Local ground motion variations observed in the region of Roermond, the Netherlands, from aftershocks of the April 1992 earthquake

Abstract

The Roermond earthquake of April 13, 1992 (ML = 5.8) was felt in the proximity of the epicentre with different intensity in the Netherlands, Germany and Belgium. Within a few hours after the main shock, a temporary network of seven stations was installed in the epicentral area. About 200 aftershocks were recorded by these stations and also by the Belgian permanent network. The aftershock records in the graben exhibit large differences in ground motion, which may result from the source mechanism. However, significant amplifications were observed at some sites for very different earthquake locations. These results suggest that site effects have played a significant role in the ground motion. They are supported by spectral ratio computations between the signals recorded in the graben and at a reference bedrock station.