Automatic Methods for Generating Seismic Intensity Maps

For many years the Modified Mercalli (MM) scale has been used to describe the observed effects of sizeable earthquakes on buildings and people. Initially isoseismal lines of the effects were added to maps by hand. Some objective methods have been proposed eg. DeRubeis et al. [14], Brillinger [2, 3, 4, 6], Wald et al.[33], Pettenati et al. [25]. The work presented here develops such methods further. In particular the ordinal character of the MM scale is specifically taken into account. Numerical smoothing is basic to the approach and methods involving splines, local polynomial regression and wavelets are illustrated. The approach presented also allows the inclusion of explanatory variables, for example site effects. The procedure is implemented for data from the 17 October 1989 Loma Prieta event.