Speaker
Dr
Päivi Mäntyniemi
(Inst Seismology Univ Helsinki Finland)
Description
There is a wide consensus on the magnitude, Ms5.4, of the Fennoscandian earthquake on 23 October 1904, which makes it the largest onshore/nearshore event in the region during the 1900s. In much of the available literature it is known as the Oslofjord earthquake. An earthquake of this magnitude is rare in the Fennoscandian Shield, so it is meaningful to extract all possible information about it.
At the time, seismic stations existed, although their spacing was not dense. Bungum et al. (2009) located the earthquake epicentre instrumentally in the vicinity of the Koster Islands by the border between Norway and Sweden.
The earthquake was widely felt in the southern halves of Norway and Sweden and northern Denmark, and also on the other side of the Baltic Sea in Finland, Estonia, Latvia and Lithuania as well as along a coastal strip of northern Poland and Germany. Several contemporary publications described the earthquake effects at different locations; even a few specific macroseismic surveys were initiated.
Much macroseismic data are thus available for the earthquake of 23 October 1904. However, the earthquake occurred on Sunday during mass, and in very many places macroseismic descriptions originated only from churches.
This ongoing investigation focuses on the damages caused by the earthquake. They are minor on the global scale, but interesting regionally when well documented. The present notion is that vulnerable structures could be affected at relatively long epicentral distances. Indirect fire hazard was reported from very long distances, which might have followed from cracked masonry parts of buildings.
Reference
Bungum H, Pettenati F, Schweitzer J, Sirovich L, Faleide JI (2009) The 23 October 1904 Ms5.4 Oslofjord earthquake: Reanalysis based on macroseismic and instrumental data. B Seismol Soc Am 99:2836-2854. doi:10.1785/0120080357
Primary author
Dr
Päivi Mäntyniemi
(Inst Seismology Univ Helsinki Finland)
