| Abstrakt: |
Geodetic and seismological data are crucial for examining the kinematics and active tectonics in structural zones. The current tectonic stress field can be inferred from the focal mechanism stress inversion (FMSI) and the seismic and geodetic strain rates (SSR and GSR). In this study, a reliable focal mechanism solution for earthquakes from 1968 to 2020 and GPS data from 2006 to 2015 were used to calculate the direction and magnitude of maximum principal strain rates to evaluate the seismic potential of eastern Iran, where more than 10 strong instrumental earthquakes (Mw ≥ 6) have occurred over the past three decades. A new stress map was proposed for the study area by analyzing the weighted average of FMSI, SSR and GSR in which the direction of the mean stress was estimated at ~ N36 E. Results show that the northeast of the Lut block is generally controlled by the transpressional deformation zones with oblique faulting. Moreover, we observed left-lateral and right-lateral shearing as well as dip-slip movements in different parts of the area. According to the stress inversion results of focal mechanism solutions, the study area can be categorized into four main groups of stress regimes: strike-slip (43.75%), thrust (35.41%), normal (4.17%), and unknown or oblique faulting (16.67%). The estimated geodetic shear strain rates (GSSR) show a maximum shearing rate around the Abgarm and the Abiz (Ardakoul) right-lateral strike-slip faults in the boundary of the Sistan Suture Zone (SSZ) with the Afghan block. Seismic and geodetic strain rates were compared with seismic and geodetic moment rates (SMR and GMR) to investigate the seismicity pattern and the structural evolution of the area. The high seismic-geodetic moment-rate ratio of about 92.1% reflects a fully seismic deformation of the study region. According to our calculations, the northern part of the SSZ includes about 89.82% of these ratios, indicating high seismic behavior, while the northern part of the Lut block includes about 2.28%, which indicates an aseismic deformation in this part. The data analysis exhibits more significant seismic hazard along the Dorouneh fault zone and Sedeh, Shekarab, south Birjand, and Birjand faults. [ABSTRACT FROM AUTHOR] |
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