基于DInSAR和MAI技术揭示地震三维形变场

Mapping three-dimensional co-seismic deformation by combining multipleaperture interferometry and differential interferometric synthetic aperture radar

针对DInSAR技术只能获得雷达视线方向形变,无法完全反映地震三维形变场的缺点,提出了利用升降轨SAR干涉对,联合DInSAR技术和MAI技术,采用抗差最小二乘方法求解三维地表形变场,采用残差绝对值和最小法确定权矩阵,保证了结果的可靠性.以2003年伊朗BAM地震为例,分析结果表明:BAM地震运动方式不仅具有南北向的水平走滑,而且带有较大的垂直分量和东西向水平分量.MAI技术形变监测受相干值影响,在相干值大于0.6的区域相位标准差小于0.075m.三维形变场在上下和东西方向分量和联合DInSAR和Offset Tracking技术结果一致,在相干值大于0.6时,最大差异为0.031m;南北方向分量差异较大,达到dm级.提出方法更好地重建地震三维形变场,有助于更好地分析地震发生的原因和影响范围.

One of the limitations of DInSAR is that this technique is only sensitive to the displacements along the radar line-of-sight（LOS）direction,which is impossible to determine3-D co-seismic deformation.To retrieve the 3-D co-seismic deformation,a method based on the robust least squares method that combines multiple-aperture interferometry（MAI）and differential interferometric synthetic aperture radar（DInSAR）was applied to one ascending and one descending interferometric pair,and successfully applied to the BAM（Iran）earthquake event in 2003.The results show that coseismic deformation not only has the level strike-slip in northsouth direction,but also has a large vertical component and a horizontal component in east-west direction.MAI was affected by interferogram coherence.In areas with high coherence（0.6）,measurement standard deviation is less than 0.075 m.In areas with coherence（0.6）,the 3-D deformation was consistent with the result of combining MAI and Offset Tracking technology in up-down and east-west direction,the maximum difference between them was 0.031 m.But the difference in south-north direction was larger,achieved dm.A3-D deformation reconstruction through the proposed method will allow for better modeling,and hence,a more comprehensive understanding,of the source geometry associated with seismic.