Evaluation of shallow structure of Qeshm Island by two Dimensional Rayleigh wave tomography using aftershocks of 27 Nov. 2005

Gholamzadeh, Abbas; Haydarpoor, Nasim

doi:10.22071/gsj.2018.96792.1243

Document Type : Original Research Paper

Authors

¹ Assistant professor of seismology, Physics department, Faculty of science, Hormozgan University, Bandar Abbas, Iran

² Physics Department< faculty of science, Hormozgan, ac.ir

https://doi.org/10.22071/gsj.2018.96792.1243

Abstract

The main purpose of this paper is studying sedimentary layer in the Qeshm Island. We use aftershocks of 27 Nov. 2005 Qeshm Island (Mb=6.0), to perfume 2D tomography of Rayleigh waves.
We have analyzed surface wave data for 856 aftershocks, consist 9821 waveforms. The dispersion curves are calculated in the period range between 0.1 seconds and 10 seconds, which correspond to the shallow structures of uppermost crust including sedimentary layer. Surface wave tomography has also been performed to estimate the two-dimensional group velocity maps of Rayleigh waves in the region. The isolated surface wave fundamental modes by Herman and group velocities dispersion curves obtained by it, using Yanovskaya-Ditmar linear inversion method for estimation of 2D tomography maps. Based on the ray coverage, the area divided into cells with dimension 1 Km ×1 Km. in every cell and for distinct periods the velocities were calculated. The minimum dimension of distinct heterogeneities estimated as about 3 km.
Low-velocity anomalies in tomography maps can be related to the accumulation of salt plugs and some soft sediment in the area. In periods up to 4 sec, which related to shallower depths, a distinct lineation observed that may relate to a fault. It seems that this fault has cut off the sediments. Into the deeper sediment, this fault disappeared which means the sediments were softer and unbreakable.

Keywords

20.1001.1.10237429.1397.28.110.13.3

Main Subjects

Geophysics

References

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Scientific Quarterly Journal of Geosciences

Evaluation of shallow structure of Qeshm Island by two Dimensional Rayleigh wave tomography using aftershocks of 27 Nov. 2005

References

References

Volume 28, Issue 110
December 2018
Pages 109-118

Evaluation of shallow structure of Qeshm Island by two Dimensional Rayleigh wave tomography using aftershocks of 27 Nov. 2005

References

References

Volume 28, Issue 110December 2018Pages 109-118

Volume 28, Issue 110
December 2018
Pages 109-118