PSInSAR方法探测意大利拉奎拉地震形变过程分析
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摘要
采用双轨处理模式对8景ENVISAT降轨数据进行永久散射体(PS)时间序列处理,获得了2009年4月6日意大利拉奎拉(L’Aquila)Mw 6.3级地震区域的PS时序差分干涉图和形变场。结合Delaunay三角形剖分算法对破裂区的形变过程进行数值分析,结果表明:①本次地震变形最强烈、地表破裂发生的区域是一个地势相对较低的椭圆形洼地。破裂主要沿震中的东南方向传播,面积约22×14km2,方向约135°。②地震产生的形变量集中在破裂区,主要在震时及震后形成,位移场视线向下沉量达150mm。③破裂区位移场数值分析表明,本文提出的数据处理策略较完整地揭示了此次地震位移场变化的全过程,在8景雷达数据所跨时间段内,震前2008年4月与2009年2月两景资料显示,研究区位移场变化不明显,2009年2月至震后的2009年4月的图像显示,震中区形变场快速变化,沉降量达130mm;6～7月,形变场的沉降速度明显减缓,8月30日最后一景资料显示,沉降速度出现加速,破裂区总下沉量达150mm。
Using 8 descending track Envisat ASAR images,time series of different interferograms and consequent co-seismic deformation field of the L'Aquila earthquake(Mw 6.3 on 6 April 2009) were obtained by PSInSAR method.Furthermore,deformation processes of rupture zone were numerically analyzed using Delaunay triangulation algorithms based on above results.The results show that:① The rupture center located at a low elliptic depression region.The cracking propagated along southeastward direction with an orientation of 135° and covered about 22×14 km2.② The deformation area was mainly located in the rupture center,which was formed at the epoch of earthquake and thereafter.The displacement of rupture center in radar line of sight was as high as 150 mm.③ The numerical analysis results of the entire deformation process in rupture zone detected by Envisat show that: from Jan.2008 to Feb.2009 before the earthquake,the ground deformation of target zone was not significant;from Feb.to Apr.2009 after the shock,the deformation field of rupture zone changed rapidly with a maximum of subsidence of 130 mm;from Jun.to Jul.2009,the settling velocity of deformation field was slowing-down;while on 30 Aug.2009,the subsidence rate shown from last SAR image turns to accelerate,and total settlement amount in rupture zone reached 150 mm.
Using 8 descending track Envisat ASAR images,time series of different interferograms and consequent co-seismic deformation field of the L'Aquila earthquake(Mw 6.3 on 6 April 2009) were obtained by PSInSAR method.Furthermore,deformation processes of rupture zone were numerically analyzed using Delaunay triangulation algorithms based on above results.The results show that:① The rupture center located at a low elliptic depression region.The cracking propagated along southeastward direction with an orientation of 135° and covered about 22×14 km2.② The deformation area was mainly located in the rupture center,which was formed at the epoch of earthquake and thereafter.The displacement of rupture center in radar line of sight was as high as 150 mm.③ The numerical analysis results of the entire deformation process in rupture zone detected by Envisat show that: from Jan.2008 to Feb.2009 before the earthquake,the ground deformation of target zone was not significant;from Feb.to Apr.2009 after the shock,the deformation field of rupture zone changed rapidly with a maximum of subsidence of 130 mm;from Jun.to Jul.2009,the settling velocity of deformation field was slowing-down;while on 30 Aug.2009,the subsidence rate shown from last SAR image turns to accelerate,and total settlement amount in rupture zone reached 150 mm.
引文
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[13]张勇,陈运泰,许力生.2009年4月6日意大利拉奎拉(L’Aquila)Mw6.3地震的破裂过程[J].地球物理学报,2010,53(6):1 428-1439
[2]赵超英,张勤,丁晓利,等.利用InSAR技术定位西安活动地裂缝[J].武汉大学学报.信息科学版,2009,34(7):809-813
[3]许才军,林敦灵,温扬茂.利用InSAR数据的汶川地震形变场提取及分析[J].武汉大学学报.信息科学版,2010,35(10):1 138-1142
[4]孙建宝,徐锡伟,沈正康,等.基于线弹性位错模型及干涉雷达同震形变场反演1997年玛尼Mw7.5级地震参数——Ⅰ.均匀滑动反演[J].地球物理学报,2007,50(4):1097-1110
[5]单新建,宋小刚,韩宇飞,等.汶川Ms8.0地震前InSAR垂直形变场变化特征研究[J].地球物理学报,2009,52(11):2 739-2745
[6]冯万鹏,许力生,李振洪.2008年10月当雄Mw 6.3级地震断层参数的InSAR反演及其构造意义[J].地球物理学报,2010,53(5):1 134-1142
[7]张国宏,屈春燕,宋小刚,等.基于InSAR同震形变场反演汶川Mw7.9地震断层滑动分布[J].地球物理学报,2010,53(2):269-279
[8]Sousa J J,Ruiz A M.PS-InSAR Processing Methodologies in the Detection of Field Surface Deformation-Study of the Granada Basin(Central Betic Cordilleras,southern Spain)[J].Journal of Geodynamics,2010,49:181-189
[9]Ding Xiaoli,Liu Guoxiang,Li Zhiwei,et al.Ground Subsidence Monitoring in Hong Kong with Satellite SAR Interferometry[J].Photogrammetric Engineering&Remote Sensing,2004,70(10):1131-1137
[10]Colesanti C,Ferretti A,Novali F,et al.SAR Monitoring of Progressive and Seasonal Ground Deformation Using the Permanent Scatterers Technique[J].IEEE Trans on Geosci Remote Sens,2003,41(7):701-1685
[11]Hooper A,Segall P,Zebker H.Persistent Scatterer Interferometric Synthetic Aperture Radar for Crustal Deformation Analysis,with Application to Volca’n Alcedo,Gala’pagos[J].J Geophys Res,2007,112:B07407
[12]Zebker H A,Villasenor J.Decorrelation in Interferometric Radar Echoes[J].IEEE Trans on Geosci Remote Sens,1992,30(5):950-959
[13]张勇,陈运泰,许力生.2009年4月6日意大利拉奎拉(L’Aquila)Mw6.3地震的破裂过程[J].地球物理学报,2010,53(6):1 428-1439
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