Investigating the Mechanism of Earthquakes in the Iranian Plateau Using the GCMT Catalogue

نوع مقاله : مقاله پژوهشی

نویسندگان

Department of Seismology, Institute of Geophysics, University of Tehran, Tehran, Iran.

چکیده

Routine estimates of the seismic moment (M0) by the Global Centroid Moment Tensor Project (GCMT) for large and moderate earthquakes, provide a valuable resource for tectonic analysis. In this research, the source type of 614 earthquakes that occurred in the Iranian plateau between 1676 and 2023, whose moment tensor solutions are available in the GCMT catalogue, was investigated. Here, earthquakes are grouped according to dip angle values of the T, P, and B axes which were taken from GCMT catalogue. The mechanism is considered as strike-slip or normal faulting when the dip angle of the B or P axes exceeds 60°, respectively. When the dip angle of T axis exceeds 50°, the mechanism is proposed as thrust faulting. The focal mechanism study of 614 earthquakes showed that about 55.4, 25.4 and 2.9 percent of them have reverse, strike-slip and normal mechanisms, respectively. The average value equal to 0.12 for  values of 614 earthquakes shows that the non-double-couple component in the deviatoric tensors is very small. Also, comparison of seismic moment estimated for 182 earthquakes by IRSC and GCMT, shows that there is an almost systematic bias in the seismic moment estimated by IRSC (Iranian Seismological Center). Seismic moment values reported by IRSC are lower than those determined by GCMT.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Investigating the Mechanism of Earthquakes in the Iranian Plateau Using the GCMT Catalogue

نویسندگان [English]

  • Mehdi Rezapour
  • Nasrin Rezaei
Department of Seismology, Institute of Geophysics, University of Tehran, Tehran, Iran.
چکیده [English]

Routine estimates of the seismic moment (M0) by the Global Centroid Moment Tensor Project (GCMT) for large and moderate earthquakes, provide a valuable resource for tectonic analysis. In this research, the source type of 614 earthquakes that occurred in the Iranian plateau between 1676 and 2023, whose moment tensor solutions are available in the GCMT catalogue, was investigated. Here, earthquakes are grouped according to dip angle values of the T, P, and B axes which were taken from GCMT catalogue. The mechanism is considered as strike-slip or normal faulting when the dip angle of the B or P axes exceeds 60°, respectively. When the dip angle of T axis exceeds 50°, the mechanism is proposed as thrust faulting. The focal mechanism study of 614 earthquakes showed that about 55.4, 25.4 and 2.9 percent of them have reverse, strike-slip and normal mechanisms, respectively. The average value equal to 0.12 for  values of 614 earthquakes shows that the non-double-couple component in the deviatoric tensors is very small. Also, comparison of seismic moment estimated for 182 earthquakes by IRSC and GCMT, shows that there is an almost systematic bias in the seismic moment estimated by IRSC (Iranian Seismological Center). Seismic moment values reported by IRSC are lower than those determined by GCMT.

کلیدواژه‌ها [English]

  • Focal mechanism
  • Moment tensor
  • GCMT catalogue
  • Iranian plateau
  • IRSC

