El Hierro Island Model–Canary–On a Basis of Joint Interpretation of Microseismic Sounding and Gravity Inversions

To study the deep structure of El Hierro Island, Canary Archipelago, we used a new microseismic sounding method based on the fact that Earth's crust heterogeneities disturb in their vicinity the spectrum of low-frequency microseismic field. At the Earth’s surface above the high-velocity heterogeneities the spectral amplitudes of definite frequency f are decreasing, and above the low-velocity ones they are increasing. The frequency f is connected with depth of heterogeneity deposition H and velocity of fundamental Rayleigh mode VR(f) by the following relation H = K*VR(f) /f, here К- is numerical factor close to 0.4. From microseismic data two large intrusive bodies were revealed beneath El Hierro Island. Joint interpretation of microseismic and gravimetric data and their comparison with previously obtained geological and geochemical data by other authors enables supposing that the eastern intrusive body relates to the early stage of the island formation. In the western body at the depths ~15 km the area with lowest seismic velocities could be revealed. We suggest that a modern magmatic chamber is located there.