Improved Observations of Deep Earthquake Ruptures Using Machine Learning
Improved Observations of Deep Earthquake Ruptures Using Machine Learning
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DOI：
10.1029/2023jb027334
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发表时间：
2023-12
期刊：
影响因子：
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通讯作者：
Q. Shi;M. Denolle
中科院分区：
文献类型：
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作者：
Q. Shi;M. Denolle
在近距离记录的中等规模地震的地震噪声升高限制了我们看到其复杂性的能力。我们开发了一种基于机器学习的算法来分离频率重叠的噪声和地震信号。多任务编码器-解码器模型是围绕在本地（例如，短距离）地震数据（Yin等人，2022，https：//doi.org/10.1093/gji/ggac290），并通过使用高质量的数据进行持续学习来修改。我们对Mw5.0+深源地震的超声波P波进行去噪处理，并使用干净的P波来估计震源特征，同时降低了这些未研究地震的不确定性。我们发现矩和持续时间的标度为M0 <$τ4，由此产生的应力降和辐射能量与震级的强标度（Δσ <$M00.21 ${\Delta }\sigma \simeq {M}_{0}^{0.21}$和ER <$M01.24 ${E}_{R}\simeq {M}_{0}^{1.24}$）。辐射效率的中位数为5%，与地壳地震相比是一个较低的值。总的来说，我们表明，深源地震破裂方向性弱，子事件少，这表明一个简单的模型的圆形裂纹与径向破裂传播是适当的。当占各自的规模与地震的大小，我们发现没有系统的深度变化的持续时间，应力降，或辐射能量在100-700公里的深度范围内。我们的研究支持了Poli和Prieto（2016，https：//doi.org/10.1002/2016jb013521）的发现，调查的地震数量增加了一倍，地震震级较低。
Elevated seismic noise for moderate‐size earthquakes recorded at teleseismic distances has limited our ability to see their complexity. We develop a machine‐learning‐based algorithm to separate noise and earthquake signals that overlap in frequency. The multi‐task encoder‐decoder model is built around a kernel pre‐trained on local (e.g., short distances) earthquake data (Yin et al., 2022, https://doi.org/10.1093/gji/ggac290) and is modified by continued learning with high‐quality teleseismic data. We denoise teleseismic P waves of deep Mw5.0+ earthquakes and use the clean P waves to estimate source characteristics with reduced uncertainties of these understudied earthquakes. We find a scaling of moment and duration to be M0 ≃ τ4, and a resulting strong scaling of stress drop and radiated energy with magnitude ( Δσ≃M00.21 ${\Delta }\sigma \simeq {M}_{0}^{0.21}$ and ER≃M01.24 ${E}_{R}\simeq {M}_{0}^{1.24}$ ). The median radiation efficiency is 5%, a low value compared to crustal earthquakes. Overall, we show that deep earthquakes have weak rupture directivity and few subevents, suggesting a simple model of a circular crack with radial rupture propagation is appropriate. When accounting for their respective scaling with earthquake size, we find no systematic depth variations of duration, stress drop, or radiated energy within the 100–700 km depth range. Our study supports the findings of Poli and Prieto (2016, https://doi.org/10.1002/2016jb013521) with a doubled amount of earthquakes investigated and with earthquakes of lower magnitudes.