MACROSEISMIC PRACTICE IN SLOVENIA

In 1986, a project was started concerning the improvement of macroseismic data management in Slovenia. It was decided to establish a network of collaborators all over Slovenia (20 251 km(2), approx. 2 million inhabitants), dense enough to allow the use of the MSK scale. Since the uniform spatial distribution with desired density of collaborators is hard to achieve, several methods are being used to obtain new collaborators. At present we have approximately 4100 collaborators in our computer supported database. When an earthquake is felt in Slovenia, the seismologist decides to what areas the questionnaires are to be sent. The prospective observers can be chosen by two criteria: density and quality marks. The density mark allows us to choose a number of observers in the same town or village, based mostly on the quality of answers and demographic conditions. The quality mark is computed, combined with the previous marks, and updated every time a completed questionnaire is returned. The average number of shocks for which the questionnaires are being sent is about 25 per year during the normal seismic activity. The average number of questionnaires is approximately 300 per event. The percentage of the returned questionnaires is above 66%. A user-friendly, interactive program has been developed to manage the database with information about collaborators, to select an area, density and quality threshold of inquiry, and to print addresses onto questionnaires.