seismometry

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The scientific study and recording of earthquakes.

from The Century Dictionary.

• noun The theory and use of the seismometer; more generally, the scientific study of earthquake phenomena by the aid of observations made either with or without the use of seismometric instruments.

from the GNU version of the Collaborative International Dictionary of English.

• noun The mensuration of such phenomena of earthquakes as can be expressed in numbers, or by their relation to the coördinates of space.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The numerical or spatial measurement of earthquakes.