Parameters Used to Obtain Earthquake MagnitudesParameterPS Values appropriate for mid-ocean ridge setting were taken from Toomey et al. [1985]. ?? is the rock density, c is the seismic wave speed, R is a radiation factor, K is a free-surface correction, Q is a two-element attenuation model with the first value assumed within 1 km of the receiver and the second value elsewhere, and f is the frequen