Arthur Frankel 1994 <p><span>Observed relations between felt area and moment magnitude </span><strong>M</strong><span> for stable continental regions (</span><span class="sc">SCR</span><span>) and California earthquakes can be explained by a simple model with geometrical spreading, attenuation (</span><i>Q</i>⁻¹<span>), and earthquake stress drops that remain constant from </span><strong>M</strong><span> 4 to 8. Differences in the slopes of the observed felt area-</span><strong>M</strong><span> relations between SCR and California earthquakes are consistent with differences in </span><i>Q</i><span> between these tectonic settings. Fitting the felt area-</span><strong>M</strong><span> data to the model yields an estimate of </span><i>f/Q</i><span>, where </span><i>f</i><span> is the average frequency of minimum perceptible ground motion. Using fits to the data and instrumentally derived values of </span><i>Q</i><span>, I find that </span><i>f</i><span> is between about 2 and 4 Hz. I present an estimate of the spectral acceleration level associated with the lower limit of perceptibility.</span></p> application/pdf 10.1785/BSSA0840020462 en Seismological Society of America Implications of felt area-magnitude relations for earthquake scaling and the average frequency of perceptible ground motion article