That's basically what the "seismic moment" is. The "moment magnitude" is just a logarithmic version of this, calibrated so that it gives similar results to the older scales (e.g. Richter local magnitude scale) for moderate earthquakes.
Actually those 2 are INTENSITY scales rather than MAGNITUDE scales (like the "Richter Scale"). The former measure ground shaking at a site, the latter measure the energy release of the earthquake itself at the source.
In response to the original comment, actually only really the media uses the expression "Richter scale" now, as there are many different logarithmic magnitude scales. The problem with the original Richter (or "local magnitude") scale is that it doesn't keep increasing with the amount of energy release (it "saturates"). Now seismologists/earthquake engineers usually use the "Moment Magnitude" scale which is directly related to the energy release. Once again, it's a logarithmic scale.
There are other magnitude scales such as body wave magnitude, surface wave magnitude... (can't think of more off top of head)
So in response to the first comment, yeah the "on the Richter scale" peeves me off too since it's well outdated!
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That's basically what the "seismic moment" is. The "moment magnitude" is just a logarithmic version of this, calibrated so that it gives similar results to the older scales (e.g. Richter local magnitude scale) for moderate earthquakes.
Actually those 2 are INTENSITY scales rather than MAGNITUDE scales (like the "Richter Scale"). The former measure ground shaking at a site, the latter measure the energy release of the earthquake itself at the source. In response to the original comment, actually only really the media uses the expression "Richter scale" now, as there are many different logarithmic magnitude scales. The problem with the original Richter (or "local magnitude") scale is that it doesn't keep increasing with the amount of energy release (it "saturates"). Now seismologists/earthquake engineers usually use the "Moment Magnitude" scale which is directly related to the energy release. Once again, it's a logarithmic scale. There are other magnitude scales such as body wave magnitude, surface wave magnitude ... (can't think of more off top of head)
So in response to the first comment, yeah the "on the Richter scale" peeves me off too since it's well outdated!