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New paper!“The 23 February 1828 Belgian earthquake: a destructive moderate event typical of the seismic activity in Western Europe”
by Thierry Camelbeeck, E. Knuts, P. Alexandre, @seismotom and @Koen_VanNoten. Link: https://rdcu.be/cexlf . #springerlink. A thread [1/16]:
![New paper!“The 23 February 1828 Belgian earthquake: a destructive moderate event typical of the seismic activity in Western Europe” by Thierry Camelbeeck, E. Knuts, P. Alexandre, @seismotom and @Koen_VanNoten. Link: https://rdcu.be/cexlf . #springerlink. A thread [1/16]:](https://pbs.twimg.com/media/EtTp3qSXEAAHMBJ.jpg "New paper!“The 23 February 1828 Belgian earthquake: a destructive moderate event typical of the seismic activity in Western Europe” by Thierry Camelbeeck, E. Knuts, P. Alexandre, @seismotom and @Koen_VanNoten. Link: https://rdcu.be/cexlf . #springerlink. A thread [1/16]:")
This earthquake happened in central Belgium (i.e. the Low Countries at that time) and is one of rare severely damaging seismic events that occurred during the last two centuries in West Europe in the region extending from the Lower Rhine Embayment to the North Sea. [2/16]
![This earthquake happened in central Belgium (i.e. the Low Countries at that time) and is one of rare severely damaging seismic events that occurred during the last two centuries in West Europe in the region extending from the Lower Rhine Embayment to the North Sea. [2/16]](https://pbs.twimg.com/media/EtTqOZPXEAAZ5hW.jpg "This earthquake happened in central Belgium (i.e. the Low Countries at that time) and is one of rare severely damaging seismic events that occurred during the last two centuries in West Europe in the region extending from the Lower Rhine Embayment to the North Sea. [2/16]")
Priest P. Lamarche: “Sat. 23 Feb. 1828, 8h30: I sang the mass in Lens-Saint-Servais. Suddenly the earth shakes violently. We all escape from church while the arch cracks in two, altar bunches flip, candlesticks fall. Outside, chimneys are falling… It lasted 8 seconds.” [3/16]
In his letter, the Burgomaster of Grand Hallet asks funds to the District Head of Waremme to repair the church of Grand Hallet. The details in his letter are remarkable. [4/16]
![In his letter, the Burgomaster of Grand Hallet asks funds to the District Head of Waremme to repair the church of Grand Hallet. The details in his letter are remarkable. [4/16]](https://pbs.twimg.com/media/EtTqe5TXUAQrkDs.jpg "In his letter, the Burgomaster of Grand Hallet asks funds to the District Head of Waremme to repair the church of Grand Hallet. The details in his letter are remarkable. [4/16]")
These personal reports tell us how severely the 1828 earthquake was felt and what damage it caused. We reconstructed the earthquake's impact by evaluating historical sources and surveying newspapers, scientific studies, and official, private and religious historical texts. [5/16]
Many churches in the 1828 epicentral area in the Hesbaye region in Belgium were damaged and afterwards repaired. Check the 1831 repair sign in cramp irons on top of the church in Marilles on Google Earth: [6/16]
https://www.google.com/maps/@50.7074665,4.9524465,3a,75y,64.71h,101.81t/data=!3m6!1e1!3m4!1srlezNSYD_5SP5CorWqcSvg!2e0!7i13312!8i6656
![Many churches in the 1828 epicentral area in the Hesbaye region in Belgium were damaged and afterwards repaired. Check the 1831 repair sign in cramp irons on top of the church in Marilles on Google Earth: [6/16] https://www.google.com/maps/@50.7074665,4.9524465,3a,75y,64.71h,101.81t/data=!3m6!1e1!3m4!1srlezNSYD_5SP5CorWqcSvg!2e0!7i13312!8i6656](https://pbs.twimg.com/media/EtTq8SxXAAMcc_V.jpg "Many churches in the 1828 epicentral area in the Hesbaye region in Belgium were damaged and afterwards repaired. Check the 1831 repair sign in cramp irons on top of the church in Marilles on Google Earth: [6/16] https://www.google.com/maps/@50.7074665,4.9524465,3a,75y,64.71h,101.81t/data=!3m6!1e1!3m4!1srlezNSYD_5SP5CorWqcSvg!2e0!7i13312!8i6656")
https://www.google.com/maps/@50.7074665,4.9524465,3a,75y,64.71h,101.81t/data=!3m6!1e1!3m4!1srlezNSYD_5SP5CorWqcSvg!2e0!7i13312!8i6656
In 1828, the Prussian scientist Egen was the first scientist worldwide to present the severity of shaking in a macroseismic map using an intensity scale (going from yellow to blue to red). Egen's map of the 1828 earthquake is unique. [7/16]
![In 1828, the Prussian scientist Egen was the first scientist worldwide to present the severity of shaking in a macroseismic map using an intensity scale (going from yellow to blue to red). Egen's map of the 1828 earthquake is unique. [7/16]](https://pbs.twimg.com/media/EtTrCJ8XUAIjT2p.jpg "In 1828, the Prussian scientist Egen was the first scientist worldwide to present the severity of shaking in a macroseismic map using an intensity scale (going from yellow to blue to red). Egen's map of the 1828 earthquake is unique. [7/16]")
By consulting 225 historical sources, we collected macroseismic intensity data points for 185 localities in the present territory of Belgium, France, Germany, The Netherlands, Grand Duchy of Luxembourg, and southern England. This shows how widely this event was perceived. [8/16]
