the high value zone was in line with the strike of Xianshuihe Faults and Markang Faults. In the east-west direction, high value zone was not as obvious as that in the north-south direction. Gravity gradients in the direction along and vertical to the strike of Longmenshan Faults were calculated by the definition of directional derivative. In the along-strike direction, high gravity gradient values appeared in Markang-Lixian areas along Markang Faults and Daofu-Kangding-Shimian areas along Xianshuihe Faults, and extremum appeared in Kangding-Shimian and the area nearby Lixian. In the direction vertical to the strike of Longmenshan fault zone, high gravity gradient values appeared in Lixian-Lushan-Kangding-Shimian areas, and the extremum appeared in the area nearby Kangding. The results indicate that gravity gradient in the direction along and vertical to the strike of faults can better show the relative gravity change on the two sides of faults. Lushan M_S7.0 earthquake is located at the transition zone between the two high value zones of gravity gradient. The total horizontal gravity gradient shows that the location and strike of the high value zone are basically consistent with regional faults, and the extremums of total horizontal gravity gradient appeared nearby Lixian, Kangding and Shimian.

Key words: field potential transformation, gravity anomaly, Lushan M_S7.0 earthquake, gravity gradient, directional derivative

摘要：

首先根据水平无限长圆柱形地质体的理论重力异常, 在频率域使用余弦变换法, 通过位场变换计算了水平方向的重力梯度, 并与理论重力梯度做比较, 发现余弦变换法计算得到的水平重力梯度是可靠的。其次, 使用频率域中的余弦变换法计算了2010年9月至2012年10月芦山地震前的累积重力水平梯度, 并求得沿龙门山断裂带走向和垂向的重力水平梯度。结果表明: 沿断裂带走向和垂向的重力梯度能够以明显的条带状更好地显现出重力在断裂两侧的相对变化, 并且芦山震中位于重力梯度高值区的中间地带; 重力水平总梯度变化显示, 在理县—芦山一带、康定—石棉一带为重力梯度高值区, 且高值区位置及走向与区域断裂构造基本重合, 并在理县、康定以及石棉附近重力水平梯度值为极值区。

关键词: 位场变换, 重力异常, 芦山M_S7.0地震, 重力梯度, 方向导数

CLC Number:

P315.72⁺6

ZHAO Yun-feng, ZHU Yi-qing, LIU Fang. preliminary discussion on horizontal gravity gradient and its application to seismic gravity precursor research[J]. SEISMOLOGY AND GEOLOGY, 2015, 37(4): 1020-1029.

赵云峰, 祝意青, 刘芳. 重力水平梯度及其在地震重力前兆中的研究初探[J]. 地震地质, 2015, 37(4): 1020-1029.

