Normal, blue and red earthquakes—A new way of earthquake classification on the basis of body-wave magnitudes

Abstract

Monochromatic magnitudes, based on P- and on S-waves, provide a means to recognize differences in the spectral contents of body-waves radiated from earthquake foci. New, synthetic magnitude calibration functions taking into account periods of waves recorded, improve the consistency of magnitude figures assigned routinely to earthquakes. First results of a world-wide regionalization of earthquakes according to their spectral character are presented. Preponderance of short-period radiation in one class of earthquakes, and of long-period radiation in another is seen, if the radiation is compared with that of normal earthquakes.