text: lem is the classification and period of movement along the faults. Step 5: Suitable empirical curves are selected in order to represent the alternation of ground motion in relation to the variables - distance (II), magnitude (M), and focal depth (h). The main parameters may be the macroseismic intensity (I), or acceleration (a), or particle velocity (u), or displacement (d). A major problem is the lack of reliable attenua- tion curves for the most active regions. If curves from other regions are used, the resulting hazard figures should be used with caution. The attenuation curves usually refer to bed- rock or to average ground condiUons. Step 6: The relationship between the average annual number (N) of earthquakes and their magnitude (M) defines the level of earthquake activity within the source area. The upper threshold magnitude limit (iVIm& is estimated with the aid of several techniques of varying reliability, e.g. Gumbel’s theory of extreme values, correlation of the lengths of active faults with (Mm&, curvature of the recurrence plots, etc. Step 7: Statistical models usually, as in the case of the Poisson model, assume independent events and a constant trend of earthquake activity, i.e. that the pattern of earthquake occurrence in the past will be repeated in the future. These assumptions are not strictly true and merely provide a first approximation, the reliability of which depends on the length of the sample. For mapping purposes the calculations are made for points of a grid and contours are then drawn. 14 FIGURE I: PLANNING FOR THE MITIGATION OF EARTHQUAKE DISASTERS GOVERNMENT AUTHORITIES NO OR NOT SURE of the seismic monitoring institution. l-----i Do adequate earthquuke-resistant regulations exist ? NO OR NOT SURE criteria for acceptable risk, and responsibilities for imple- mentation of emergency plans. f Formulate plans for post- earthquake disaster relief, EARTH SCIENTISTS AND EARTHQUAKE ENGINEERS 
analysis: The text appears to be discussing the process of assessing earthquake hazards and planning for disaster relief, which suggests a strong connection to natural phenomena and emergency response. The focus on scientific concepts such as seismic monitoring, attenuation curves, and statistical models also points towards a category related to science and technology.