The earthquake that shook central Sjælland, Denmark, November 6, 2001

Abstract

Earthquakes on Sjælland are in general small and seldom felt. The largest earthquakes in the Danish region occur in Skagerrak and Kattegat, and they are felt in NW Jylland (Thy) and in North Sjælland on average several years apart. A small earthquake measuring just 2.8 on the Richter Scale was felt and heard over a surprisingly large area of Sjælland, Denmark on November 6, 2001. The earthquake caused people to abruptly leave their houses near the epicenter, and minor damage to several buildings was observed. The felt area is oriented strongly asymmetrically with respect to the epicenter, but it correlates well with the local geology. Specifically the shaking was felt in a region where the depth to the Top Chalk surface is small, and the thickness of the Quaternary sediments is less than 50 m. In 1869 an earthquake was felt strongly in the exact same area, and contours separating the felt area from the area where nothing was felt coincide almost exactly for the two earthquakes. This supports that geology and not human subjectivity is the determining factor in delineating the felt area for this earthquake.