用GPS时间序列获取中国大陆微动态应变场
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摘要
基于中国大陆GPS观测在国际地球参考框架(ITRF)获得的站点位置,由三角形法通过反演逐年推算中国大陆年微动态应变场.结果显示,研究区年微动态应变场大致以南北地震带为界.西部地区存在方向大体一致的年主压应变优势分布方向,方向自西向东、由近南北向转为北东向,与近代应变场的方向一致,表明西部地区变形主要是由印度板块向北推进和西伯利亚地块相对南推形成的,且整体上仍是新构造运动的继承;东部大部分地区不存在年主应变的优势分布方向.年最大剪应变在不同地区差别很大,变化范围从4.13×10-8~7.0×10-10,总体上西部大于东部.同一区域年最大剪应变的多年变化表明,西部变化大,东部变化平缓.年面膨胀显示,研究区大部分为压缩区,且同一区域的多年变化平缓.
Based on the time series of GPS station coordinate in the international earth reference frame, we evaluate annual micro-behavior of strain field in Chinese mainland with the triangle method. The results show that the annual micro-behavior of strain field is divided into two parts by the north-south earthquake belt in the research region. The prevailing direction of the compressive principal strain field is nearly consistent in the western region. From west to east, the direction varies from NS to NE. It is in accordance with the direction of the modern compressive principal strain field. This suggests that geologic deformation in western region was mainly caused by that India tectonic plate pushes the research region northward and the Siberia plate pushes it southward relatively. It is an inheritance of new tectonic motion. The prevailing direction of the principal compressive strain field does not exist in the eastern region .The annual biggest shear strain is different greatly in every grid-cell. The values varies from 4.13×10 -8 to 7.0×10 -10. By and large the annual biggest shear strain in the western region is bigger than that in the eastern region. And so is the variation between any two consecutive annual biggest shear strains in the same grid-cell. The annual surface dilatation show that in most grid-cells of the research region the surface dilatation is in compressibility, and the variation between any two consecutive annual surface dilatation in the same grid-cell is small.
Based on the time series of GPS station coordinate in the international earth reference frame, we evaluate annual micro-behavior of strain field in Chinese mainland with the triangle method. The results show that the annual micro-behavior of strain field is divided into two parts by the north-south earthquake belt in the research region. The prevailing direction of the compressive principal strain field is nearly consistent in the western region. From west to east, the direction varies from NS to NE. It is in accordance with the direction of the modern compressive principal strain field. This suggests that geologic deformation in western region was mainly caused by that India tectonic plate pushes the research region northward and the Siberia plate pushes it southward relatively. It is an inheritance of new tectonic motion. The prevailing direction of the principal compressive strain field does not exist in the eastern region .The annual biggest shear strain is different greatly in every grid-cell. The values varies from 4.13×10 -8 to 7.0×10 -10. By and large the annual biggest shear strain in the western region is bigger than that in the eastern region. And so is the variation between any two consecutive annual biggest shear strains in the same grid-cell. The annual surface dilatation show that in most grid-cells of the research region the surface dilatation is in compressibility, and the variation between any two consecutive annual surface dilatation in the same grid-cell is small.
引文
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曾秋生,卞兆银,业成之,等.1989.板内块体的现代应力场[A].见:马杏垣主编.中国岩石圈动力学图集[C].北京:中国地图出版社,20
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顾国华,孙汉荣.1998.利用GPS地形变资料在大地坐标系中计算应变[J].地壳形变与地震,18(3):315~317
顾国华,申旭辉,王敏,等.2001.中国大陆现今地壳水平运动基本特征[J].地震学报,23(4):362~369
蒋溥,戴丽思.1989.震源断错和地震应力场[A].见:马杏垣主编.中国岩石圈动力学图集[C].北京:中国地图出版社,19
敬少群,吴云,乔学军,等.2005.GPS时间序列及其对昆仑山口8.1级地震的响应[J].地震学报,27(4):394~401
李延兴,杨国华,李智,等.2003.中国大陆活动地块的运动与应变状态[J].中国科学(D辑),33(增刊):65~81
马宗晋,杜品仁.1995.现今地壳运动问题[M].北京:地质出版社,1~2
牛之俊,马宗晋,陈鑫连,等.2002.中国地壳运动观测网络[J].大地测量与地球动力学.22(3):88~94
石耀霖.2004.地应力主应力的方位角求和与平均[J].地震学报,26(1):106~109
伍吉仓,邓康伟,陈永奇.2003.三角形形状因子对地壳形变计算精度的影响[J].大地测量与地球动力学,23(3):26~30
杨少敏,王琪,游新兆.2005.中国现今地壳运动GPS速度场的连续变形分析[J].地震学报,27(2):128~138
曾秋生,卞兆银,业成之,等.1989.板内块体的现代应力场[A].见:马杏垣主编.中国岩石圈动力学图集[C].北京:中国地图出版社,20
中国地震局.2001.中国昆仑山口西8.1级地震图集[M].北京:地震出版社,1~13
周硕愚.1994.努力创建地震预报的应用基础科学兼论板内现今地壳运动动力学[J].地震学刊,1(4):12~14
周硕愚.1999.走向21世纪的地壳形变学对大陆动力学与地震预报的新推动[J].地壳形变与地震,19(1):8~12
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