Determination of the Fault Plane of the 2017 Iranian Sefidsang Earthquake, Mw 6.0, by Seismic Moment Tensor Inversion Method

Document Type : Research Article

Authors

1 Ph.D. Candidate, Seismology Department, Institute of Geophysics, University of Tehran, Tehran, Iran

2 Assistant Professor, Institute of Geophysics, University of Tehran, Tehran, Iran

3 Ph.D. Candidate, Institute of Geophysics, University of Tehran, Tehran, Iran

Abstract

Essentially, assuming a simple fault model, the hypocenter and centroid should be located on the same plane. This approximation can help to distinguish the fault plane from the auxiliary plane of an earthquake in many situations. On April 5, 2017, the Sefidsang earthquake Mw 6 occurred in north-eastern Iran. It was not possible to relate a fault to the earthquake according to the reports of the Iranian seismological center (IRSC) and the International Institute of earthquake engineering and seismology (IIEES) of Iran. The association of the earthquake to the western part of the Fariman fault or to the southern end of the Kashfroud fault is not possible. In this study, data from the stations of the aforementioned agencies was used to model the earthquake waveforms, and an effort was made to find the focal mechanism of this earthquake, investigate it, and also to eliminate the ambiguities that exist in determining the fault plane of the earthquakes using the Hypocenter-Centroid (H-C) method, due to the higher accuracy in simulating the waveforms and finding the centroid point of earthquakes in local and regional distances. we obtain the fault plane with a strike of 324 and dip of 44 degrees, which indicates the northwest-southeast trend, parallel to the trend of the Kashfroud fault. This has good agreement with the results of other researchers.

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References

Bouchon, M. (1981). A simple method to calculation green’s function for elastic layered media. Bulletin of the Seismological Society of America, 71, 959-971.
Ghayournajarkar, N., & Fukushima, Y. (2020). Determination of the dipping direction of a blind reverse fault from InSAR: case study on the 2017 Sefid Sang earthquake, north-eastern Iran. Journal of the Earth and Space Physics, 72(1), 1-15.
Hesami Azar, Kh. (2007). Seismotectonics section of the report of earthquake risk estimation studies and geotechnical earthquakes in the construction of Imam Reza Holy Shrine. International Institute of Earthquake Engineering and Seismology, Tehran, Iran.
Hesami Azar, Kh., Jamali, F., Tabassi, H. (2003). Major active faults of Iran (map). Ministry of Science, Research and Technology, International Institute of Earthquake Engineering and Seismology.
Kagan, Y.Y. (1991). 3-D rotation of double-couple earthquake sources. Geophysical Journal International, 106(3), 709–716.
Khorrami, Z., Moradi, A., & Songhori, A. (2022). The Relocation of April 5th, 2017 Sefid-Sang Earthquake aftershocks sequence using Waveform cross-correlation and double-difference techniques. Journal of the Earth and Space Physics, 3(48), 541-555.
Khosravi, H., Javan Doloei, G., Safari, M., Shahrokhim, E., (2019). Seismic analysis and determination of upper crustal structure of Fariman region using 3D seismic tomography. The First National Conference on Signal and Image Processing in Geophysics, Shahrood University of Technology.
Kikuchi, M. & Kanamori, H. (1991). Inversion of complex body waves. Bulletin of the Seismological Society of America, 81, 2335-2350.
Mirzaei, N., Gao, M., & Chen, Y.T. (1998). Seismic source regionalization for seismic zoning of Iran: Major seismotectonic provinces. Journal of Earthquake Prediction Research, 7, 465–495.
Motaghi, K., Tatar, M., & Priestley, K. (2012). Crustal thickness variation across the northeast Iran continental collision zone from teleseismic converted waves. Journal of Seismology, 16, 253-260.
Motaghi, Kh. (2011). Investigation of the continental lithosphere structure - Northeast Iran. Ph.D. thesis, International Research Institute of Earthquake Engineering.
Nedaei, M., & Alizadeh, H. (2021). New insights into the 2017 Sefidsang earthquake by Coulomb stress change pattern and aftershock distributions: implication for active tectonics of NE Iran. Geopersia, 11(1), 23-42.
Niksejel, A., Shomali, Z.H., Cesca, S. and Moradi, A. (2021). Towards a regional, automated full moment tensor inversion for medium to large magnitude events in the Iranian plateau. Journal of Seismology, 25, 653-669.
Sokos, E.N. & Zahradnik, J. (2008). ISOLA a Fortran code and a Matlab GUI to perform multiple-point source inversion of seismic data. Computers & Geosciences, 34(8), 967-977.
Tchalenko, J.S. (1975). Seismicity and structure of the Kopet Dagh (Iran, USSR). Philosophical Transactions of the Royal Society, London, Ser. A, 278, 1-28
Zahradnik, J., & Sokos, E. (2018). ISOLA Code for Multiple-Point Source Modeling—Review. In: D'Amico, S. (eds) Moment Tensor Solutions. Springer Natural Hazards. Springer, Cham. https://doi.org/10.1007/978-3-319-77359-9_1.
Zahradnik, J. & Sokos, E.N. (2019). 'ISOLA code for multiple-point source modeling – review'. In: D'Amico, S. (Ed.), Moment Tensor Solutions: A Useful Tool for Seismotectonics. Springer.
Zahradnik, J., Serpetsidaki, A., Sokos, E., & Tselentis, G.A. (2005). Iterative deconvolution of regional waveforms and a double-event interpretation of the 2003 Lefkada earthquake, Greece. Bulletin of the Seismological Society of America, 95(1), 159-172.
Zahradnik, J., Sokos, E., & Tselentis, A. (2009). Quick identification of the fault plane for Mw 6.3, earthquake south of Crete, Greece July 1, 2009. Report to EMSC issued on July 1st.
Journal of Seismology and Earthquake Engineering
Volume 24, 3&4
August 2022
Pages 1-10

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