seis·mo·graph 
(sīzmə-grăf′)
(sīzmə-grăf′)n.
An instrument for automatically detecting and recording the intensity, direction, and duration of a movement of the ground, especially of an earthquake.
seis·mogra·pher (sīz-mŏgrə-fər) n.
seis′mo·graphic (-grăfĭk), seis′mo·graphi·cal (-ĭ-kəl) adj.
seis·mogra·phy n.
seismographdata relating to the 1994 earthquake in Northridge, California