利用连续GPS资料分析芦山7.0级地震区域地壳变形特征
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摘要
2013年4月20日,龙门山断裂带南段四川芦山附近发生7.0级地震,造成较严重地震灾害及其次生灾害。为研究地震区域地壳变形特征,利用芦山地震震中周边陆态网GPS连续站2010-2013年的观测资料,得到发震区域水平运动速度场和垂直形变场,获得距震中较近站点的同震位移;利用站间基线时间序列和应变参数时间序列得到了区域应变积累背景,并结合块体运动信息分离方法,进一步分析了震前可能存在的异常形变信息。从中得知:芦山地震发震区域处于块体挤出的"分流"地带,地壳水平变形量较小。站间基线QHBM-SCSN和QHBM-SCXJ在2012年下半年均出现偏离原有运动速率的趋势。SCXJ站时间序列信息分离结果显示,其N向和E向应变贡献分量在2012年也有曲线转折现象。
In April 20 th,2013,an earthquake attacked the region of Lushan,Sichuan province in the southern Longmen mountains fault zone,and caused serious earthquake disaster and secondary hazards. In order to research the seismic crustal deformation characteristics,GPS continuous data in 2010- 2013 from the CMONOC around the epicenter of Lushan earthquake is used,the regional horizontal velocity and vertical deformation are calculated,and the coseismic displacement of the station near the epicenter is obtained. Based on the station baselines and strain parameter time series,the regional crustal deformation and strain accumulation background are researched; further analysis with the block information separation method shown that the abnormal deformation may exist before the earthquake. The main results got in this paper include: the earthquake region is in the block extrusion "shunt"zone,and the crustal horizontal movement is small. In the second half of 2012,a trend of deviation from the original motion was shown by the baseline of QHBM-SCSN and QHBM-SCXJ. Results of deformation separated from the time series of SCXJ station also showed that,the N and E component of the internal strain contribution had a curve-transition phenomenon.
引文
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