S-wave attenuation anomalies and ringlike seismogenic structures in the lithosphere beneath Altai: possible precursors of large earthquakesстатья
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Дата последнего поиска статьи во внешних источниках: 20 марта 2018 г.
Местоположение издательства:Road Town, United Kingdom
Первая страница:806
Последняя страница:815
Аннотация:Abstract⎯This paper addresses inhomogeneities in the short-period S-wave attenuation field in the litho-sphere beneath Altai. A technique based on the analysis of the amplitude ratios of Snand Pnwaves is used.
High S-wave attenuation areas are identified in the West Altai, which are related to the source zones of recent
strong 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 strong 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 depen-dences of the size 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 earth-quakes 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 seismo-genic structures to a high percentage of deep-seated f luids in the lithosphere is discussed.