Publikationsdatum:
2016-01-30
Beschreibung:
The Lower Rhine Embayment in Central Europe hosts a rift system that has very low deformation rates. The faults in this area have slip rates of less than 0.1 mm yr –1 , which does not allow to investigate ongoing tectonic deformation with geodetic techniques, unless they cover very long time spans. Instrumental seismicity does only cover a small fraction of the very long earthquake recurrence intervals of several thousands of years. Palaeoseismological studies are needed to constrain slip rates and the earthquake history of such faults. Destructive earthquakes are rare in the study area, but did occur in historic times. In 1755/1756, a series of strong earthquakes caused significant destruction in the city of Düren (Germany) and the surrounding areas. In this study we document palaeoseismological data from the nearby Rurrand Fault. In contrast to earlier studies on the same fault, we found evidence for a surface rupturing earthquake in the Holocene, and we identified at least one more surface rupturing event. Our study shows that the Rurrand Fault currently accommodates deformation in earthquakes rather than by creeping. The coseismic offsets were determined to be between less than 0.5 m per event. We assign maximum possible magnitudes of M w 5.9–6.8 for the Rurrand Fault and a slip rate of at least 0.02–0.03 mm yr –1 for the last ~130–50 kyr. The surface ruptures did not occur at the main fault trace that has a clear morphological expression due to older tectonic motions, but on a younger fault strand in the hanging wall of the main fault. Terrain analyses based on 1 m resolution airborne LiDAR data have been used to image the subtle morphological expression of this young fault zone. Georadar and electric resistivity tomography were applied to image the fault zone at depth and to test if these shallow geophysical methods can be used to identify and trace the fault zone. Georadar failed to produce reliable results, but geoelectrics were successfully applied and allowed us to retrieve slip rate estimates. Our results indicate that the Düren 1755/1756 earthquakes did not produce surface ruptures at the Rurrand Fault, either because they did not rupture the surface at all, or because they occurred at another, neighbouring fault.
Schlagwort(e):
Seismology
Print ISSN:
0956-540X
Digitale ISSN:
1365-246X
Thema:
Geologie und Paläontologie
Publiziert von
Oxford University Press
im Namen von
The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).
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