On the aftershocks of the Great Sumatra-Andaman earthquake

TL;DR

This paper investigates the dynamics of aftershocks following major earthquakes, revealing that they can be triggered by Earth's seismic echoes and modulated by Earth's fundamental oscillations, supported by multiple earthquake analyses.

Contribution

It introduces the novel idea that aftershocks are influenced by Earth's seismic echoes and oscillations, supported by analysis of multiple significant earthquakes.

Findings

The strongest aftershock was likely triggered by a seismic echo around the Earth.

Earth's fundamental oscillation modulates aftershock sequences.

Analysis of multiple earthquakes supports these properties.

Abstract

Analysis of the Sumatra-Andaman earthquake on 26.12.2004 (M = 9) has allowed us to identify two non- trivial properties of the dynamics of aftershocks. First, the strongest aftershock (M = 7.2) was likely triggered by the round-the-world seismic echo of the main shock. The idea is that the surface waves propagating outwards from the main shock return back to the vicinity of the epicenter after having made a complete revolution around the Earth and induce there the aftershock. The second property is the modulation of the aftershock sequence by the fundamental oscillation of the Earth 0S2 excited by the main shock. Both results are supported by analysis of the Tohoku earthquake (11.03.2011, M = 9), as well as by the statistical analysis of the USGS earthquake catalog.