Application of Kriging Technique to Seismic Intensity Data

Spatial analysis, involving experimental semivariogram evaluation and
kriging interpolation, is performed on macroseismic intensity data assumed to represent
a regionalized variable. A semivariogram is modeled, showing that data components
act at different scale levels. Interpretation of the semivariogram in terms of
fractal dimension allows separation of the error component from other scaledependent
components. Use of an objective best spatial-range determination for filtering
eliminates the subjective choice that is usually based on data-sampling density,
permitting the reconstruction of the smoothed interpolated intensity field. Results are
given together with error estimation due to local variability and sampling-density
distribution. The method is first applied to synthetic macroseismic data with controlled
variable error content and sampling density: the ability to rebuild the original,
error-free intensity field is demonstrated. Then macroseismic data from an Italian
medium-intensity earthquake are analyzed and spatial intensity attenuation reevaluated.