In most shallow-seismic applications of full-waveform inversion, the subsurface is assumed to be isotropic, although near-surface materials may exhibit strong seismic anisotropy. Ignoring anisotropy will lead to inexact solutions when simulating wave propagation or imaging the subsurface using full-waveform inversion. For shallow structures, vertically transversely isotropic media provide a suitable approximation due to the fine horizontal layering of the sediments. We investigate the effects of anisotropy on surface waves and on shallow-seismic full-waveform inversion in vertically transversely isotropic media. The comparisons of seismograms calculated in isotropic and vertically transversely isotropic models show that the sensitivity of full-waveform inversion towards anisotropy is significantly higher for Love waves than for Rayleigh waves. This observation indicates that it is more promising to perform full-waveform inversion on Love waves rather than on Rayleigh waves to identify anisotropy of near-surface materials. Therefore, we performed synthetic twodimensional reconstruction tests of anisotropic full-waveform inversion using only shallow-seismic Love waves. These tests revealed that the parameters describing vertical transverse isotropy can be accurately reconstructed by full-waveform inversion. Although the inversion for density is still problematic, this does not affect the results for the seismic velocities in a significant way. The tests on synthetic data thus prove the general applicability and the benefits of an anisotropic inversion of shallow-seismic Love waves, which can provide a more comprehensive subsurface characterization in shallow anisotropic media.

中文翻译：

---

浅层垂直横向各向同性介质中爱波的二维弹性全波形反演：合成重建测试

在全波形反演的大多数浅层地震应用中，假设地下是各向同性的，尽管近地表材料可能表现出强烈的地震各向异性。在模拟波传播或使用全波形反演对地下成像时，忽略各向异性将导致解不精确。对于浅层结构，由于沉积物的精细水平分层，垂直横向各向同性介质提供了合适的近似值。我们研究了各向异性对表面波和垂直横向各向同性介质中浅层地震全波形反演的影响。各向同性和垂直横向各向同性模型计算的地震图的比较表明，全波形反演对各向异性的敏感性对于洛夫波明显高于瑞利波。这一观察结果表明，对洛夫波进行全波形反演比对瑞利波进行全波形反演更有希望识别近地表材料的各向异性。因此，我们仅使用浅地震 Love 波对各向异性全波形反演进行了合成二维重建测试。这些测试表明，通过全波形反演可以准确地重建描述垂直横向各向同性的参数。尽管密度反演仍然存在问题，但这并不会显着影响地震速度的结果。因此，对合成数据的测试证明了浅层地震洛夫波各向异性反演的普遍适用性和好处，可以在浅层各向异性介质中提供更全面的地下特征。