A Trial observation of the EM-ACROSS signal for the long-distance transmission

Nakajima, Takahiro; Nagao, Hiromichi*; Sayanagi, Keizo*; Noda, Yoichi*; Nagao, Toshiyasu*; Kumazawa, Mineo; Hasada, Yoko*

Observation test was successfully made on the faint EM-ACROSS signals transmitted through the Earth's crust over the distance of 30 km. We transmitted a set of three sine waves around 1Hz from the grounded wire source with the dipole moment 4A 150m. The signal level observed at the distance of 30 km was in the order of 0.01pT, which is 10 lower than the average level of environmental electromagnetic noise at the observation sites. The signal-to-noise ratio (S/N) of the observations becomes up to 5 by means of the optimized stacking of the raw observation data for the 40 days. signal-to-noise ratio (S/N) becomes larger. The result of this trial observation becomes a substantial experience for the monitoring of the area of earthquake generation or volcanoes in the future.