Recent paleoseismic investigations in the Belgian part of the Roer-Lower Rhine graben system provide evidence of surface faulting caused by large earthquakes having occurred during the Holocene (less than 10,000 years ago). These observations raise questions about the classical approach of developing seismic hazard assessment based solely on historical and instrumental seismicity catalogues in regions considered erroneously as tectonically stable and show the importance of paleoseismic studies for estimating the potential of large earthquakes in these regions of Europe.
The objectives of the project are:
1) to establish a research method to identify paleoearthquakes in present-day low active seismic zones in Europe.
2) to obtain informations about the mechanical behaviour of seismogenic faults to quantify the return period and the dimensions of highly destructive earthquakes in these zones.
3) to establish a formulation of the results directly available for seismic hazard analysis.
To meet these objectives, the project considers regions with different seismotectonics context: The Roer Graben - Lower Rhine Embayment region and the Upper Rhine Graben characterized by extensive continental deformation and the Trentino-Alto Adige (eastern Alps) and the eastern Pyrenees which are regions under compressive tectonic stress field.
Description of the research project.
In the different test areas, the following tasks will be partly or completely (tasks 1, 3 and 5) realized:
1. Identification of seismogenic active faults by field investigations using new and already existing geologic, geochemical and geomorphological methodologies and data coupled with geophysical prospection (radar, seismic and electric) and remote sensing.
2. Detailed geomorphological analysis to establish a relationship between the age of surface rupturing earthquakes and the degradation of active fault scarps.
3. Excavation of trenches at adequate sites
- to identify Late Pleistocene and (or) Holocene coseismic surface faulting.
- eventually to identify single earthquakes and to study more than one single seismic cycle.
- to study induced deformations in low-consolidated sediments caused by paleoearthquakes.
4. Study of the potential effects of paleoearthquakes on archeological vestiges and speleothems.
5. Evaluation of the uncertainty in the parameters describing the paleoearthquakes as a basis for seismic hazard assessment.
Funding SchemeCSC - Cost-sharing contracts
86961 Chasseneuil Du Poitou
92265 Fontenay Aux Roses
3000 Louvain / Leuven
3508 TA Utrecht
3730 AE De Bilt
51429 Bergisch Gladbach