Spatial variations of the 660-km discontinuity in the western Pacific subduction zones observed from CEArray triplication data
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- 作者：Baoshan Wang (1)
Fenglin Niu (2) - 关键词：P ; wave triplication ; 660 ; km discontinuity ; western Pacific subduction zone ; P315.2
- 刊名：Earthquake Science
- 出版年：2011
- 出版时间：February 2011
- 年：2011
- 卷：24
- 期：1
- 页码：77-85
- 全文大小：1198KB
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Fenglin Niu (2)
1. Institute of Geophysics, China Earthquake Administration, Beijing, 100081, China
2. Department of Earth Science, Rice University, Houston, TX, 77005, USA - ISSN：1867-8777
文摘
We examined the spatial variation of velocity structures around the 660-km discontinuity at the western Pacific subduction zones by waveform modeling of triplication data. Data from two deep earthquakes beneath Izu-Bonin and Northeast China are used. Both events were well recorded by a dense broadband seismic network in China (CEArray). The two events are located at approximately the same distance to the CEArray, yet significant differences are observed in their records: (1) the direct arrivals traveling above the 660-km discontinuity (AB branch) are seen in a different distance extent: ?9° for the NE China event, ?3° for Izu-Bonin event; (2) the direct (AB) and the refracted waves at the 660-km (CD branch) cross over at 19.5° and 17° for the NE China and the Izu-Bonin event, respectively. The best fitting model for the NE China event has a broad 660-km discontinuity and a constant high velocity layer upon it; while the Izu-Bonin model differs from the standard IASP91 model only with a high velocity layer above the 660-km discontinuity. Variations in velocity models can be roughly explained by subduction geometry.