We investigate the impact of un-modeled 3D structural heterogeneity on inverted W-phasesource parameters. We generate a large dataset of synthetic seismograms accounting for theEarths 3D structure for 250 earthquakes globally distributed. The W-phase algorithm is thenused to invert for earthquake CMT parameters, assuming a spherical Earth model. The im-pact of lateral heterogeneity is assessed by comparing inverted source parameters with thoseused to compute the 3D synthetics. Results show that the 3D structure mainly affects centroidlocation while the effect on the other source parameters remains small. Centroid mislocationspresent clear geographical patterns. In particular, W-phase solutions for earthquakes in SouthAmerica are on average biased 17 km to the East of the actual centroid locations. This ef-fect is significantly reduced using an azimuthally well balanced distribution of seismologicalstations. Source parameters are generally more impacted by mantle heterogeneity while thescalar moment of shallow earthquakes seems to be mainly impacted by the crustal structure.Shallow earthquakes present a variability ofMrθandMrφmoment tensor elements, result-ing both from the small amplitude and a larger uncertainty of the associated Green’s functions.

中文翻译：

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3D 地球结构对 W 相 CMT 参数的影响

我们研究了未建模的 3D 结构异质性对倒置 W 相源参数的影响。我们生成了一个大型合成地震图数据集，用于解释全球分布的 250 次地震的地球 3D 结构。假设球形地球模型，然后使用 W 相算法来反演地震 CMT 参数。通过将倒置源参数与用于计算 3D 合成的参数进行比较来评估横向异质性的影响。结果表明，3D 结构主要影响质心定位，而对其他源参数的影响仍然很小。质心错位表现出清晰的地理模式。特别是，南美洲地震的 W 相解平均偏向实际质心位置以东 17 公里。使用地震站的方位角平衡分布可以显着减少这种影响。震源参数一般更受地幔非均质性的影响，而浅地震的标量矩似乎主要受地壳结构的影响。浅地震呈现出Mrθ和Mrφ矩张量元素的可变性，这是由于相关格林的振幅小和较大的不确定性造成的。职能。