The earthquake of the century in Northwestern Europe: the Roermond, the Netherlands, earthquake of April 13, 1992

This earthquake, magnitude 5.9, caused structural damage and 40 casualties. It attracted attention because northwestern Europe had not experienced an earthquake of this size for 200 years. The earthquake nucleated at a depth of about 17 km on the northeastern boundary fault of the Roer Valley graben, part of the Lower Rhine embayment, which is one of two structural elements of the Rhine Graben System. This system is presently under either northeast-southwest tensional stress or northwest-southeast compressional stress. This is corroborated by the observed fault movement of the Roermond earthquake, indicating subsidence related to crustal extension. Furthermore, seismic data obtained from the main shock and aftershocks contain valuable information about crustal structure in the region. The cost of damage caused by the earthquake and the likely future earthquake risk are discussed. -G.E.Hodgson