GNGTS 2018 - 37° Convegno Nazionale

GNGTS 2018 S essione 1.2 207 the descending oceanic plate at the Japan plate boundary (converging at 10 cm/yr) illuminate a seismogenic volume down to 25 km comparable with the 20 km obtained from our models. BDT depths obtained from our calculations are then used to infer the available seismic volumes and predict the potential stored energy that may be released during an earthquake (Fig. 3). This also depends upon convergence rate. A doubling of the BDT depth obtained increasing convergence rate from 1 to 10 cm/yr is associated with an eightfold increase of the volume. Available empirical relationships correlating seismic volumes and earthquakes magnitude (Bath Fig. 2 - Main results of numerical models. Distribution of BDT depths (pink area) from results of the whole set of models. Notice that beside convergence rate, fault dip controls the range of variation of the BDT depth values being greater for shallow dipping faults (depth varies until 12 km if the fault dips 15 and 5 km if the fault dips 40 depending on forced convergence rate). Fig. 3 - Sketch showing the volume involved in thrust faults earthquakes depending on BDT depth, hence on convergence rate. The doubling of the BDT depth determines an increase of the volume of at least four times, corresponding to an increase of 2 orders of magnitude of the released energy.