Problems of Engineering Seismology: article

Аnnotation: The seismic coda waves attenuation characteristics in the vicinity of the 1902 Shamakhi earthquake source adjacent zones of the Western Caspian Sea are studied. The relationship between the features of seismic processes and spatial inhomogeneities of the attenuation field is considered. The attenuation field is represented by the zones (blocks) having high Q-factor and being close to isometric in plan and by the linear zones of strong attenuation (weakened zones), which coincide with faults. Sources of the strongest earthquakes confined to the zones of maximum attenuation contrast. It was revealed that the structure of attenuation field agrees with the structure of S-wave velocity field: low-velocity anomalies correspond to low-Q zones. Monomeric volumes of intense localized seismicity, localized in weakened zones, are considered. In one of them, in the source zone of the 1902 Shamakhi earthquake, manifestations of processes of active deep degassing are observed: eruptions of mud volcanoes and swarms of earthquakes, which sources move upward during a series are recorded. It is noted that the most striking seismic events, and above all, the strongest 1902 Shamakhi earthquake, correlate with the minima of the Earth's rotation speed.