Crustal anisotropy along the Sunda-Banda arc transition zone from shear wave splitting measurements

详细信息    查看全文

• 作者：Syuhada Syuhada^a ; ^b ; ^{syuhada@lipi.go.id} ; ^{hadda9@gmail.com} ; Nugroho D. Hananto^c ; Chalid I. Abdullah^d ; Nanang T. Puspito^e ; Titi Anggono^a ; Tedi Yudistira^e ; Mohamad Ramdhan^f
• 关键词：Sunda-Banda arc transition zone ; Shear wave splitting ; Crustal anisotropy
• 刊名：Journal of Geodynamics
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：103
• 期：Complete
• 页码：1-11
• 全文大小：3345 K
• 卷排序：103

文摘

We analyse shear wave splitting derived from the local earthquakes recorded at 13 seismic stations to investigate crustal anisotropy over varied geological regimes of the Sunda-Banda arc transition zone. We determine high-quality splitting measurements for 262 event-station pairs. The orientations of fast polarisation for the stations located in the oceanic regime are generally parallel or sub-parallel to the directions of the principal compressional strain-rate axes with a lack of dependency of delay time δt on increasing depth. The results suggest that anisotropy in this domain is primarily due to the influence of stress induced anisotropy on the upper crust. On the other hand, the average fast polarisations show more scattered for the stations located around Sumba Island and in the collision regime, implying a mix of anisotropy causes. Thus, anisotropy in this region is not only controlled by preferentially aligned cracks due to tectonic stress, but also by preferential mineral alignment and macro-scale faults associated with the regional tectonic deformation. We also perform further analysis to search possible temporal variations of splitting parameters associated with the stress changes excited by large earthquakes. The association between variation in splitting parameters and earthquake activity observed in this study might provide useful information about accumulation of stress before large events, and thus might be considered as an earthquake-forecasting tool in the future.