Great and old earthquakes against great and old paradigms – paradoxes, historical roots, alternative answers

摘要

The similarity of the vertical displacements shown bycase-history extreme-magnitude earthquakes are scrutinised (Chile 1960,Alaska 1964, Sumatra 2004, ...). A common interpretation – an uprisingof lithospheric material – can be found, which is supported by theirregularities of the hypocentres distribution along the Wadati-Benioffzones. In the case of major South American earthquakes, a volcaniceruptions-earthquakes correlation is recognisable.Further support to this interpretation is the displacement of the Earth'sinstantaneous rotation pole – ≈3.0 mas (≈10 cm), observedat ASI of Matera, Italy – the seismic data (USGS) in the two days followingthe main shock, the geomorphologic data, and the satellite data ofuplift/subsidence of the coasts (IGG) make possible a new interpretation ofthe Great Sumatran earthquake (26 December 2004) based on the secondconjugate – nearly vertical – CMT fault plane solution.All this converges toward different causes of seismogenetic processes,strongly supporting a deep origin of disturbances, fluxes of materialsleading to more or less sudden movements of masses, and phase changes, whichlead to either earthquakes or silent-slow events in Wadati-Benioff zones. Areinterpretation of the geodynamics of the active margins and mountainbuilding is proposed with a heuristic model that does not resort tolarge-scale subduction, but only to isostatic uplift of deep materialintruding between two decoupling plates in a tensional environment.Concomitant phase changes toward less-packed lattice and buoyancy effectcaused by the Clapeyron slope can help the extrusion of material over them.s.l., constituting an orogenic process. The phenomena expected to occur inthe model directly and harmoniously contribute to the building up of thesurface geophysical and geomorphological features of the orogenic zones.