利用三重震相探测中国东部海域410 km深度低速层
Low-velocity anomaly around 410 km beneath the Yellow and East China Seas with P wave triplications
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摘要: 基于中国数字地震台网记录的日本本州地区2009年发生的一次震源深度为167.2 km、 震级为mb6.0地震的宽频带波形资料，利用二维射线追踪方法给出P波三重震相的理论时距曲线，并采用试错法构建出与观测时距曲线拟合效果最优的低速异常模型，发现在中国东部海域下方410 km间断面上、下均存在局部的P波低速异常：300—410 km深度范围内低速异常为4%—5%，而410—460/470 km深度范围内的低速异常则达到4%—7%．结合前人地震层析成像结果，发现该区域不存在明确外源热流，因而，本文认为该低速异常与俯冲板片脱水引起的部分熔融有关．Abstract: Broadband waveform data for one mb6.0 earthquake beneath Honshu,Japan, with focal depth of 167.2 km, recorded by China Digital Seismic Network (CDSN) were retrieved. Through trial-and-error method, the anomalous models beneath the Yellow and East China Seas for the six sub-regions were obtained by matching the theoretical travel-time curves of the P triplications from the modified models for the six sub-regions by using 2-D ray tracing with the observed ones. The local lower velocity anomaly appears around the 410 km discontinuity. Above the discontinuity, the P wave velocity decreases by 4%—5% from 300 km to 410 km and below the discontinuty, the velocity decreases by 4%—7% from 410 km to 460/470 km. Because thermal flow was not observed by former seismic tomographic results, the local low velocity anomaly should be due to the partial-melting caused by the dehydrated water from subducting slab.
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期刊类型引用(5)
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百度学术
2. 李国辉，白玲，周元泽，崔清辉. 地幔过渡带顶部低速层地震学研究进展. 地球物理学进展. 2018(04): 1366-1373 . 百度学术
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其他类型引用(7)
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