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首页> 外文期刊>Geophysical Research Letters >Lithospheric velocity structure of the New Madrid Seismic Zone: A joint teleseismic and local P tomographic study
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Lithospheric velocity structure of the New Madrid Seismic Zone: A joint teleseismic and local P tomographic study

机译:新马德里地震带的岩石圈速度结构:远震与局部层析成像联合研究

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摘要

The enigmatic seismicity in the New Madrid Seismic Zone (NMSZ) has been attributed to some abnormal lithospheric structure, including the presence of dense mafic intrusions and a low-viscosity lower crust.However, the area's detailed lithospheric structure remains unclear. Here we invert 2,056 teleseismic P and 12,226 local P first arrival times from a recent nine-year dataset to infer the lithospheric velocity structure beneath the NMSZ. Our results show that the seismically active zone is associated with a local, NE—SW trending low-velocity anomaly in the lower crust and upper mantle, instead of high-velocity intrusive bodies proposed in previous studies. The lowvelocity anomaly is on the edge of a high-velocity lithospheric block, consistent with the notion of stress concentration near theological boundaries. This lithospheric weak zone may shift stress to the upper crust when loaded, thus leading to repeated shallow earthquakes.
机译:新马德里地震带(NMSZ)的神秘地震活动归因于某些异常的岩石圈结构,包括致密的镁铁质侵入体和低粘度的下地壳,但该地区的详细岩石圈结构仍不清楚。在这里,我们从最近的一个9年数据集中反转了2,056个远震P和12,226个本地P的首次到达时间,以推断NMSZ下方的岩石圈速度结构。我们的结果表明,地震活动带与下地壳和上地幔的局部NE-SW趋势低速异常有关,而不是先前研究中提出的高速侵入体。低速异常位于高速岩石圈块的边缘,与神学边界附近的应力集中的概念一致。在加载时,该岩石圈薄弱带可能会将应力转移到上地壳,从而导致反复的浅层地震。

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