Earthquakes in Saxony (Germany) and surroundings from 2006 up to 2023 -- onsets and locations

Author: Siegfried Wendt

This archive contains complete results of earthquake locations for Saxony (Germany) and surrounding areas in Czech 
Republic for the years 2006 to 2023. Approximately 26.000 events were detected and localized, most of them with 
epicenters in Northwestern Bohemia close to the Saxon border.

Analysis was done at Collm observatory of Leipzig University by Siegfried Wendt using software SEISAN (Earthquake 
analaysis software [1] from University of Bergen, Norway). Results contain all used picks and amplitudes of the 
stations. Results are written in NORDIC format [2] as ASCII files.

Used waveform data comes from different local and regional seismic networks: SX -- SXNET Saxon Seismic Network [3], 
WB -- West Bohemia Local Seismic Network [4], TH -- Thüringer Seismologisches Netz [5], BW -- BayernNetz [6], CZ -- 
Czech Regional Seismic Network [7], GR -- German Regional Seismic Network [8]. Sampling rates differ among the 
networks and are either 100 or 200 samples per second (sps). The sensors have various eigenfrequencies: short 
period (1 second), middle period (5 seconds, majority in Saxony) and broad band (30 seconds and more). Number of 
available stations increased over time from 20 in 2006 up to 50 in 2023. Waveform data from local German networks 
SX and TH are publicly available from the datacenter of the German Regional Seismic Network [9]. Some of the 
seismograms of neighbouring seismic networks aren't publicly available; for details please directly contact the 
networks.

Seismological background: In Northwestern Bohemia (Czech Republic) and Vogtland (Saxony, Thuringia, Bavaria in 
Germany) there is an isolated region with remarkable natural seismicity. The noun Schwarmbeben, i.e. "swarm 
[earth]quake" was introduced by Credner (1898) [10] and Knett (1899) [11] related to local earthquake sequences of 
the Vogtland/Northwestern Bohemia region. The seismological active zone stretches northward for more than 150 km 
up to the region of the cities Halle/Saale and Leipzig (Germany).

Some details to used NORDIC format [2] -- type 1 line: Character 21 (Location model indicator) shows the local 
velocity model used for localization the events. Empty field relates to standard model file model.txt, the 
characters "a", "h", "M", "q", "w" and "z" refer to different models (all attended). Velocities Vp of the single 
layers are constant. In every case the Vp/Vs ratio is 1.74.
-- type 4 line: Characters 11-14 (Phase ID) show in case of amplitudes "IAML". This means local "Wood-Anderson 
amplitudes in nm" related to description by IASPEI to compute local magnitude "ML".
-- type 4 line: Characters 34-40 (Amplitude): The values are related to Zero-Peak (Wood-Anderson) amplitudes in 
nm; in praxi measured as Peak-to-Peak divided by 2. During Wood-Anderson simulation a bandpass filter 1.25 to 
20.0 Hz is applied to the waveforms.
-- type 4 line: Characters 42-45 (Period Seconds): Providing this values is a kind of extension of definition of 
local magnitudes. It helps to restore true ground motion.

[1] Havskov, J., Voss, P.H. and Ottemoller, L. (2020). Seismological Observatory Software: 30 Yr of SEISAN. 
Seismological Research Letters, 91 (3): 1846-1852. DOI: https://doi.org/10.1785/0220190313
[2] https://seisan.info/v13/node259.html: A. The Nordic format - SEISAN
[3] https://doi.org/10.7914/SN/SX
[4] https://doi.org/10.7914/SN/WB
[5] https://doi.org/10.7914/SN/TH
[6] https://doi.org/10.7914/SN/WB
[7] https://doi.org/10.7914/SN/CZ
[8] https://doi.org/10.25928/mbx6-hr74
[9] https://www.fdsn.org/datacenters/detail/BGR/
[10] Credner, Hermann, 1898. Die sächsischen Erdbeben während der Jahre 1889 bis 1897, insbesondere das sächsisch-
böhmische Erdbeben vom 24. October bis 29. November 1897. Abhandlungen der Mathematisch-Physischen Klasse der 
Königlich-Sächsischen Gesellschaft der Wissenschaften; 24,4; http://digital.slub-dresden.de/id302694390
[11] Knett 1899. Das erzgebirgische Schwarmbeben zu Hartenberg vom 1. Jänner bis 5. Feber 1824. Sitzungsber. 
Deutsch. Naturwiss.-Med. Ver. Böhmen (in German). 19: 167–191.
