全球地震面波相速度变化及其大地构造学意义

从1980年到1992年间震级M≥6．0天然地震的全球数字地震台网记录，搜集约30000个长周期地震图波形数据，建立了周期为85-250s的全球Love波和Rayleish波相速度变化模型．全部地震图均通过时间域和频率域的质量控制，震相为短大圆弧和长大圆弧基频振型G1，R1，G2和R2．利用将区域高分辨率反演结果嵌入全球模型框架的混合反演参量化方法，以及地形、地貌和地壳厚度模型，得到校正前、后的两种反演结果．与已有全球相速度模型比较，长波分量的幅度和空间图像符合较好．短周期相速度异常反映了地表板块构造，与大陆地盾、大洋中脊和构造活动区相关；板块构造相关性随面波周期增大而逐渐消失；部分海洋热点与100-200s周期的低速异常相联系．

GLOBAL SURFACE WAVE PHASE VELOCITY VARIATIONS AND THEIR TECT0NIC IMPLICATIONS

Using about 30000 long period seismic waveforms, which are associated with earthquakes M≥6.0 recorded by global digital seismic networks between 1980 and 1992, global Love and Rayleigh wave phase velocity variations in periods of 85s and 250s are obtained. All of waveforms are visually inspected in time and spectral domains, and the used phases are minor and major great circle phases Gl, R1, G2,and R2. Using the hybrid parameterization, in which final block inversion in higher regional resolution is embed in an aspherical reference model, and considering of the topography and crustal thickness variation, the inversions are performed with and without shallow layer corrections. Comparing with previous global phase velocity models, the l0ng wave length features are consistent both in magnitudes and variation patterns. The short period phase velocity variations are correlated with continental craton, middle cocean ridge, and tectonic activities,The correlation,however,decreases with period increases,And some oceanic hotspots are related to slow velocity anomalies.