29 small, underwater observatories, equipped with pressure sensors, seismometers and accelerometers, are installed directly on the fault-line off the coast of Osaka.
That sounds a silly suggestion, but that was precisely the idea adopted in some of the early instruments (seismometers) for recording earthquake waves.
To avoid this, NASA scientists plan to place 10 more seismographs on the lunar surface in order to find the calmest areas where tremors are least likely.
Scientists use a range of tools, from seismometers to satellite imagery, to track signs of unrest such as seismic activity, ground deformation, and gas emissions.