Enhanced Resolution of the Subducting Plate Interface in Central Alaska From Autocorrelation of Local Earthquake Coda
Enhanced Resolution of the Subducting Plate Interface in Central Alaska From Autocorrelation of Local Earthquake Coda
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DOI：
10.1029/2018jb016167
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发表时间：
2019-02
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影响因子：
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通讯作者：
Doyeon Kim;K. Keranen;G. Abers;L. Brown
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作者：
Doyeon Kim;K. Keranen;G. Abers;L. Brown
深度低于10 km的俯冲板块主要使用频率主要低于1 Hz的俯冲地震的相位成像，导致与断层带厚度相比分辨率较低的图像。在这里，我们使用当地地震尾波中的散射体波到达对阿拉斯加的板块边界区进行成像，以生成板的更高分辨率图像。自相关方法成功地从近震信号中提取了相干波至。我们的自相关结果图像接口与俯冲大洋板块在更高的分辨率比我们的Escherichia接收器功能，增加的连贯性和更清晰的边界。我们的研究结果提供了第一个相干结构图像的孕震区使用散射的本地体波。振幅表明，地震波速度随着低速带内深度的增加而降低，支持我们地区的岩性模型而不是纯粹的超压模型。使用密集台站的类似方法可以提供更高分辨率的图像，以表征全球地壳和上地幔边界。
Subducting plates below 10‐km depth are primarily imaged using phases from teleseismic earthquakes at frequencies dominantly below 1 Hz, resulting in low‐resolution images compared to fault zone thickness. Here we image the plate boundary zone in Alaska using scattered body wave arrivals in local earthquake coda to produce a higher‐resolution image of the slab. An autocorrelation method successfully extracts coherent arrivals from the local earthquake signals. Our autocorrelation results image interfaces associated with the subducting oceanic plate at higher resolution than our teleseismic receiver functions, with increased coherence and sharper boundaries. Our results provide one of the first coherent structural images of the seismogenic zone using scattered local body waves. Amplitudes suggest that seismic wave speed decreases with increasing depth within the low‐velocity zone, supporting lithologic rather than purely overpressure models for the zone in our region. Similar methodologies using dense stations could provide higher‐resolution images to characterize crustal and uppermost mantle boundaries globally.