S-WAVE ATTENUATION FIELD AND SEISMOTECTONICS OF EASTERN ANATOLIA
Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences.
Journal: Problems of Engineering Seismology
UDK: 550.34 + 550.341
Keywords: coda waves, Q-factor, S-wave attenuation field
Аnnotation: The seismic coda waves attenuation characteristic in theEastern Anatolia region were studied. The short-period coda waves about 400 earthquakes that had been occurring in theEastern Anatolia region since 1989 until 2018 were analyzed. In this work we used three-component digital records seismic events of more than 3.5 in magnitude, and epicentral distances are 10-600 km. S -wave attenuation was estimated from short-period coda envelopes (including those of Lg wave coda) at a frequency of ~1 Hz. The features of the structure of the S-wave attenuation field in the upper mantle near Lake Van are similar to those for other seismically active zones. The attenuation field is represented blocks with weak attenuation, being close to isometric in plan where the attenuation decreases in the direction from the boundaries to the central of the blocks ( Q -factor reaches 300-700) and strong attenuation zones. Among the zones of strong attenuation, usually linearly elongated, the most noticeable are the echeloned zone (north of 39 ° N), associated with the North Anatolian Fault, here Q