Moho Depth and Crustal Vp/Vs Ratio in the Northern Slopes of the Binalud Mountains, Mashhad Plain, Inferred From Receiver Functions of Teleseismic Events Observed by the Khorasan Seismic Network

Document Type : مقالات پژوهشی

Authors

• Hossein sadeghi
• Bahram Nasiripour ¹
• Ayoub Kaviani ²
• Hiroshi Takenaka ³

¹ Earthquake Research Center, Ferdowsi University of Mashhad, Iran

² Physics Department,Institute for Advanced Studies in Basic Sciences, Zanjan,Iran

³ Department of Earth and Planetary Sciences, Kyushu University, Japan

10.22067/sed.facies.v1i1.724

Abstract

The Khorasan Region is one of the active seismic zones in Iranian plateau, which is located between central Iran and Kopet-Dagh zones. We study the crustal thickness (H) and Vp/Vs ratio (k) in Mashhad, capital of Razavi Khorasan province by the receiver function method. This study uses teleseismic events recorded by an array of three broadband stations of Khorasan Seismic Network, Earthquake Research Center, Ferdowsi University of Mashhad. In the radial receiver function, the first phase following the direct P-wave, with relatively larger amplitude, is the Moho P to S conversion (Ps). Therefore by picking up arrival time of P to S conversion on the radial receiver function and from time to depth relation for this phase, the crustal thickness under each station can be estimated using a reference earth velocity model. Here the IASPEI91 velocity model is used. In order to process a large amount of teleseismic events, to reduce the effect of lateral structural variations, to calculate the variance of H and k, and the lack of need for picking arrival times of P to S conversions, we use the Zhu and Kanamori's stacking algorithm (Zhu and Kanamori, 2000). Based on the results of this method, the crustal thickness in the study area is 51±3 km and the Vp/Vs ratio is 1.65±0.06 on average.

Keywords

• Receiver function
• Crustal thickness
• Vp/Vs ratio
• Mashhad

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