Study on medium heterogeneity beneath island arcs based on the analysis of seismic wave scattering

基于地震波散射分析的岛弧下介质非均质性研究

基本信息

批准号：
17540389
负责人：
SATO Haruo
金额：
$ 2.3万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2005
资助国家：
日本
起止时间：
2005 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-17540389/
关键词：
Seismic wave solid earth crust mantle heterogeneous structure scattering coda waves island arc 島弧

项目摘要

Source duration times of microearthquakes are short; however, apparent duration times of S wave envelopes increase with travel distance increasing caused by scattering due to medium inhomogeneities. We clarified that the medium inhomogeneity is stronger in the back-arc side of the volcanic front compared with that in the fore-arc side in Japan arc. In this research, extending this idea, we carefully measured the relation between the S-wave peak delay from the onset and the ray path. We also developed the envelope synthesis in random elastic media as the mathematical foundation for these analyses. We find that the peak delays are larger for ray paths traveling beneath Quaternary volcanoes than those for ray paths traveling between Quaternary volcanoes in northern Japan. That is, the medium inhomogeneity is stronger beneath Quaternary volcanoes, but the medium is homogeneous between them. Interpreting the partition of energy of teleseismic P and P coda waves into the transverse component as a measure of medium heterogeneity, we classified the lithospheric heterogeneity in the world : the medium heterogeneity is large at plate collision, zones and subduction zones; however, it is small in continents. On the basis of the Markov approximation we have developed the direct envelope synthesis of vector waves in random elastic media. We have successfully formulated the envelope syntheses for both the incidence of a plane wavelet and the radiation from a point source in 2-D and 3-D cases. Especially in 2-D, we have confirmed the validity by using the finite difference simulations.

微观的源持续时间很短；但是，S波信封的明显持续时间随着中等不均匀性引起的散射而增加。我们澄清说，与日本的前弧侧相比，火山阵线的背面侧面的培养基不均匀性更强。在这项研究中，扩展了这个想法，我们仔细测量了S波峰值延迟与射线路径之间的关系。我们还开发了随机弹性介质中的包膜合成，作为这些分析的数学基础。我们发现，在第四纪火山下行驶的射线路径的峰值延迟要大于在日本北部的第四纪火山之间行驶的射线路径。也就是说，在第四纪火山下，培养基不均匀性更强，但介质之间是均匀的。将伸缩症P和P尾波的能量分配到横向成分中作为中等异质性的量度，我们对世界上的岩石圈异质性进行了分类：中等异质性在板碰撞，区域，区域和俯冲区域很大。但是，它在大陆很小。根据马尔可夫近似，我们开发了随机弹性介质中矢量波的直接包膜合成。我们已经成功地制定了平面小波的发生率的包络合成，又在2-D和3-D病例中从点源中辐射。特别是在2-D中，我们通过使用有限差模拟来确认有效性。

项目成果

期刊论文数量（41）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Temporal changes in seismic velocity of the crust around Iwate volcano, Japan, as inferred from analyses of repeated active seismic experiment data from 1998 to 2003

1998—2003年重复主动地震实验数据分析日本岩手火山周边地壳地震速度随时间变化

DOI：
发表时间：
2005
期刊：
Earth Planets Space 57
影响因子：
0
作者：
Nishimura;T.;S.Tanaka;T.Yamawakil;H.Yamamoto;T.Sano;M.Sato;H.Nakahara;N.Uchidal.;S.Hori;H.Sato
通讯作者：
H.Sato

Spatial variation of lithospheric heterogeneity on the globe as revealed from transverse amplitudes of short-period teleseismic P-waves