高频GPS形变波与地震波在日本M_W9.0地震中的对比研究

Comparison between High Frequency GPS Deformation Wave and Seismic Wave of Japan Great Earthquake

高频GPS动态监测可快速准实时解算地表位移,其在地震参数快速确定、地壳形变短期变化过程、震源破裂过程和震级标度研究等方面成为传统地震学的补充。针对浙江省内的1Hz的GPS数据,本文采用GAMIT的TRACK模块,获得了日本2011年3月11日M_W9.0地震的位移时间序列,并将其与浙江省地震台网并址观测的地震计获得的位移信号进行对比。结果显示,高频GPS与地震计获得的峰值地动位移之间差异在GPS的观测误差范围内。相对于原始波形,两者在0.005~0.1Hz频段上的水平方向相关系数提高了50%以上,高程方向相关系数提高了2倍以上。研究表明,高频GPS与宽频带地震计的观测结果在时序和频谱上有相互重合的区域,GPS和地震仪可以共同覆盖地震地表位移的全部可能范围。

High frequency GPS dynamic monitoring is capable of quickly calculating the surface displacement in quasi real time,which is helpful in supplement to the traditional seismology in the aspects of rapid determination of seismic parameters,short-term variation process of crustal deformation,focal rupture process and magnitude scaling.Based on the 1 Hz GPS data in Zhejiang Province,we obtained the displacement time series of the M_W9.0 earthquake in Japan on March11,2011 by using the track module of GAMIT.Then we compared the displacement signals obtained by the seismometers observed by the seismic network of Zhejiang Province with that from the displacement time series of GPS data.The results show that the difference between the peak ground motion displacement obtained by high frequency GPS and seismometer is within the range of GPS observation error.In the frequency range of 0.005~0.1 Hz,the correlation coefficient of the two waveforms in horizontal direction is increased by more than 50%,and that in elevation direction is increased by more than 2 times.The results suggest that the observation of high frequency GPS and broadband seismometer overlaps each other in time sequence and frequency spectrum,and GPS and seismograph can cover the whole possible range of earthquake surface displacement.