Abstract:Effects of stress perturbation on acoustic emission（AE） during fault friction are studied by using medium-scale experiments of rock friction,and the characteristics of seismicity caused by coseismic stress change and its implication in earthquake forecasting are discussed based on the experimental results.The experiments indicate that stress perturbation of square wave can obviously affect AE activity,it can trigger some AE events so that AE activity before stick-slip becomes stronger and occurs earlier.The effect increases with increasing average normal stress and perturbation amplitude,and perturbation effect from shear stress（increase） is more evident than that from normal stress（decrease）.In statistics,when stress perturbation is not applied,AE events usually occur just before stick-slip even if there are AE events,i.e.occurring when stress accumulation reaches above ~90%.When stress perturbation is applied,AE events occur earlier before stick-slip,i.e.occurring when stress accumulation reaches ~70% and even much earlier.The experimental results mean that whether the coseismic stress change caused by a strong earthquake can obviously affect strong seismic activity in its neighbour area,it is mainly depentent on if the absolute stress of faults comes close to instablity strength.Small earthquaks can reflect stress state of fault at certain extend,therefore,it is more reasonable to analyze earthquake potential by combing coseismic stress change and activity of small events.However,the uncertainty existing in the process should also be considered.
