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. 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 coseismic offsets were determined to be between less than 0.5 m per event. Our study shows that the Rurrand Fault currently accommodates deformation in earthquakes rather than by creeping. 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. In this study we document palaeoseismological data from the nearby Rurrand Fault.
#Res2dinv startime series#
In 1755/1756, a series of strong earthquakes caused significant destruction in the city of Düren (Germany) and the surrounding areas. Destructive earthquakes are rare in the study area, but did occur in historic times. Palaeoseismological studies are needed to constrain slip rates and the earthquake history of such faults. Instrumental seismicity does only cover a small fraction of the very long earthquake recurrence intervals of several thousands of years. 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. This interpretation is consistent with previous conceptual models from studies in boreal regions.The Lower Rhine Embayment in Central Europe hosts a rift system that has very low deformation rates. The results presented here show the potential for geophysical methods to infer formational processes in peatlands, showing the presence of a series of isolated basins that later coalesced into a single peat landform. Both indicate bog formation from a lake with four deeper depressions, that are separated by glacial deposits. The complementary geophysical methods proved to be an efficient approach with which we can delineate the peat morphology and the underlying stratigraphy.
The peat depressions are underlain with larger clayey depressions reaching more than 20 m in thickness and represent lake sediments. In contrast, clayey sediments with low resistivity are found below the peat. The ERT indicated similar peat depths peat responds with high electrical resistivity. A comparison of the depths obtained using GPR and the peat probe reveals that the results of both methods correspond well in most locations.
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The reach of the GPR was complemented with manual peat probing. The edges of the bog are flat, with peat thickness ranging from 2 to 4 m. Within the depressions the peat reaches a depth of 6–9 m. The GPR results reveal four depressions within the peat bog, which are separated by elevated ridges. Information on the stratigraphy below the peat/clay boundary was acquired by applying electrical resistivity tomography (ERT). Ground penetrating radar (GPR) was used to determine the peat thickness and morphology of the Šijec bog on the Pokljuka plateau in Slovenia, which will serve as a basis for further geochemical studies. To determine past records, data on peat stratigraphy and bog development are needed. Owing to their anoxic environment, peatlands play an important role in the preservation of records documenting past atmospheric depositions.
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