![By consulting 225 historical sources, we collected macroseismic intensity data points for 185 localities in the present territory of Belgium, France, Germany, The Netherlands, Grand Duchy of Luxembourg, and southern England. This shows how widely this event was perceived. [8/16]](https://pbs.twimg.com/media/EtTrH-tXcAUGy80.jpg "By consulting 225 historical sources, we collected macroseismic intensity data points for 185 localities in the present territory of Belgium, France, Germany, The Netherlands, Grand Duchy of Luxembourg, and southern England. This shows how widely this event was perceived. [8/16]")
Using historical sources, we re-evaluated for 141 localities the EMS-98 macroseismic intensity, i.e. a measure describing the severity of shaking at the surface. In the epicentral area, maximum intensity of VII was determined. [9/16]
![Using historical sources, we re-evaluated for 141 localities the EMS-98 macroseismic intensity, i.e. a measure describing the severity of shaking at the surface. In the epicentral area, maximum intensity of VII was determined. [9/16]](https://pbs.twimg.com/media/EtTrVCVWQAE9o_X.jpg "Using historical sources, we re-evaluated for 141 localities the EMS-98 macroseismic intensity, i.e. a measure describing the severity of shaking at the surface. In the epicentral area, maximum intensity of VII was determined. [9/16]")
The 23 February 1828 earthquake severely damaged houses and churches but also caused significant environmental effects, such as deviating water flows, appearing springs and springs drying up. [10/16]
![The 23 February 1828 earthquake severely damaged houses and churches but also caused significant environmental effects, such as deviating water flows, appearing springs and springs drying up. [10/16]](https://pbs.twimg.com/media/EtTrkmJXYAQDn8Y.jpg "The 23 February 1828 earthquake severely damaged houses and churches but also caused significant environmental effects, such as deviating water flows, appearing springs and springs drying up. [10/16]")
Using the intensity data, the epicenter was re-evaluated to 50.70°N and 5.12°N, with an uncertainty of ~10 km. Magnitude was estimated at Mw=5.1 ± 0.3 and focal depth placed at 10 km with uncertainty between 3 and 15 km. [11/16]
To understand the intensity repartition, @seismotom and @Koen_VanNoten digitised the analogue Belgian population density catalogue of Rogier (1849) using @QGIS and @googleearth. This kept them busy during the first week of the lockdown in March 2020 [12/16]
![To understand the intensity repartition, @seismotom and @Koen_VanNoten digitised the analogue Belgian population density catalogue of Rogier (1849) using @QGIS and @googleearth. This kept them busy during the first week of the lockdown in March 2020 [12/16]](https://pbs.twimg.com/media/EtTr0KqXYAEkjKq.jpg "To understand the intensity repartition, @seismotom and @Koen_VanNoten digitised the analogue Belgian population density catalogue of Rogier (1849) using @QGIS and @googleearth. This kept them busy during the first week of the lockdown in March 2020 [12/16]")
Population density, geological context, and historical source type determine the intensity spatial distribution. The 1828 shaking strength diminished more slowly along the WSW-ENE strike of the Brabant Massif compared to the surrounding Rhenish Massif and Paris Basin. [13/16]
Our study illustrates the benefit of historical seismicity studies on the knowledge of the impact of rare destructive earthquakes in stable continental regions like Western Europe. It also shows the importance historians have in improving a country’s seismic catalogue [14/16]
All intensity data and original historical texts are available in supplement to the paper here: https://www.readcube.com/articles/supplement?doi=10.1007%2Fs10950-020-09977-6&index=0
or on our website: http://seismologie.be/cup2014.html#/macro-event/383
The list allows you to evaluate the intensity decay with distance yourself. [15/16]
![All intensity data and original historical texts are available in supplement to the paper here: https://www.readcube.com/articles/supplement?doi=10.1007%2Fs10950-020-09977-6&index=0or on our website: http://seismologie.be/cup2014.html#/macro-event/383The list allows you to evaluate the intensity decay with distance yourself. [15/16]](https://pbs.twimg.com/media/EtTsAn5WYAEuCL-.jpg "All intensity data and original historical texts are available in supplement to the paper here: https://www.readcube.com/articles/supplement?doi=10.1007%2Fs10950-020-09977-6&index=0or on our website: http://seismologie.be/cup2014.html#/macro-event/383The list allows you to evaluate the intensity decay with distance yourself. [15/16]")
or on our website: http://seismologie.be/cup2014.html#/macro-event/383
The list allows you to evaluate the intensity decay with distance yourself. [15/16]
Finally, we thank @Belspo and @ORB_KSB for financial support of this study. Figures were created using @qgis and data was plotted using @matplotlib. End of thread [16/16].
