The Answer to a Deep(Focus Seismicity Riddle

The paradox of seismicity has long been known: the mechanism of ordinary fragile breakings cannot support realization of the earthquakes at depths of more than a few dozen kilometers. However, earthquakes occur much deeper. Various models that linked the occurrence of earthquakes with the release of fluid and phase transformations in the downgoing plates have been proposed to explain such events. However, the changes in the seismic mechanisms of earthquakes should be accompanied by the depth-associated changes in the focus parameters, whereas such changes have not been found until recently. The lack of such confirmation of the model suggestions prevents the finding of a solution for the mystery of deep-focus earthquakes. Recently, such changes that fit well with theoretically expected have been revealed. Thus, the almost century-old riddle of the nature of deep earthquakes has found its answer.

deep-focus earthquakes, solid state transformations, deep fluid regime, mechanism of failure at high parameters