Averbuch Gil, Waxler Roger M, Smets Pieter S M, Evers Läslo G
Department of Geoscience and Engineering, Faculty of Civil Engineering and Geosciences, Delft University of Technology, 1 Stevinweg Street, Delft, The Netherlands.
NCPA, University of Mississippi, Oxford, Mississippi, USA.
J Acoust Soc Am. 2020 Feb;147(2):1066. doi: 10.1121/10.0000695.
In seismology, the depth of a near-surface source is hard to estimate in the absence of local stations. The depth-yield trade-off leads to significant uncertainties in the source's depth and strength estimations. Long-range infrasound propagation from an underwater or underground source is very sensitive to variations in the source's depth and strength. This characteristic is employed in an infrasound based inversion for the submerged source parameters. First, a Bayesian inversion scheme is tested under the variations of the number of stations, the signal's frequency band, and the signal-to-noise ratio (SNR). Second, an ensemble of realistic perturbed atmospheric profiles is used to investigate the effect of atmospheric uncertainties on the inversion results. Results show that long-range infrasound signals can be used to estimate the depth and strength of an underwater source. Using a broadband signal proved to be a fundamental element to obtain the real source parameters, whereas the SNR was secondary. Multiple station inversions perform better than one-station inversions; however, variations in their position can lead to source strength estimations with uncertainties up to 50%. Regardless of the number of stations, their positions, and SNRs, all of the estimated depths were within 10% from the real source depth.
在地震学中，若没有本地台站，近地表震源的深度很难估算。深度与产额的权衡导致震源深度和强度估算存在显著不确定性。来自水下或地下震源的远程次声传播对震源深度和强度的变化非常敏感。基于次声的水下震源参数反演利用了这一特性。首先，在台站数量、信号频段和信噪比（SNR）变化的情况下，对贝叶斯反演方案进行了测试。其次，使用一组实际的扰动大气剖面来研究大气不确定性对反演结果的影响。结果表明，远程次声信号可用于估算水下震源的深度和强度。事实证明，使用宽带信号是获取真实震源参数的基本要素，而信噪比则是次要的。多台站反演比单台站反演效果更好；然而，台站位置的变化会导致震源强度估算的不确定性高达50%。无论台站数量、位置和信噪比如何，所有估算深度与真实震源深度的偏差均在10%以内。
