The instrumental aspects of seismology.
• (n.) The mensuration of such phenomena of earthquakes as can be expressed in numbers, or by their relation to the coordinates of space.
Seis·mom'e·try noun The mensuration of such phenomena of earthquakes as can be expressed in numbers, or by their relation to the coördinates of space. 
seismometer, seismometry 1. A tool for measuring earthquakes and attendant phenomena; such as, earth tremors or ground movement. 2. A special seismograph equipped to measure the actual movement of the ground. See seismograph in this listing for more details.