Constructing a 3‐D Radially Anisotropic Crustal Velocity Model for Oklahoma Using Full Waveform Inversion
Constructing a 3‐D Radially Anisotropic Crustal Velocity Model for Oklahoma Using Full Waveform Inversion
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DOI：
10.1029/2023jb026992
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发表时间：
2023-11
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影响因子：
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通讯作者：
Shuo Zhang;Hejun Zhu
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作者：
Shuo Zhang;Hejun Zhu
在过去的十年里，俄克拉荷马州的地震活跃率显著增加，这与注入盐水和水力压裂等工业作业有关。利用诱发地震和新近部署的地震仪，利用全波形反演法建立了俄克拉荷马州地壳三维径向各向异性地震速度模型。为了缓解众所周知的周期跳跃问题，我们使用了基于几个频带上的相位和波形差异的失配函数。通过反演模型中的相对速度扰动，我们可以圈定俄克拉荷马州的主要地质省，如阿纳达科盆地和切诺基地台/陆架。此外，倒置模型中的径向各向异性反映了俄克拉荷马州地壳内部的变形，这可能与沉积分层、微裂缝/裂缝以及各向异性矿物的优势取向有关。从新的速度模型可以推断出俄克拉荷马州的结晶基底，这使我们能够更好地对当前地震目录中的诱发地震活动进行分类。此外，综合实验表明，新的速度模型使我们能够更好地约束俄克拉荷马州的地震位置，特别是确定它们的深度，这对于研究诱发地震活动是重要的。
Over the past decade, the seismicity rate in the state of Oklahoma has increased significantly, which has been linked to industrial operations, such as saltwater injection and hydraulic fracturing. Taking advantage of induced earthquakes and recently deployed seismometers, we construct a 3‐D radially anisotropic seismic velocity model for the crust of Oklahoma by using full waveform inversion. To mitigate the well‐known cycle‐skipping problem, we use misfit functions based on phase and waveform differences in several frequency bands. Relative velocity perturbations in the inverted model allow us to delineate major geological provinces in Oklahoma, such as the Anadarko Basin and the Cherokee Platform/Shelf. In addition, radial anisotropy in the inverted model reflects deformation within the crust of Oklahoma, which might correlate with sedimentary layering, microcracks/fractures, as well as dominant orientation of anisotropic minerals. The crystalline basement beneath Oklahoma can be inferred from the new velocity model, which enables us to better classify induced seismicity in current earthquake catalogs. Furthermore, synthetic experiments suggest that the new velocity model enables us to better constrain earthquake locations in Oklahoma, especially for determining their depths, which are important for investigating induced seismicity.