High S-wave attenuation anomalies and ringlike seismogenic structures in the lithosphere beneath Altai: Possible precursors of large earthquakes

This paper addresses inhomogeneities in the short-period S -wave attenuation field in the lithosphere beneath Altai. A technique based on the analysis of the amplitude ratios of Sn and Pn waves is used. High S -wave attenuation areas are identified in the West Altai, which are related to the source...

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Bibliographic Details
Published in:Izvestiya. Atmospheric and oceanic physics 2016-12, Vol.52 (8), p.806-815
Main Authors: Kopnichev, Yu. F., Sokolova, I. N.
Format: Article
Language:English
Subjects:
Anomalies
Climatology
Earth and Environmental Science
Earth Sciences
Earthquake prediction
Earthquakes
Fluids
Gas pipelines
Geophysics/Geodesy
Lithosphere
Marine
Natural gas
Pipeline route selection
Ratios
S waves
Seismic activity
Structures
Submarine pipelines
Wave attenuation
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Summary:This paper addresses inhomogeneities in the short-period S -wave attenuation field in the lithosphere beneath Altai. A technique based on the analysis of the amplitude ratios of Sn and Pn waves is used. High S -wave attenuation areas are identified in the West Altai, which are related to the source zones of recent large earthquakes, viz., the 1990 Zaisan earthquake and the 2003 Chuya earthquake. Associated with the Chuya earthquake, a large ringlike seismogenic structure had been formed since 1976. It is also found that ringlike seismogenic structures are confined to high S -wave attenuation areas unrelated to large historical earthquakes. It is supposed that processes paving the way for strong earthquakes are taking place in these areas. The magnitudes of probable earthquakes are estimated using the earlier derived correlation dependences of the sizes of ringlike seismogenic structures and the threshold values of magnitudes on the energy of principal earthquakes with prevailing focal mechanisms taken into consideration. The sources of some earthquakes are likely to occur near to the planned gas pipeline route from Western Siberia to China, which should be taken into account. The relationship of anomalies in the S -wave attenuation field and the ringlike seismogenic structures to a high content of deep-seated fluids in the lithosphere is discussed.
ISSN:0001-4338
1555-628X
DOI:10.1134/S0001433816080077