Numerical DEM simulation of AE in plate fracture and analogy with the frequency of seismic events in SCRs

Abstract

The present paper examines, by Monte Carlo simulation employing the Discrete Element Method (DEM), the occurrence of micro-fractures and the evolution of damage, as cracks coalesce in large fractures, in a plate subjected to increasing stress. Numerical simulations results which in previous studies predicted successfully acoustic emission (AE) in laboratory samples, are compatible with the conclusions of the assessment of instrumental data in a Stable Continental Regions (SCR). The locations of AE sources, correlated with the growth of a diagonal fracture in the plate, are numerically determined. Seismic activity, on the other hand, is higher along inter-plate boundaries, decreasing in intra-plate regions (SCR) where it's prediction for engineering purposes presents great difficulties. The authors examined, in previous papers, instrumental seismic data for a 1200 km square region in the South American SCR, showing that the distribution of amplitudes is not exponential, as implicitly assumed in the Gutenberg-Richter law, and also that the largest events do not occur according to the distribution of small events. These contentions are also applicable to the numerical simulations described in the paper, illustrating similarity between the distributions of simulated AE events in the plate and seismic activity within a SCR.