Articles | Volume 11, issue 1
Nat. Hazards Earth Syst. Sci., 11, 135–143, 2011
https://doi.org/10.5194/nhess-11-135-2011

Special issue: Progress in research on earthquake precursors

Nat. Hazards Earth Syst. Sci., 11, 135–143, 2011
https://doi.org/10.5194/nhess-11-135-2011

Research article 11 Jan 2011

Research article | 11 Jan 2011

Underlying mechanism of precursory activity from analysis of upward earthquake migration

O. A. Molchanov O. A. Molchanov
  • Institute of Physics of the Earth, Russian Academy of Sciences (IPE RAS), Moscow, Russia

Abstract. In this paper we analyse the upward earthquake hypocentral migration in the ten known subduction zones and discuss a possible mechanism of such migration. The total time of the migration appears to range from 2.5 to 10 years. It leads to the estimation of the average velocity Vz~ 60−300 km yr−1. It probably corresponds to the movement of the forcing agent like stress or deformation wave from depths of the upper mantle (600–700 km) to the level of the lithosphere with subsequent initiation of fluid migration inside the crust to trigger shallow earthquakes. Averaged over all zones upward migration travel time is about 5 years (< Vz > ≈120 km yr−1) that coincides approximately with the period of characteristic temperature variation (El Nino) and crustal seismic periodicity in the Pacific region. These findings are helpful for the study of the seismic precursors and analysis of earthquake triggering.

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