Comparison of Microseisms in Greenland, Iceland, and Scandinavia

Abstract

Microseismic amplitudes and periods recorded at Scoresby-Sund, Reykjavik, Bergen, and Uppsala in seven different cases from the years 1949–1950 are studied. At all stations the polar air is of essential importance for the generation of microseisms, whereas there is in general no close connection with the cyclone centres themselves. A coast effect is of importance for Scandinavia, whereas the source for microseisms recorded at Scoresby-Sund is located over the open ocean within the polar air. Standing ocean waves may be of importance at the Norwegian coast but in many cases not on the open ocean. The microseismic waves propagate much farther over the continent than along the ocean bottom. The microseismic periods in Scandinavia vary generally in parallelism with the amplitudes, in Iceland and Greenland generally not. Period minima and rapid amplitude increases are observed in Scandinavia when cold fronts cross the Norwegian coast. There is no sign of microseismic barriers in the Atlantic outside Scandinavia. The microseisms at Scoresby-Sund have a regular, group character; at the other stations they are generally continuous.