North-West Bandar-Abbas earthquake doublet (Mw 6.1, 6.4) and its source identification

Document Type : Research Article

Authors

1 Ph.D. student, International Institute of Earthquake Engineering and Seismology, Tehran, Iran

2 M.Sc. Graduate, International Institute of Earthquake Engineering and Seismology, Tehran, Iran

3 Associated proffesor, International Institute of Earthquake Engineering and Seismology, Tehran, Iran

4 Assistant Professor, International Institute of Earthquake Engineering and Seismology, Tehran, Iran

Abstract

Recording, processing and identifying the parameters of independent earthquakes larger than Mw = 4 using advanced equipment, software and professional experts, can be calculated nowadays in less than 10 minutes automatically in the Iranian plateau. Double earthquake of November 14, 2021 with a small time difference (less than 90 seconds) occurred at a very close distance with magnitudes of 6.1 and 6.4, respectively. The calculation of the parameters of location, time and magnitude of the first event, in addition to the calculation of its focal mechanism parameters, was made possible with the help of semi-automatic or automatic software. However, the interference of the seismic phases of the first event with the second one in farther stations poses a serious challenge to the automatic and semi-automatic calculation of location, origin time, magnitude, as well as the parameters of the focal mechanism of the second event. In this study, by merging recorded seismograms and accelerograms in seismic stations within the country, the parameters of this double earthquake and their two main aftershocks with magnitudes of 5.1 and 5.4 have been calculated. In addition, the calculation of the focal mechanism of these four events is carried out based on the polarization method of the first P-wave polarity, the amplitude ratio of P and S waves and the modeling of seismic moment tensor. The results of this study show that according to the locations and focal mechanisms calculated for the double earthquake and both major aftershocks, the activity of the Handun basement fault, which is probably related to the formation of the Handun salt dome, caused double earthquakes of November 14, 2021 and its two main aftershocks in the northwest of Bandar-Abbas, south of Iran.

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References

Astiz, L., and Kanamori, H., 1984, An earthquake doublet in Ometepec, Guerrero, Mexico: Physics of the Earth and Planetary Interiors, 34(1–2), 24–45, doi: 10.1016/0031-9201(84)90082-7.
Bahroudi, A., and Koyi, H. A., 2003, Effect of spatial distribution of Hormuz salt on deformation style in the Zagros fold and thrust belt: an analogue modeling approach: Journal of Geological Society of London, 160, 719-733.
Berberian, M., 1995, Master “blind” thrust faults hidden under the Zagros folds: active basement tectonics and surface morphotectonics: Tectonophysics, 241(3–4), doi: 10.1016/0040-1951(94)00185-C.
Edgell, H. S., 1996, Salt tectonism in the Persian Gulf basin, in Alsop, G. I., Blundell, D. J., and Davison, I., eds., Salt Tectonics: Special Publication of Geological Society, London, 100, 129-151.
Falcon, N. L., 1961, Major earth-flexuring in the Zagros Mountains of south-west Iran: The Quarterly Journal of the Geological Society of London, 117, 367-376.
Ghods, A., Shabanian, E., Bergman, E., et al., 2015, The Varzaghan–Ahar, Iran, Earthquake Doublet (Mw 6.4, 6.2): implications for the geodynamics of northwest Iran: Geophysical Journal International, 203, 522–540, doi: 10.1093/gji/ggv306.
Haynes, S. J., and Mcquillan, H., 1974, Evolution of the Zagros suture zone, southern Iran: Geological Society of America Bulletin, 85, 739-744.
Hessami, K., Koyi, H. A., and Talbot, C. J., 2001, The significance of strike-slip faulting in the basement of the Zagros fold and thrust belt: Journal of Petroleum Geology, 24, 5-28.
Hessami, K., Nilforoushan, F., and Talbot, C. J., 2006, Active deformation within the Zagros Mountains deduced from GPS measurements: Journal of the Geological Society, 163, 143–148.
Ilaghi, H., Yamini-Fard, F., and Tatar, M., 2010,  Aftershock analysis of the March 25, 2006, Fin earthquake, MW = 5.9 (Zagros - Iran): Iranian Journal of Geophysics, 4(1), 17-32.
Jackson, J., 1980, Reactivation of basement faults and crustal shortening in orogenic belts: Nature, 283, 343-346.
Jahani, S., Callot, J. P., de Lamotte, D. F., and Letouzey, J., 2007, The Salt Diapirs of the Eastern Fars Province (Zagros, Iran): A Brief Outline of their Past and Present, in Thrust Belts and Foreland Basins, 10.1007/978-3-540-69426-7(Chapter 15), 289–308, doi:10.1007/978-3-540-69426-7_15.
Jahani, S., Callot, J. P., Letouzey, J., and de Lamotte, D. F., 2009, The eastern termination of the Zagros Fold-and-Thrust Belt, Iran: Structures, evolution, and relationships between salt plugs, folding, and faulting: Tectonics, 28(6), 1–22, https://doi.org/10.1029/2008TC002418.
Koyi, H. A., Ghassemi, A., Hessami, K., and Dietl, C., 2008, Modelling the role of strike-slip faults in triggering Salt Diapirs in the Zagros fold-thrust belt: Journal of the Geological Society, London, 165, 1031-44.
Ni, J., and Barazangi, M., 1986, Seismotectonics of the Zagros continental collision zone and a comparison with the Himalayas: Journal of Geophysical Research, 91, 8205-8218.
Stöcklin, J., 1974, Possible ancient continental margins in Iran, in Burke, C., and Drake, C., eds., The Geology of Continental Margins: Springer-Verlag, New York, 873-877.
Talebian, M., and Jackson, J., 2004, A reappraisal of earthquake focal mechanisms and active shortening in the Zagros mountains of Iran: Geophysical Journal International, 156(3), 506–526, https://doi.org/10.1111/j.1365-246X.2004.02092.x.
Tatar, M., Hatzfeld, D., and Ghafory-Ashtiany, M., 2004, Tectonics of the Central Zagros (Iran) deduced from microearthquake seismicity: Geophysical Journal International, 156, 255–266.
Walker, R. T., Andalibi, M. J., Gheitanchi, M. R., Jackson, J. A., Karegar, S., and Priestley, K., 2005, Seismological and field observations from the 1990 November 6 Furg (Hormozgan) earthquake: a rare case of surface rupture in the Zagros mountains of Iran: Geophysical Journal International, 163, 567–579.
Zahradník, J., and Sokos, E., 2013, Evaluating centroid-moment-tensor uncertainty in the new version of ISOLA software: Seismological Research Letters, 84(4), 656–665, https://doi.org/10.1785/0220130002.
 
 
Iranian Journal of Geophysics
Volume 16, Issue 3
December 2022
Pages 89-103

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