LAUSR

Abstract The comparison of tiltmeter and strainmeter data in the periods of the strongest earthquakes with tropical cyclone activities in the World Ocean during January–April 2014 is made. Main features of the observed co-seismic tilt and strain processes are consistent with the results obtained for the strongest events during 1997–2004. The time-frequency data analysis and the comparison of the analysis results with the anomalous geomagnetic and ionospheric activity come to an agreement with the observed phenomena. The obtained results have allowed the triggering mechanism of seismicity to be proposed. The process begins as spatial and temporal swings of the regions of tropical cyclone origins and the basins of their activity. The powerful cyclone development accompanies a wide range of earthquake precursory phenomena, including abnormal behavior of ultra-wideband (0.002 mHz–3 Hz) Earth's oscillations, which can be recorded at far distances up to 1000–10,000 km. The daily dissipation energy of the most powerful tropical cyclone (hurricane, typhoon) is estimated to have same order of magnitude as the energy released by an event of Mw 7–9, as well, atmospheric depressions are big enough to trigger a forthcoming strong earthquake. The triggering mechanism could be caused by quasi-static and time-dependent surface loading that produces vertical tension and shear deformations. This loading affects the seafloor and coastline where they fall close to the adjacent tectonic plate boundaries.