an accelerograph for recording strong earthquake motion in three mutually perpendicular directions is disclosed . an electromagnetic starter is provided for use particularly with the accelerograph to initiate recording and to continue recording for an adjustable period of time of from 6 to 15 seconds after the last shock . the starter may comprise a single magnetically activated element which is disposed to respond to the first and subsequent p - waves , or it may comprise three such elements , one vertically oriented to respond to movements in the z - axis , and two horizontally oriented to respond to movements in the x and y - axes . such starters may also be employed to open or shut off switches for any type of equipment or apparatus which should or should not be operating during an earthquake or immediately thereafter . the accelerograph itself not only may produce recordings on light sensitive paper , but because of its utilization of electromagnetic elements which react to vibrations , it may also produce electrical outputs proportional to the intensities of the vibrations to which the accelerograph is subjected . these electrical outputs may be recorded on a magnetic tape or transmitted to a central earthquake intelligence center for direct recording , computerization or visual display at that location .