Recent developments of ocean bottom seismic and electromagnetic instruments operated by ROV

Essential information to understand geodynamic processes is provided from imaging the Earth's interior by using geophysical observations. Recently, we have developed two geophysical instruments to exploit oceanic mantle, the BBOBS-NX (broad-band ocean bottom seismometer of next generation) and the EFOS (Earth's electric field observation system), both of them are operated by ROV (remotely operated underwater vehicle). They provide data of much higher quality than conventional instruments such as BBOBS (broad-band ocean bottom seismometer) and OBEM (ocean bottom electro-magnetometer).