Mw6.6级芦山地震三要素的准实时反演

Quasi-real time determination of 2013Mw 6.6Lushan Earthquake Epicenter,Trigger Time And Magnitude Using 50Hz GPS Observations

利用50Hz,芦山地震前后3min的超高频全球定位系统观测数据,解算分析地震周边8个连续运行参考站的水平运动特征,通过S变换分析地震波的震相,拾取地震波到达测站的时刻,并利用地震波到达测站的时间差和测站的坐标反演震中位置与发震时刻。结果发现:距离震源较近的QLAI、SCTQ和YAAN测站受地震影响最大,水平方向的最大摆幅在50mm左右,QLAI站在E方向的瞬时速度最大时达到72.36mm/s,E方向的瞬时加速度最大时达到105.9mm/s2,地震对其他测站影响相对较小。仅利用地震波最先到达的三个测站,可快速反演出震中位置为30.04°N,103.05°E,与中国地震局,美国地质调查局公布的结果基本一致,震级可利用经验回归方法,通过水平位移峰值反演。研究表明GPS超高频数据不仅能详致地反映震时地表的运动过程,还可快速准确反演出强内陆地震的三要素。

50Hz global positioning system（GPS）high rates data of 8continual operation reference system（CORS）sites nearby Lushan are used to analyze the earthquake trigger time,epicenter and magnitude.All sites position time series on N,E directions are resolved with the track software,and horizontal accurancy can reach to 2cm at least.Horizontal position time series analyses show that the earthquake mainly affects QLAI,SCTQ,YAAN sites,the horizontal peak amplitudes can reach to50 mm,the maximum instantaneous velocity can reach to 72.36 mm/s and the maximum instantaneous acceleration have reached to 105.9mm/s2.Analyzing the position time series by the method of S transformation,the arrival time of seismic wave is estimated.With seismic wave arriving time and coordinates of three sites which are first detecting the seismic wave,the earthquake＇s epicenter and trigger time can be fast determined by three-dimensional search method.Moreover,the earthquake magnitude can also be estimated by horizontal peak amplitudes from the sites using the regression method.These suggest exiting GPS infrastructure could be developed into an effective component of earthquake assessment.