Seismic networks layout optimization for a high-resolution monitoring of induced micro-seismicity

The continuous monitoring of the space-time-magnitude evolution of seismicity is a crucial task to assess the geo-mechanical conditions of hydrocarbon reservoirs. It is fundamental to design optimized high-sensitivity and cost-effective seismic networks able to detect and locate low magnitude events with high accuracy. In Italy, after the concern for the 2012 Emilia earthquake, the government released the guidelines for monitoring the seismicity in areas surrounding subsurface industrial activities. In this work, we propose an optimization study for seismic monitoring networks based on the guideline requirements. We evaluated the performance, in terms of detection/location thresholds and events location errors, of different network layouts constructed by varying the station density and geometry and considering also the integration of seismic arrays. We simulated sets of seismic sources at different depths by varying magnitude and stress drop values. We considered two different values of noise level at the stations. The results show that the station density and the noise level represent the crucial parameters for the seismic network performances. The performances of a standard network comply the guidelines requirements in terms of detection/location thresholds. Only the integration of seismic networks with arrays allows to decrease the location errors of several hundreds of meters and to reach the location accuracy required by the Italian guidelines. We foresee the integration of standard networks with seismic arrays to achieve high performance in terms of detection capability and location accuracy