investigating the mechanism of earthquakes in the iranian plateau using the gcmt catalogue

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.

investigating the mechanism of earthquakes in the iranian plateau using the gcmt catalogue

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.