短周期地震仪接收函数的可行性分析——以新疆和田地震台阵为例

利用新疆和田地震台阵3 km孔径范围内架设的9个子台(包括1套宽频带和9套短周期地震仪)记录的3年远震波形数据,对比研究和分析了短周期地震仪接收函数的稳定性和可靠性.通过比较和分析短周期和长周期地震仪获取的接收函数波形,结果发现:(1)短周期地震仪记录与宽频带地震仪记录得到的接收函数有很好的一致性,且具有较高的稳定性,无论α取值为1.5还是2.5,短周期地震仪接收函数与宽频带地震仪接收函数都具有较强的线性相关性(相关系数0.9),但Ps震相均存在小幅的振幅差(约20%);(2)采用接收函数震相到时信息的方法(如H-κ叠加搜索),短周期地震仪可以代替宽频带地震仪;(3)由于短周期地震仪缺乏0.155 Hz以下的低频信号和在1 Hz以下频段非线性的振幅响应,仅仅采用短周期地震仪接收函数波形反演台站下方S波速度结构,获得下地壳到上地幔顶部的速度偏差较大(约0.3 km/s),可能会造成错误解释(如下地壳低速层),因此需要和其它对波速值敏感的数据(如面波频散)进行联合分析.

Feasibility analysis of short-period seismograph receiver function——An example of Hotan Seismic Array, Xinjiang

Using the teleseismic waveform data recorded by 9 sub-stations (including 1 set of broadband and 9 sets of short-period seismographs) of Hotan Seismic Array with an aperture about 3 km in 3 years, we studied and analysed the stability and reliability of short-period seismograph receiver function. By comparative analysis of the receiver function waveforms isolated from teleseismic waveform data recorded by short-period and broadband seismographs, the following results are obtained. (1) Receiver functions of short-period and broadband seismographs are very consistent and highly stable, they have good linear correlation (correlation coefficient 0.9), but Ps seismic phases have small amplitude difference (about 20%), whenever the Gaussian coefficient value is 1.5 or 2.5. (2) The short-period seismograph receiver functions can replace broadband seismograph receiver functions, if a method using the seismic phase arrival time of receiver functions is adopted (such as grid-stacking-search method). (3) The result may cause wrong interpretation (e.g., the lower crust low-velocity layer) if only the waveform data of short-period seismograph receiver functions are used to invert for crustal S-wave velocity structure, because there exist large velocity deviations (about 0.3 km/s) from lower crust to upper mantle, due to lack of low frequency information under 0.155 Hz and the nonlinear amplitude response under 1 Hz of the short-period seismographs; so additional data sensitive to wave velocity value (such as surface wave dispersion) are needed for joint analysis.