Monitoring Schumann resonance and other electromagnetic precursors of an earthquake with a virtual MIMO wireless sensor network

The frequency shift and amplitude change in Schumann resonance (SR) as a precursor of some moderate to strong earthquakes was observed and reported. Co-seismic SR variation could be occurring at even large magnitude and scale. In this study, we first model Schumann resonance associated with the occurrence of an earthquake and assess the SR variation recorded from an earth-based sensor network. Based on the computer simulation results, we then propose a wireless observation system to monitor SR as a potential precursor prior to an earthquake using a wireless sensor network (WSN). A WSN based on single antenna wireless sensor nodes are cooperated to establish a multiple-antenna WSN that is called virtual MIMO-WSN. Virtual MIMO-WSN is adjustable and tunable to monitor electromagnetic signals in different frequencies based on the number of the cooperative wireless sensor nodes. An electromagnetic map could then be generated by activating a virtual MIMO-WSN in specific direction by switching on/off certain sensor nodes based on their location (also known as beamforming). Cost effectiveness, system scalability, ease of deployment, adjustability in frequency tuning, and reliability in ELF/VLF direction-finding are the key design factors in virtual MIMO-WSN to overcome the bottlenecks in the existing techniques for ELF/VLF monitoring systems. Simulation results are used to evaluate these quality indices of the proposed virtual MIMO-WSN.