Moment magnitude (Mw) from hydrophone records of low energy volcanic quakes

Abstract Earthquake magnitude calibration using hydrophone records has been carried out at Campi Flegrei caldera, an active area close to the highly populated of Naples city, partly undersea. Definite integrals amplitude spectra, between limits 1 and 20 Hz, were calculated on a set small volcano-tectonic earthquakes with moment magnitudes ranging from 3.3. The coefficients linear relationship logarithm these obtained by optimization, thus defining useful equation calculate record spectra. This method could be easily exported other volcanic areas, where submerged volcanoes are monitored networks hydrophones seismic sensors land. proposed approach allows indeed measurements occurring sea, adding information seismicity volcanoes.