Seismic imaging is the most commonly used technique to constrain the size, geometry, and current state of active magma reservoirs in the Earth's crust. However, unequivocal detection of eruptible magma bodies (>0.5 melt fraction) have not been reported yet. In this study, using teleseismic waveform modeling applied to synthetic data, we investigate the limitations of seismic inversions on resolving idealized melt‐rich layers with thicknesses smaller than the characteristic wavelength of the teleseismic waves. We show that inverting for melt‐rich layers with thicknesses of about 0.2 km, consistent with the average thickness of erupted layers associated with voluminous caldera eruptions, yields significant underestimation of the inferred melt fractions and overestimation of the thickness of that layer. We further extend our synthetic tests to study the effect of noise, variable thickness of the input melt‐rich layer, and different time windows from the seismograms on the quality of inverted parameters (thickness and melt fraction of the melt‐rich layer). We find that (1) thicker melt‐rich layers can be better resolved, (2) longer time windows (~4–6 s) from seismograms reduce the trade‐off between melt fraction and layer thickness observed in the inversion results, and (3) noise emphasizes the melt fraction‐thickness trade‐off and leads to a bias toward thicker lower melt fraction layers retrieved from the inversions. Our synthetic study therefore supports that the lack of detection of melt‐dominated horizons from seismic inversions does not preclude their existence and can be caused by a current limit in our ability to detect them.

中文翻译：

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基于远震波形模拟的岩浆储层中富熔融透镜的可探测性

地震成像是约束地壳中活动岩浆储层的大小，几何形状和当前状态的最常用技术。但是，尚未明确地发现可爆发的岩浆体（> 0.5熔体分数）。在这项研究中，使用应用于合成数据的远震波形模型，我们研究了地震反演在解析厚度小于远震波特征波长的理想熔融富集层方面的局限性。我们发现，对厚约0.2 km的富熔体层进行反演，与与大量破火山口喷发有关的喷发层的平均厚度一致，会大大低估推断的熔体分数，并高估了该层的厚度。我们进一步扩展了综合测试，以研究噪声，输入熔融富集层的可变厚度以及地震图上不同时间窗口对反演参数质量（熔融富集层的厚度和熔融分数）的影响。我们发现（1）较厚的熔融富集层可以得到较好的解析；（2）地震图的较长时间窗（〜4–6 s）减少了反演结果中观察到的熔融分数与层厚之间的权衡，并且（ 3）噪声强调了熔体分数-厚度的权衡，并导致了从反演中获取的较厚的较低熔体分数层的偏差。因此，我们的综合研究表明，缺乏从地震反演中检测到以熔体为主的地层并不能排除其存在的可能性，这可能是由于我们检测它们的能力受到当前限制所致。