Recently, SVT Västernorrland has been able to tell about several earthquakes in the county. However, according to the seismologists, the number of earthquakes has not increased, however, they have occurred in more densely populated areas.

- Seismic activity varies over time and is not completely constant, but lately there have been some more severe earthquakes in Västernorrland. They have also been close to buildings and thereby felt by more, says Björn Lund, who is a university lecturer in seismology.

Inheritance from the Ice Age

The Swedish National Seismic Network (SNSN) consists of 65 seismic stations spread from Skåne in the south to Torneträsk in the north. These are connected to a computer in Uppsala via the network. On average, one to two earthquakes per day are recorded here in Sweden. This year, 468 pieces have been registered so far.

The vast majority are smaller earthquakes with a magnitude less than 2.0 and are usually not noticed on the ground surface. Västernorrlänning, however, has a great chance of experiencing a quake, which is probably a legacy after a giant quake a long time ago.

- The coastal route from Gävle to Haparanda is very active and we don't really know why. Sweden's most sesimologically active area is Burträsk outside Skellefteå. There we know that there was a big earthquake at the end of the ice age about 10,000 years ago, up 7 on the Richter scale. After that there are crack zones along the coast that are sensitive and that move more easily.

The great earthquake thus cracked the rock along the coast and the parts can now move more easily than the ground in other places.

Information and research

The information from seismic network stations is used for a variety of purposes, for example to make risk assessments to the mining industry. But one should also be able to inform citizens about what happened when there was a quake.

The network is of course also used for research on how and why earthquakes occur. Among other things, they study the interaction between the movements of the continental plates and the land rise after the inland ice. But Björn Lund believes that the land increase has little significance for the occurrence of earthquakes.

The archeology of the quake

The researchers at SNSN would like to receive reports from people who felt that the ground was shaking. They want to know how it felt and where it happened. It may feel like an old-fashioned method when you now have 65 stations with modern measuring equipment, but Peter Lund explains that it is about understanding historical earthquakes.

- Before the 60s, we only have this kind of observations. In order to be able to calculate how powerful the earthquakes really were, we need the same kind of observations today from earthquakes that we know how powerful they are, says Björn Lund.