Power spectra and geographical distribution of short-period microseisms in Sweden

Summary Microseisms recorded by short-period vertical-component seismographs in a network of permanent and temporary stations in Sweden are investigated by means of their power spectra. The geographical distribution of the microseisms is explained in terms of models involving line sources. A good fit to the observations is obtained by locating the line sources along the surrounding oceanic coasts. The Norwegian west coast is of dominant importance for medium- and long-period microseisms, whereas for the short-period ones also coasts of smaller sea basins, as the Baltic Sea and the Skagerrak, are of significance. As a consequence, it is found that short-period microseisms are largest at stations on or near oceanic coasts, and that the smallest microseisms occur at inland stations.