Electromagnetic monitoring of the Earth's interior in the frame of the MEM Project

The MEM Project (Magnetic and Electric fields Monitoring) was activated in the INGV Observatory of L’Aquila since 2004. The principal purpose of the project is to create in Central Italy a network of observatories to monitoring the electromagnetic signals in the frequency band [0.001 Hz - 100 kHz]. This band includes natural signals (magnetic pulsations of magnetospheric origin, Earth-ionosphere resonance mode signals, atmospheric noise, and so on) and artificial signals (power line emissions, VLF radio transmissions, and so on). The innovative characteristic of the project is the approach chosen to study the complex problem concerning the representation of the spatial and temporal distributions of the electromagnetic fields in the band of interest. Both the distributions can be represented by some parameters containing the locations and the characteristics of the sources of the electromagnetic signals. When all the stations will be in operation the wide-band interferometry will be applied. Combining the simultaneous observations of the electromagnetic field measured in the stations of the network, we will be able to obtain detailed information about the investigated electromagnetic sources. A new measurement system has been developed to fulfil these requirements focusing on the automation of the measurements. The system is designed for long term recording of the electromagnetic fields in a wide frequency band. In the frequency band [1Hz - 100 kHz] the three components of the magnetic field and the three components of atmospheric electric field are processed in real time using DSP (Digital Signal Processing) techniques. In the frequency band [0.001 - 25]Hz the two components of the telluric field and the three components of the magnetic field are recorded as sampled (100Hz). One of the main scientific objectives of the MEM project is the long term monitoring of the geodynamical processes, such as the earthquakes, by the calculation of the Poynting vector, and the analysis of the magnetic transfer functions and impedance tensor. In the next years this kind of analysis can be useful to underline the possible correlation between the geodynamical processes and the local magnetic field anomalies.