Earthquake-triggered landslides at the Brunssummerheide, Limburg, the Netherlands: preliminary studies following the 1992 Roermond earthquake

Abstract

Two landslides occurred at the Brunssummerheide during, or shortly after the main shock of the 1992 Roermond earthquake. The Brunssummerheide is located 25 km south of the epicentre. An earthquake can reduce the stability of a hillslope in three ways: firstly, the ground acceleration from seismic waves forms an additional destabilizing force; secondly, the shear strength may be reduced by an increase of the pore pressure, and thirdly, an earthquake may cause the breaking of small cohesive bonds between soil particles, thus reducing the overall cohesion. Slope stability back-analyses were carried out to reconstruct the forces and processes during the event. Peak ground accelerations as predicted by empirical attenuation relationships are insufficient to cause instability of the slopes. It is concluded that an increase of at least 100% in the pore pressures was required to destabilize the two hillslopes.