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About Earthquakes | Rescent Earthquakes
Earthquake Turkey 06-02-2023
On February 6, 2023, a major earthquake of magnitude 7.8 occurred in the Turkish-Syrian border region, followed about 9 hours later by a second earthquake of magnitude 7.5.
Both earthquakes involved a rupture about 300 km long, with the first in a southwest-northeast direction and the second having a west-east orientation. The second earthquake was triggered by the first one due to stress rearrangements. In this southern displacement zone of the Anatolian plate, the two earthquakes released stresses that had been building up for probably more than 100 years.
The first earthquake waves (so-called P-waves) reached the Göttingen earthquake stations GTT (historical Wiechert seismographs) and GTTG (modern STS-2 broadband seismometer) 2600 km away after (5 min + 18 s). The larger S waves followed about 4.5 min later, and surface waves arrived in Göttingen shortly thereafter.
A comparison of the Göttingen registrations again shows the high quality of the historical Wiechert seismographs. The displacement transducers, which have been working with mechanical amplification for 120 years in some cases, can definitely keep up with the modern mechatronic devices.
By a great coincidence, the horizontal ground motions caused by an earthquake more than 2500 km away could be impressively filmed for the first time in Göttingen.
This was achieved by purely mechanical amplification of the movements by a factor of about 200 by Emil Wiechert’s astatic horizontal seismograph, which has been in continuous use in Göttingen for 120 years.
In this case, the recording needles of the two horizontal components did not lie on sooty paper but lifted off on a Teflon-coated wire. This allowed them to migrate beyond the edges of the sooted paper (as was observed in the further course) and thus saved the registration with the laser system. Otherwise, the writing needles would have been torn out of their bearings when they hit the boundaries of the paper strips and thus also the laser mirrors attached to the writing arms would have been knocked over.