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

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.