Since the end of August once in a while the earth judders in Posterstein Region. The nearest seismometer station in Heukewalde, driven by Jena University, noted light earthquake swarms in that time. In the so-called Vogtland region and parts of West Saxony quakes measuring 4.0 on the Richter magnitude scale were documented (see: Ostthüringer Zeitung). You can have a look at the latest seismometer graphs on the university’s web page, where you can search after the station with the name HKWD (Heukewalde)
Seismometer graph from the station in Heukewalde, September 4th 2011
Why does the earth shake?
The earth is divided in different tectonic plates. Especially on the borders of a plate, where two plates are pushing against each other, heavy earthquakes can occur. But Posterstein region lies far away from the borders of the Eurasian plate. Responsible for the mostly harmless so-called intra plate quakes, that happen once in a while, is pressure on the Eurasian plate from West and South. In the Vogtland region there are many smaller blocks and cracks that also earlier in the history have led to lighter earthquake swarms. Today the Seismic network of Thuringia monitors and scientifically explores the region. Earlier there was a seismometer installed in the cellar of Posterstein castle as well, but as vibrations caused by the castle’s visitors climbing on the tower distorted the measuring, the station was moved to near-by Heukewalde.
The Middle-European earthquake of 1872
The heaviest earthquake in the region was registered on March 6th 1872 – its centre lay between Posterstein and Schmölln. Karl Theordor Liebe (1828-1894), professor at the Princely Grammar School in Gera, was reporting on the earthquake’s impacts in Posterstein. Among others, he writes that the castle’s tower was shaking and bigger rocks came rolling down the hill. At that time deep cracks occurred in the three metre thick wall of the tower and in the walls of the castle’s bridge:
Crack in the castle's bridge before the restoration (picture from 1985, Museum Burg Posterstein)
„On the old castle we have seen a lot of new cracks, which took there way through grout and stone. In the cellar of the old castle came so much material off the ceiling that more than a 100 litres of milk became useless. The new castle (manor house), which is standing next to the old castle, has 1.2 metre thick walls and in the first floor 0.9 metre thick walls. But there doesn’t exist a single room without cracks in the walls and ceiling”, wrote Karl Theodor Liebe.
The crack in the bridge was repaired during the restoration in 1997, but you still can see the crack in the tower on your way to the top of the tower.
Contemporary witnesses report
Crack in the castle's tower's wall
The teacher and historian Ernst Bräunlich from Posterstein recorded the memories of the pastor Johann Michael Nürnberger from Nöbdenitz, who had witnessed the 1872 earthquake himself: „In the village people came running out of their houses from all ways and they told that they were hasty leaving their houses in fear. The trees had been shaking and on the road they had heard a ratting as if 6 or 8 wagons with heavy load passed by in trot. In the village seven chimneys collapsed. The incidence was the main topic of conversation in a long time.”
The light quake from September 4th 2011 was noted by locals, too. The heaviest vibration could be observed between 4 and 5 in the morning. On our Facebook wall a witness wrote that she woke up because of the chattering in the sleeping room.
Seismometer in Posterstein
In the castle’s permanent exhibition you can have a look at a seismometer and read more about earthquakes in the Posterstein region – more information on www.burg-posterstein.de.
(Text: Marlene Hofmann)