References

陈运泰, 顾浩鼎, 卢造勋. 1980. 1975年海城地震与1976年唐山地震前后的重力变化［J］. 地震学报, 2(1): 21—31.
CHEN Yun-tai, GU Hao-ding, LU Zao-xun. 1980. Vatiations of gravity before and after the Haicheng earthquake, 1975 and the Tangshan earthquake, 1976 ［J］. Acta Seismologica Sinica, 2(1): 21—31(in Chinese).
刘代芹, 王晓强, 李杰, 等. 2009. 新疆南天山地区重力场动态演化特征［J］. 西北地震学报, 31(2): 174—178.
LIU Dai-qin, WANG Xiao-qiang, LI Jie, et al. 2009. The dynamic evolution features of gravity field in southern Tianshan area, Xinjiang ［J］. Northewstern Seismological Journal, 31(2): 174—178(in Chinese).
刘东甲, 余海龙, 李海侠. 2012. 对《基于离散余弦变换的磁位谱分析及磁异常导数计算方法》一文的评论［J］. 地球物理学进展, 27(5): 1004—2903.
LIU Dong-jia, YU Hai-long, LI Hai-xia. 2012. Comment on "Magnetic potential spectrum analysis and calculating method of magnetic anomaly derivatives based on discrete cosine transform" ［J］. Progress in Geophys, 27(5): 1004—2903(in Chinese).
卢造勋, 方昌流, 石作亭, 等. 1978. 重力变化与海城地震［J］. 地球物理学报, 21(1): 1—8.
LU Zao-xun, FANG Chang-liu, SHI Zuo-ting, et al. 1978. Variation of the gravity field and the Haicheng earthquake ［J］. Acta Geophysica Sinica, 21(1): 1—8(in Chinese).
蒋甫玉, 黄岩, 燕轲. 2012. 由重力异常计算重力全梯度张量的余弦变换法［J］. 应用地球物理, 9(3): 247—260.
JIANG Fu-yu, HUANG Yan, YAN Ke. 2012. Full gravity gradient tensors from vertical gravity by cosine transform ［J］. Applied Geophysics, 9(3): 247—260(in Chinese).
申重阳, 李辉, 付广裕. 2003. 丽江7.0级地震重力前兆模式研究［J］. 地震学报, 25(2): 163—171.
SHEN Chong-yang, LI Hui, FU Guang-yu. 2003. Study on a gravity precursor mode of Lijiang earthquake with M_S7.0 ［J］. Acta Seismologica Sinica, 25(2): 163—171(in Chinese).
王谦身, 腾吉文, 张永谦, 等. 2013. 中秦岭地带重力异常特征及地壳结构的探榷［J］. 地球物理学报, 56(12): 3999—4008.
WANG Qian-shen, TENG Ji-wen, ZHANG Yong-qian, et al. 2013. Discussion on the gravity anomalies and crustal structure of the Middle Qinling Mountains ［J］. Chinese J Geophys, 56(12): 3999—4008(in Chinese).
王万银, 邱之云, 刘金兰, 等. 2009. 位错数据处理中的最小曲率扩边和补空方法研究［J］. 地球物理学进展, 24(4): 1327—1338.
WANG Wan-yin, QIU Zhi-yun, LIU Jin-lan, et al. 2009. The research to the extending edge and interpolation based on the minmum curvature method in potential field data processing ［J］. Progress in Geophysics, 24(4): 1327—1338(in Chinese).
张凤旭, 孟玲顺, 张凤琴, 等. 2006. 重力位谱分析及重力异常导数换算新方法: 余弦变换［J］. 地球物理学报, 49(1): 244—248.
ZHANG Feng-xu, MENG Ling-shun, ZHANG Feng-qin, et al. 2006. A new method for spectral analysis of the potential field and conversion of derivative of gravity anomalies: Cosine transform ［J］. Chinese J Geophys, 49(1): 244—248(in Chinese).
