What's the unit of the seismic measurements?

Much like sunlight contains different colors that can be split apart with a prism, seismic waves contain many different "frequencies" that we can record with specially "tuned" seismometers. you can read  the below link it will give you good guide

http://eqseis.geosc.psu.edu/~cammon/HTML/Classes/IntroQuakes/Notes/seismometers.html

best regards

Berhanu 

There are two different seismic scale commonly used today. Magnitude scale measures the original energy of an earthquake, and Intensity scale measures the intensity of shaking occurring at any given point on the Earth's surface.

Richter magnitude scale, or Richter scale, assigns a magnitude number to quantify the energy released by an earthquake. It is a base-10 logarithmic scale. More info on Wiki: https://en.wikipedia.org/wiki/Richter_magnitude_scale

Best regards,

Djordje