For a destructive earthquake, the process of collecting and interpreting damage data and preparing a map of Modified Mercalli Intensities can take months. We hope that the CII map will serve as a useful first approximation to the Modified Mercalli Intensity map in the early hours and days following damaging earthquakes during which time the final Modified Mercalli Intensity maps are being prepared. Because there are major differences in the data and procedures used to assign the two types of intensities, the Community Internet Intensities cannot be considered to be identical to the USGS Modified Mercalli Intensities. Using the CII responses that we have collected for various historical and recent earthquakes, we can begin to put constraints on the intensities for low amplitude shaking. Since the instrumental intensities are derived directly from peak ground motion values, this figure shows how recorded peak motions relate to CIIs.
Fill corresponds to the intensity scale in the legend at the bottom of the figure.
Small circles show selected city locations as labeled. The Web page version of the map is shown in Figure 3. Fill corresponds to the intensity scale in the legend at the bottom of the figure. Small circles show selected city locations as labeled. Shading corresponds to the intensity scale in the legend at the bottom of the figure.