张季生, 高锐, 曾令森, 等. 2009. 龙门山及其邻区重、磁异常特征与地震关系的研究［J］. 地球物理学报, 52(2): 572—578.
ZHANG Ji-sheng, GAO Rui, ZENG Ling-sen, et al. 2009. Relationship between characteristics of gravity and magnetic anomalies and the earthquakes in Longmenshan Range and adjacent areas ［J］. Chinese J Geophys, 52(2): 572—578(in Chinese).
张永志, 梁伟锋, 祝意青. 1999. 丽江7.0级地震过程的重力变化与小波分析［J］. 西北地震学报, 21(2): 149—155.
ZHANG Yong-zhi, LIANG Wei-feng, ZHU Yi-qing. 1999. The relationship between wavelet transformation results of gravity vatiation and the Lijiang M_S7.0 earthquake ［J］. Northewstern Seismological Journal, 21(2): 149—155(in Chinese).
张永志, 夏朝龙, 王卫东, 等. 2013. 日本9.0级地震区重力梯度的时空分布［J］. 大地测量与地球动力学, 33(6): 1—4.
ZHANG Yong-zhi, XIA Chao-long, WANG Wei-dong, et al. 2013. Temporal and spatial distribution of gravity gradients in Japan M_W9.0 earthquake area ［J］. J Geodesy and Geodynamics, 33(6): 1—4(in Chinese).
祝意青, 徐云马, 梁伟锋. 2008a. 2008年新疆于田M_S7.3地震的中期预测［J］. 大地测量与地球动力学, 28(5): 13—15.
ZHU Yi-qing, XU Yun-ma, LIANG Wei-feng. 2008a. Medium-term prediction of Yutian, Xinjiang M_S7.3 earthquake in 2008 ［J］. J Geodesy and Geodynamics, 28(5): 13—15(in Chinese).
祝意青, 梁伟锋, 徐云马. 2008b. 重力资料对2008年汶川M_S8.0地震的中期预测［J］. 国际地震动态, (7): 36—39.
ZHU Yi-qing, LIANG Wei-feng, XU Yun-ma. 2008b. Medium-term prediction of M_S8.0 earthquake in Wenchuan, Sichuan by mobile gravity ［J］. Recent Developments in World Seismology, (7): 36—39(in Chinese).
祝意青, 郭树松, 刘芳. 2010a. 攀枝花6.1、姚安6.0级地震前后区域重力场变化［J］. 大地测量与地球动力学, 30(4): 8—11.
ZHU Yi-qing, GUO Shu-song, LIU Fang. 2010a. Variation of gravity field before and after Panzhihua M_S6.1 and Yaoan M_S6.0 earthquakes ［J］. J Geodesy and Geodynamics, 30(4): 8—11(in Chinese).
祝意青, 梁伟锋, 徐云马, 等. 2010b. 汶川M_S8.0地震前后的重力场动态变化［J］. 地震学报, 32(6): 633—640.
ZHU Yi-qing, LIANG Wei-feng, XU Yun-ma, et al. 2010b. Dynamic variation of gravity field before and after Wenchuan M_S8.0 earthquake ［J］. Acta Seismologica Sinica, 32(6): 633—640(in Chinese).
祝意青, 闻学泽, 孙和平, 等. 2013. 2013年四川芦山M_S7.0地震前的重力变化［J］. 地球物理学报, 56(6): 1887—1894.
ZHU Yi-qing, WEN Xue-ze, SUN He-ping, et al. 2013. Gravity changes before the Lushan, Sichuan, M_S7.0 earthquake of 2013 ［J］. Chinese J Geophys, 56(6): 1887—1894(in Chinese).
Hu M, Li J, Li H, et al. 2014. Bathymetry predicted from vertical gravity gradient anomalies and ship soundings ［J］. Geodesy and Geodynamics, 5(1): 41—46.
Zhang C, Bian S, Yi Z, et al. 2011. Refining geoid and vertical gradient of gravity anomaly ［J］. Geodesy and Geodynamics, 2(4): 1—9.

