Constraints on absolute S velocities beneath the Aegean Sea from surface wave analysis
Constraints on absolute S velocities beneath the Aegean Sea from surface wave analysis
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DOI：
10.1111/j.1365-246x.2005.02565.x
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发表时间：
2005-03
影响因子：
2.8
通讯作者：
E. Bourova;I. Kassaras;H. Pedersen;T. Yanovskaya;D. Hatzfeld;A. Kiratzi
中科院分区：
文献类型：
--
作者：
E. Bourova;I. Kassaras;H. Pedersen;T. Yanovskaya;D. Hatzfeld;A. Kiratzi
摘要通过表面波频散分析研究了爱琴海岩石圈的三维结构。通过阵列分析和维纳滤波处理，在爱琴海地区的12个宽带站安装的持续时间为6个月的瑞利波和洛夫波。还使用了克里特地区三个GEOFON观测站的数据。由此产生的两个站的相速度被用来确定由2-D射线层析成像方法的周期为20和100秒之间的瑞利波相速度的横向变化。利用线性化反演和基于蒙特卡罗的非线性反演相结合的方法，反演得到的相速度，计算横波速度随深度的变化。绝对S波速度被分解到大约200 km的深度。在爱琴海南部观察到3%的高速异常，这归因于希腊俯冲。在爱琴海的北方部分，在受强烈伸展运动影响的北安纳托利亚断层的延长部分，我们发现在50 - 100 km深度处的绝对S波速度较低。这支持了该地区上地幔分布变形的模型。沿沿着共同剖面的单独瑞利波和洛夫波相速度反演揭示了爱琴海北方至少150 km深度的强烈洛夫-瑞利差异，即最有可能包括软流层顶部。
SUMMARY The 3-D structure of the lithosphere beneath the Aegean Sea is investigated through surface wave dispersion analysis. Rayleigh and Love waves recorded by 12 broad-band stations installed for a duration of 6 months in the Aegean region are processed through array analysis and Wiener filtering. Data from three GEOFON stations in the area of Crete were also used. The resulting two-station phase velocities are used to determine lateral variations of Rayleigh wave phase velocities between periods of 20 and 100 s by a 2-D ray tomography method. The obtained phase velocities are inverted to calculate variation of S-wave velocity with depth using a combination of linearized inversion and a Monte Carlo based non-linear inversion. The absolute S-wave velocity is resolved to a depth of approximately 200 km. A highvelocity anomaly of 3 per cent is observed in the southern Aegean attributed to the Hellenic subduction. In the northern part of the Aegean, in the prolongation of the North Anatolian Fault which is influenced by strong extensional movements, we found low absolute S-wave velocities at 50‐100 km depth. This supports a model of a distributed deformation of the upper mantle in the area. Separate Rayleigh and Love wave phase velocity inversions along common profiles reveal a strong Love‐Rayleigh discrepancy in the northern Aegean down to at least 150 km depth, i.e. most probably including the top of the asthenosphere.