Hohenzollerngraben

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The Hohenzollerngraben or Zollerngraben is a geological trench over 30 kilometers long and an average of 1.5 kilometers wide in the south-western Swabian Alb in Baden-Württemberg . It stretches in a north-westerly, i.e. Hercynian, direction across the area of ​​the Zollernalb district from the Alb plateau to the Alb foreland. The edge faults bordering the Hohenzollerngraben have a jump height of around 100 meters on the Alb plateau and up to 40 meters in the foreland. They fall inwards in a V-shape and close the trench at a depth of two to three kilometers.

Emergence

The Hohenzollern Trench was created 15 million years ago as a result of the tectonic tension caused by the folding of the Alps under the pressure of the African plate and the associated uplift of the Swabian Alb. The tremendous forces created cracks, crevices and ditches.

Relief reversal

Although it is an area of ​​incursion, the area inside the trench towers over its surroundings. This so-called relief reversal is particularly clear in the example of the Hohenzollern , where a height difference of up to 350 meters is reached. As a witness mountain, it owes its position and origin to the harder, more erosion-resistant rock types in the trench interior. On the Alb plateau, too, the hilly, wooded terrain in the course of the ditch stands out from the flatter, unwooded surroundings outside the ditch.

Connection with earthquakes

The Hohenzollerngraben as a tectonic fault was and is mistakenly commonly associated with an accumulation of earthquakes in the Zollernalb district. Since the beginning of the 20th century, three more powerful earthquakes have occurred in the Albstadt area :

date Magnitude Max. intensity epicenter
November 16, 1911 6.1 VIII Ebingen
May 28, 1943 5.6 VIII Space Tailfingen - Onstmettingen - Pfeffingen
3rd September 1978 5.7 VII-VIII Tailfingen

The event of 1911, one of the largest earthquakes in Germany in historical time, activated the quake zone around Albstadt. Since then, in addition to the earthquakes of 1943 and 1978, numerous other weaker tremors have occurred.

However, these earthquakes started from a weak zone , the so-called Albstadt shear zone , in the basement five to ten kilometers below the surface of the earth, while the Hohenzollerngraben, around two kilometers deep, is a structure close to the surface. The saline of the Middle Shell Limestone partially decouples the upper layers of the overburden from the deeper subsoil. The NNE – SSW -directed shear movements in the basement are expressed in stretch structures in the overburden that run approximately perpendicular to them. The structure of the Hohenzollern Trench is related to the shear zone without being the cause of the earthquake itself. Nevertheless, the Hohenzollern Trench is still mainly mentioned in the context of earthquake activities, which means that this linkage may have contributed significantly to its popularity among the population.

literature

  • John Reinecker, Götz Schneider: On the neotectonics of the Zollernalb: The Hohenzollerngraben and the Albstadt earthquake. In: Annual reports and communications from the Upper Rhine Geological Association. Vol. 84. 2002, ISSN  0078-2947 , pp. 391-417.

swell

  1. ↑ Gottfried Grünthal: Earthquakes and earthquake hazard in Germany and in the European context. In: Geography and School. No. 151, 2004, ISSN  0171-8649 , pp. 14-23, online (PDF; 3.27 MB) .
  2. ^ Otto F. Geyer , Manfred Gwinner , Matthias Geyer, Edgar Nitsch and Theo Simon : Geology of Baden-Württemberg. 5th completely revised edition, Schweizerbart, Stuttgart 2011, ISBN 978-3-510-65267-9 , p. 503

Coordinates: 48 ° 19 ′ 0 ″  N , 8 ° 58 ′ 30 ″  E