Is a major earthquake, like the one in Morocco last Friday, also possible in Belgium? The chance is very small, but not non-existent, says seismologist Koen Van Noten. "There are a lot of fault lines in our subsoil and these triggered earthquakes and damage during last century."
The worst earthquake in Belgium, dates back to 1692, some 300 years ago. "The epicentre was in Verviers (Liege Province). The strength of the earthquake was estimated at 6.5, which is quite severe," says seismologist Koen Van Noten.
"It is generally believed that the probability of a major earthquake only occurs once every 300 years. But that is based on only two recorded cases, from the 14th century, and the 17th century," says Van Noten. So there is certainly no long, documented history of earthquakes in Belgium on which to make statistical assumptions, the seismologist notes.
The earthquake in Verviers (1692) is the biggest quake documented here, but the twentieth century also saw a series of earthquakes that also claimed victims. "In Zulzeke, near Oudenaarde (East Flanders), an earthquake with a magnitude of 5.8 was measured in 1938. In 1983, a quake with a magnitude of 5.1 was measured in Liège. The most recent major earthquake dates from 1992 in Roermond, just across the border in the Netherlands. It was felt all over Belgium. It had a magnitude of 5.8."
Statistical predictions
Predicting earthquakes is unfortunately still not possible, says Van Noten. "The earthquake is recorded the moment it occurs. Knowing in advance that an earthquake is going to happen next week is impossible," he says.
But history does tell us that we are on ground that is slightly active. By keeping data and using seismometers, which are sensitive measuring instruments, one can see which regions are more earthquake-prone than others and with which frequencies quakes occur there. In this way, one can statistically calculate but not predict the probability of earthquakes, Van Noten explains.
"Our instruments are relatively new. We have only been able to measure earthquakes for the past 100 years. As a result, we still lack enough information to make informed statistical predictions."
25 seismometers in Belgium
At the seismology department of the Royal Observatory of Belgium, Van Noten carries out research into earthquakes in our country. "In Belgium, there are now some 25 seismometers that we maintain at the Observatory. We also try to complete our catalogue of earthquakes using historical texts and the geological history of our subsurface."
Basically, wherever there are fault lines, the possibility of an earthquake is real. In Belgium, these fault lines are mainly in the east of our country, against the border with the Netherlands, and in the Ardennes, around the region of Verviers and Liège, Van Noten explains. "The fault lines in the eastern Limburg region are active. Every few weeks or months an earthquake takes place there, but they are not felt," Van Noten immediately reassures us.
The Royal Observatory of Belgium's website systematically tracks earthquakes in our country. The most recent earthquake was on 26 August. 'That was in Francorchamps, in the province of Liège. That quake only had a magnitude of 1.5 and was not felt,' says Van Noten.