مراجع

Ahmadzadeh, S., & Javan-Doloei, Gh. (2024). The high-frequency decay parameter Kappa (κ) in the Alborz Region using broadband seismic waveforms. Journal of Seismology. 1-18. 10.1007/s10950-024-10256-x.
Ammon, C.J., Velasco, A.A., Lay, T., & Wallace, T. (2021). Foundations of Modern Global Seismology, Elsevier, Academic Press. 
Al-Lazki, A., Seber, D., & Sandvol, E. (2002). A crustal transect across the Oman Mountains on the eastern margin of Arabia. GeoArabia, 7, 47-78.
Álvarez-Gómez, J. A., (2019). FMC—Earthquake focal mechanisms data management, cluster and classification. SoftwareX, 9, 299-307.
Apperson, K. D., & Frohlich, C. (1988). The effect of the plate boundary on average earthquake focal mechanisms in convergent margins, Geol. Soc., Abstr. Programs, 20, A236.
Berberian, M., & King, G.C.P. (1981). Towards a paleogeography and tectonic evolution of Iran. Can. J. Earth Sci. 18, 210–265.
Engdahl E.R., Jackson J.A., Myers S.C., Bergman E.A., & Priestley K. (2006). Relocation and assessment of seismicity in the Iran region, Geophys. J. Int., 167, 761–778.10.1111/j.1365-246X.2006. 03127.x
Dziewonski, A.M., & Anderson, D.L., (1981). Preliminary reference Earth model. Phys. Earth Planet. Inter. 25 (4), 297–356.
Dziewonski, A. M., & Woodhouse, J.H. (1983). An experiment in systematic study of global seismicity: Centroid-moment tensor solutions for 201 moderate and large earthquake of 1981, J. Geophys. Res., 88, 3247-3271.
Djamour, Y., Vernant, P., Bayer, B., Nankali, H.R., Ritz, J.F., Hinderer, J., Hatam, Y., Luck, B., Moigne, L.N., Sedighi, M., & Khorrami, F. (2010) GPS and Gravity Constraints on Continental Deformation in the Alborz Mountain Range, Iran. Geophys. J. Int, 183, 1287-1301. https://doi.org/10.1111/j.1365-246X.2010.04811.x
Frohlich, C. (1992). Triangle diagrams ternary graphs to display similarity and diversity of earthquake focal mechanisms. Phys Earth Planet Inter, 75 193-198.
Frohlich, C. (1994) Earthquakes with non-double-couple mechanisms, Science, 264(5160), 804-809.
Frohlich, C., & Apperson, K. D. (1992). Earthquake focal mechanisms, moment tensors, and the consistency of seismic activity near plate boundaries. Tectonics, 11 279-296.
Hessami, K., Jamali, F., & Tabassi, H. (2003). Major active faults of Iran, scale 1:25,000,000. Ministry of Science, Research and Technology, International Institute of Earthquake Engineering and Seismology, Iran.
Hosseini, H., Pakzad, M., & Naserieh, S., (2019). Iranian regional centroid moment tensor catalogue: Solutions for 2012–2017. Phys. Earth Planet. Inter., 286, 29-41.
Masson, F., Djamour, Y., Van-Gorp, S., Chery, J., & Tatar, M., Tavakoli, F., Nankali, H. and Vernant, P. (2006). Extension in NW Iran driven by MW 6.5, 6.4 Ahar-Varzghan doublet earthquakes 1203 the motion of the South Caspian Basin. Earth and Planetary Science Letters, 252, 180–188.
Mousavi, Z., Walpersdorf, A., Walker, R.T., Tavakoli, F., Pathier, E., Nankali, H., Nilfouroushan., F., & Djamour, Y. (2013). Global Positioning System constraints on the active tectonics of NE Iran and the South Caspian region, Earth and Planetary Science Letters, 377-378, 287–298.
Nouri-Delouei, M., & Gheitanchi, M.R., (2021a). Fault mechanisms and their frequencies during destructive earthquakes in Iran. Tectonics Journal, 5, 91-102.
Nouri-Delouei, M., & Gheitanchi, M.R., (2021b). Classification of Zagros earthquakes based on focal mechanism. Contributions to Geophysics and Geodesy, 51, 265-275.
Richards, J.P. (2015) Tectonic, magmatic, and metallogenic evolution of the Tethyan orogen: From subduction to collision, Oro Geology Reviews, 70, 323-345.
Richardus, P., & Adler, R.K. (1972). Map Projections North Holland, Amsterdam, 174 pp.
Stöcklin, J. (1968). Structural history and tectonics of Iran, a review, Am. Assoc. Pet. Geol. Bull., 52, 1229–1258.
Stampfli, G.M., & Borel, G.D. (2002). A plate tectonic model for the Paleozoic and Mesozoic constrained by dynamic plate boundaries and restored synthetic oceanic isochrons. Earth Planet. Sci. Lett. 196, 17–33.
Sokos, E., & Zahradník, J. (2008). ISOLA – A Fortran code and a Matlab GUI to perform multiple-point source inversion of seismic data, Comput. Geosci., 34, 967–977.
Sokos, E., & Zahradník, J. (2013). Evaluating Centroid-Moment-Tensor Uncertainty in the New Version of ISOLA Software, Seismological Research Letters, 84, 656-665.
Vavryčuk, V., & Hrubcová, P. (2017) Seismological evidence of fault weakening due to erosion by fluids from observations of intraplate earthquake swarms, J. Geophys. Res., 122, doi.org/10.1002/2017JB013958.
Vernant, P., Nilforoushan, F., Hatzfeld, D., Abbasi, M. R., & Vigny, C. (2004). Contemporary crustal deformation and plate kinematics in Middle East constrained by GPS measurements in Iran and northern Oman. Geophys. J. Int, 157, 381–398.
Zhai, Q. G., Jahn, B. M., Wang, J., Hu, P. Y., Chung, S. L., Lee, H. Y., Tang, S. H., & Tang, Y. (2015). Oldest Paleo-Tethyan ophiolitic mélange in the Tibetan Plateau. Geological Society of America Bulletin. 128 (B31296-1): 355–373. doi:10.1130/B31296.1.
Zoback, M.L., (1992). Stress Field Constraints on Intraplate Seismicity in Eastern North America. J. Geophys. Res. 92, 11761-11782.
فیزیک زمین و فضا
دوره 50، شماره 4
تاریخ انتشار الکترونیکی: 25 اسفند 1403
اسفند 1403
صفحه 115-124

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