Implications of seismic waveforms: Complex physical properties associated with stagnant slab
Implications of seismic waveforms: Complex physical properties associated with stagnant slab
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DOI：
10.1029/2005gl024314
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发表时间：
2004-12
影响因子：
5.2
通讯作者：
F. Tajima;T. Nakagawa
中科院分区：
文献类型：
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作者：
F. Tajima;T. Nakagawa
在对扁平高速区采样后，在一些区域台站观察到深源事件的P波异常增宽。这些地震的震源过程都很短，其它台站的P波和相应的SH波没有这种异常。对于过渡区中的扁平冷板，其波形可以用相对简单的模型M3.11或M2.0合成。我们认为，P波展宽是由SV转换波在“660 km”不连续面或板片边界附近的狭窄区域内的非均匀性引起的。这种非均匀性的产生可能与水相变的复杂结构和与停滞板相关的冷温度异常有关。
Anomalously broadened P waveforms of deep focus events were observed at some regional stations after sampling flattened high velocity zones. The source processes of these events are short and the P waveforms at other stations as well as the corresponding SH waves do not show such anomaly. The rays of the anomalous waves propagated in the vicinity of those whose waveforms can be synthesized with a relatively simple model M3.11 or M2.0 for a flattened cold slab in the transition zone. We suggest that the P waveform broadening is caused by SV converted waves at the heterogeneities within a narrow zone near the “660 km” discontinuity or slab boundary. The creation of such heterogeneities may involve in the complex structure of phase transformation with water and cold temperature anomaly associated with stagnant slab.