T he Richter scale is used to rate the magnitude of an earthquake -- the amount of energy it released. This is calculated using information gathered by a seismograph. The Richter scale is logarithmic, meaning that whole-number jumps indicate a tenfold increase. In this case, the increase is in wave amplitude.
The answer is astronomy. There is no ÓLOGY´ at the end of it.
Solute is what gets dissovled, in this case the salt, and the solVENT is whatever a material is dissolved into, in this case the water.