- Ground-motion model is:
where PGA is in m∕s2, c

_{1}= -2.09, c_{2}= 0.47, c_{3}= -0.039 and σ = 0.3 (note that the method given in the article must be followed in order to predict the correct accelerations using this equation). - Uses data (186 records) of Ambraseys and Douglas (2000, 2003) for M
_{s}≥ 5.8. Add 57 records from ISESD (Ambraseys et al., 2004) for 5.0 ≤ M_{s}≤ 5.7. - Investigates whether ‘magnitude-dependent attenuation’, i.e. PGA saturation in response to increasing magnitude, can be explained by PGA approaching an upper physical limit through an accumulation of data points under an upper limit.
- Proposes model with: a magnitude-independent attenuation model and a physical mechanism that prevents PGA from exceeding a given threshold. Considers a fixed threshold and a threshold with random characteristics.
- Develops the mathematical models and regression techniques for the truncated and the randomly clipped normal distribution.
- Reduces number of parameters by not considering site conditions or rupture mechanism. Believes following results of Ambraseys and Douglas (2000, 2003) that neglecting site effects is justified in the near-field because they have little effect. Believes that the distribution of data w.r.t. mechanism is too poor to consider mechanism.
- Performs a standard one-stage, unweighted regression with adopted functional form and also with form:
log
_{10}(PGA) = c_{1}+ c_{2}M + c_{3}r + c_{4}Mr + c_{5}M^{2}+ c_{6}r^{2}and finds magnitude saturation and also decreasing standard deviation with magnitude. - Performs regression with the truncation model for a fixed threshold with adopted functional form. Finds almost identical result to that from standard one-stage, unweighted regression.
- Performs regression with the random clipping model. Finds that it predicts magnitude-dependent attenuation and decreasing standard deviation for increasing magnitude.
- Investigates the effect of the removal of high-amplitude (PGA = 17.45m∕s2) record from Tarzana of the 1994 Northridge earthquake. Finds that it has little effect.