NJG85-3-08
2005
The 31st of August 1819 Lurøy earthquake revisited
85
3
pp. 245-252
82-92394-21-4

The 31st of August 1819 Lurøy earthquake has, for a long time, been considered as the largest known historical earthquake in Fennoscandia, possibly even on the mainland of northern Europe. Triggered by a recent claim that the magnitude (MS) of this earthquake should be 5.1 rather than 5.8, which implies a reduction in radiated energy by about a factor of 10, we have reassessed the original macroseismic observations together with the published literature. Our conclusion is that a MS magnitude of 5.8 for the 1819 Rana region earthquake still remains a reasonable, justifiable and defendable estimate. Such a magnitude is moreover consistent with present hazard models for the region, which include the possibility that magnitude 6+ earthquakes can occur today in the most seismically active areas in Norway, such as the coastal parts of western Norway, Nordland and the Oslo rift zone. Rock avalanches and landslides, potentially triggered by earthquakes, could moreover generate tsunamis in fjords and lakes and constitute the greatest seismic hazard to society in Norway

0029-196X
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