A quantitative measure of the Modified Mercalli Intensity Scale for earthquakes in the western United States has been developed by correlating the peak seismoscope relative displacement response, Sd, with the reported site intensity, IMM. This correlation can be approximated by
for IMM ≦ VIII and is characterized by one standard deviation of about 0.7 S̄d. The data used in this study do not indicate an obvious type of dependence of Sd on local site conditions.
A method for computing the analog of the local earthquake magnitude, Mseismoscope, has been presented for possible use in strong-motion seismology and for scaling earthquakes by close-in measuremients, when other seismological instruments may go off scale.