[1]	XU Zhi-ping, ZHANG Yang, YANG Li-pu, XU Shun-qiang, JIANG Lei, TANG Lin, LIN Ji-yan. STUDY ON THE DEEP STRUCTURAL CHARACTERISTIC OF MAIN ACTIVE FAULTS IN HENAN PROVINCE AND ITS ADJACENT AREAS [J]. SEISMOLOGY AND GEOLOGY, 2022, 44(6): 1521-1538.
[2]	SONG Dong-mei, WANG Hui, SHAN Xin-jian, WANG Bin, CUI Jian-yong. A NOVEL EXTRACTION METHOD OF PRE-EARTHQUAKE GRACE GRAVITY ANOMALY INFORMATION BASED ON MAXIMUM SHEAR STRAIN [J]. SEISMOLOGY AND GEOLOGY, 2022, 44(6): 1539-1556.
[3]	LIAO Gui-jin, YE Dong-hua, DENG Zhi-hui, LI Chong, TANG Guo-ying, HU Wei-ming. CHARACTERISTICS OF SEISMIC GRAVITY ANOMALY AND GROUND SUBSIDENCE GRAVITY ANOMALY [J]. SEISMOLOGY AND GEOLOGY, 2022, 44(4): 895-908.
[4]	ZHANG Guo-qing, ZHU Yi-qing, LIANG Wei-feng. THE CRUSTAL DENSITY STRUCTURES AND ISOSTATIC ADDITIONAL STRESS AROUND THE FUBIANHE FAULT ON THE EASTERN MARGIN OF TIBET PLATEAU [J]. SEISMOLOGY AND GEOLOGY, 2022, 44(3): 578-589.
[5]	LIU Dong, HAO Hong-tao, WANG Qing-hua, ZHENG Qiu-yue, HUANG Jiang-pei. GRAVITY FIELD CHANGE BEFORE THE 2021 YANGBI M_S6.4 EARTHQUAKE, YUNNAN [J]. SEISMOLOGY AND EGOLOGY, 2021, 43(5): 1157-1170.
[6]	WU Gui-ju, YU Bing-fei, HAO Hong-tao, HU Min-zhang, TAN Hong-bo. THE DEEP STRUCTURAL CHARACTERISTICS AND THE SEIS-MOGENIC STRUCTURE OF THE YANGBI EARTHQUAKE REGION AND ITS SURROUNDING AREAS [J]. SEISMOLOGY AND EGOLOGY, 2021, 43(4): 739-756.
[7]	LI Zhe-jun, YI Chong-zheng, ZHOU Dong-rui, ZHENG Hai-gang, WANG Jun, LI Jun-hui, NI Hong-yu. MULTI-SCALE DECOMPOSITION OF GRAVITY ANOMALY OF THE EASTERN DABIE OROGEN AND ITS TECTONIC IMPLICATIONS [J]. SEISMOLOGY AND GEOLOGY, 2021, 43(1): 158-176.
[8]	LI Tie-ming, XU Yun-ma, YANG Yong-lin, FENG Sheng-tao. STUDY ON DYNAMIC CHANGE OF GRAVITY FIELD IN XIANSHUIHE FAULT ZONE AND THEIR RELATION TO THE OCCURRENCE OF M_S ≥ 5.0 EARTHQUAKES [J]. SEISMOLOGY AND GEOLOGY, 2018, 40(6): 1362-1379.
[9]	GUO Peng, HAN Zhu-jun, ZHOU Ben-gang, ZHOU Qing, MAO Ze-bin. TECTONIC INDICATIONS OF OCCURRENCE OF MODERATE-TO-STRONG EARTHQUAKES IN CHAOHU-TONGLING AREA, ANHUI PROVINCE [J]. SEISMOLOGY AND GEOLOGY, 2018, 40(4): 832-849.
[10]	JIANG Lei, XU Zhi-ping, FANG Sheng-ming, YANG Li-pu, LI Yi-qing, XU Shun-qiang. DEEP STRUCTURE OF NORTHERN HENAN PROVINCE AND ADJACENT AREAS DERIVED FROM GRAVITY AND SEISMIC SOUNDING DATA IN RELATION TO DISTRIBUTION OF EARTHQUAKES [J]. SEISMOLOGY AND GEOLOGY, 2018, 40(2): 323-336.
[11]	TAN Hong-bo, SHEN Chong-yang, XUAN Song-bai, WU Gui-ju, YANG Guang-liang, WANG Jian. THE SEISMOGENIC ENVIRONMENT ANALYSIS OF LUDIAN M_S6.5 EARTHQUAKE USING GRAVITY DATA [J]. SEISMOLOGY AND GEOLOGY, 2017, 39(2): 356-373.
[12]	CHEN An-guo, ZHOU Tao-fa, WANG Jian, LIU Dong-jia, GE Can. ANALYSIS ON STRUCTURAL FEATURES:INSIGHTS FROM SATELLITE-DERIVED GRAVITY MODEL AND SEISMIC PATTERN [J]. SEISMOLOGY AND GEOLOGY, 2016, 38(3): 696-710.
[13]	SU Peng, TIAN Qin-jian, LIANG Peng, LI Wen-qiao, WANG Lin. USING DEFORMED FLUVIALTERRACES OF THE QINGYIJIANG RIVER TO STUDY THE TECTONIC ACTIVITY OF THE SOUTHERN SEGMENT OF LONGMENSHAN FAULT ZONE [J]. SEISMOLOGY AND GEOLOGY, 2016, 38(3): 523-545.
[14]	WANG Xin, ZHANG Jing-fa, FU Ping-jie, GAO Min. DEEP STRUCTURES OF YISHU FAULT ZONE DERIVED FROM GRAVITY DATA [J]. SEISMOLOGY AND GEOLOGY, 2015, 37(3): 731-747.
[15]	LI Zhe-jun, XU Ru-gang, ZHANG Wei-jing, ZHANG Yi, LI Hui, YANG Guang-liang, LONG Jian-feng. ISOSTATIC GRAVITY ANOMALY, STRUCTURAL FEATURES AND SEISMICITY OF NORTH CHINA CRATON [J]. SEISMOLOGY AND GEOLOGY, 2015, 37(2): 496-509.