ON THE SHALLOW DEPTH QUALITY FACTORS (QP, QS, QC) IN FARIMAN AREA USING AFTERSHOCKS OF MW6.0 EARTHQUAKE ON APRIL 05, 2017

High frequency quality factors Qc, Qp and Qs have significant role to study the simulation of the strong ground motion,seismic hazard analysis and seismic zoning. The 2017 April 5 Mw 6 Do Qaleh Fariman earthquake occurred southeast of the megacity of Mashhad, the center of Khorasan –e Razavi province, at the southern boundary of Kopeh-Dagh. Immediately after Do Ghaleh earthquake, International Institute of Earthquake Engineering and Seismology (IIEES) have decided to deploy an intensive local seismic network in the affected area of the Fariman to record all aftershocks (as shown in Figure 1). The IIEES temporary seismic network was deployed from 6th of April to 12th of May 2017 with 16 three-component seismometer of type LE-3D/20s Lenartz Company and 3 CMG-5TD Guralp accelerometers, which have recorded all events continuously with a sampling rate of 0.005 sec. First, all events were located after windowing and reading the arrival time phases. Then, the initial speed model was optimized based on a number of events with azimuthal gap less than 120 degrees. An optimized velocity structural model was used to determine the relocation of all seismic events. In the next step, 50 earthquakes, whose waveforms had a signal to noise ratio of more than three, were selected. The QC, QP, and QS quality parameters of the selected earthquakes werecalculated. In this study, single back scattering method was used to calculate QC which results is presented in Figure 1. The spectral ratio of the source Broun’s model was used to calculate the body wave quality factors (i.e. Qp & Qs).

کلیدواژه ها:

Body wave ، Coda wave ، Quality factor ، Fariman ، Iran