I may have been 15 or 16 years old when, on a Sunday morning, I was sitting at home together with my mother and sister, and the floor began to move under us. The hanging lamp swayed. It was very strange. My father came into the room. “It was an earthquake,” he said. The center had evidently been at a considerable distance, for the movement felt slow and not shaky. In spite of a great deal of effort, an accurate epicenter was never found. This was my only experience with an earthquake until I became a seismologist 20 years later.
In the autumn of 1925, I became an assistant to N. E. Norlund, who shortly before had been appointed director of “Gradmaalingen” (a geodetic institution that was in charge of measuring the meridian arc in Denmark). He had become interested in establishing seismic stations in Denmark and Greenland. He wanted everything done in the best possible way, and much attention was paid to the time service. The best existing seismographs had to be used, and they were to be placed so that they were not strongly affected by disturbing movements, such as traffic, for example. Two solid buildings, part of the fortification system that surrounded Copenhagen, were made available. My first major task was to assist in the installation of the Galitzin-Willip seismographs there. On November 18, 1926, the seismic station was inaugurated. Its standard was high in comparison with existing seismic stations.