Abstract
Seismicity migration is studied by a new method based on space-time diagrams and a combination of cluster and regression analyses. Data from the global and Baikal regional earthquake catalogues are analysed with the application of the specially designed geographic information system (GIS) in order to establish parameters and mechanisms of seismicity migration in space and time. We study the migration of seismic events in the following geostructural systems: the Baikal rift zone (BRZ), the area between BRZ and the Indo-Eurasian interplate collision zone, the area between BRZ and the West-Pacific seismic foci Benoiff zone, and two segments of the Middle Atlantic ridge. As evidenced by the obtained results, studying regimes of seismic migration provides for analyses of space-time distribution of seismic energy in the fault-block structure of the lithosphere and facilitates more detailed studies of the origin of deformation waves and mechanisms of the seismotectonic regime of the Earth. Forward (from the equator) and backward (towards the equator) migration of seismic events are established in all the regions under study. It is assumed that this phenomenon may result from regular changes of the polar compression of the Earth due to variations of its rotation regime. Besides, it is revealed that energy clusters of migration are regularly generated, and the regularity may be related to the 11-year cycle of the solar activity which impacts the seismic regime. We discuss the need to study the interference of wave deformations in the lithosphere which are initiated by several external energy sources. It is proposed to consider the regimes of planetary seismicity migration as a reflection of redistribution of endogenic (primarily heat) energy of the Earth during the destruction of its lithospheric shell under the impacts of cosmogenic factors via triggering mechansms. With reference to our positive experiences of applying the proposed concept to BRZ, we consider possibilities of using the seismicity migration data for prediction of earthquakes in the planetary and regional scales.
Highlights
Earthquake migration, that was first recognized in the middle of the 20th century, has been revealed in all the seismic belts of the Earth [Mogi, 1968; Ruzhich et al, 1989; Ruzhich, Levina, 2012; Vikulin et al, 2000; Chery et al, 2001; Bykov, 2005; Liu et al, 2010; Levina, Ruzhich, 2010; Levina, 2011; Vikulin et al, 2012; Sherman, 2013, 2014; Novopashina, 2013; Novopashnina, San’kov, 2015; Dolgaya, Vikulin, 2015]
We study the migration of seismic events in the following geostructural systems: the Baikal rift zone (BRZ), the area between BRZ and the Indo-Eurasian interplate collision zone, the area between BRZ and the West-Pacific seismic foci Benoiff zone, and two segments of the Middle Atlantic ridge
The first column of the table gives a list of clusters identified in the diagram
Summary
Earthquake migration, that was first recognized in the middle of the 20th century, has been revealed in all the seismic belts of the Earth [Mogi, 1968; Ruzhich et al, 1989; Ruzhich, Levina, 2012; Vikulin et al, 2000; Chery et al, 2001; Bykov, 2005; Liu et al, 2010; Levina, Ruzhich, 2010; Levina, 2011; Vikulin et al, 2012; Sherman, 2013, 2014; Novopashina, 2013; Novopashnina, San’kov, 2015; Dolgaya, Vikulin, 2015]. The term of 'earthquake migration', has not been unanimously accepted due to the fact that earthquake foci and epicentres do not migrate but occur in the inter-block medium and are manifested in implicit patterns and trends in space and time. Parameters of seismic migration were estimated from data on rare separate epicentres of strong earthquakes, while the analysed data ranges were small and not representative statistically. Among the synonyms, the term of 'seismicity migration' seems preferable for describing space-time patterns and statistically significant trends in the distribution of seismic events that occur between the hierarchically regular blocks of the lithosphere. In our previous publications [Levina, Ruzhich, 2010; Levina, 2011; Ruzhich, Levina, 2012], it was shown that estimations of the velocity of earthquake foci migration can differ significantly depending on grouping of seismic events by their energy levels. Due to the lack of a uniform approach to studies of seismic migration, an adequate comparison of published regional data and estimations is impossible, and geodynamic conditions causing the seismicity migration phenomena during the destruction of the lithosphere cannot be reliably clarified
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