Geoscience Reference
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8.5.7 The 18 September 1692 Verviers earthquake
The earthquake of 18 September 1692 is probably the largest known earthquake that has
occurred in Western Europe north of the Alps ( Figure 8.1 ) . Recent investigations based
on original reports of the effects produced by this earthquake suggest that its source was
located in the region of Verviers in the northern part of the Belgian Ardenne and that its
magnitude may have reached 6
¼
(Alexandre and Kupper, 1997 ; Camelbeeck et al ., 2000 ;
Alexandre et al ., 2005 , 2008).
In the epicentral area, substantial to heavy damage and sometimes complete destruction
are described for large buildings (castles and churches) and for houses. The ground shaking
also appears to have been violently felt by the people (Alexandre et al ., 2008 ) . For the most
affected villages ( Figure 8.5 B ) (e.g., Herve, Ensival, Soiron, Walhorn), the reports mention
that some houses were ruined, with the consequence that inhabitants were injured or killed.
This suggests that some buildings presented complete damage (EMS-98 grade 4 to 5) in
the earthquake epicentral area. Considering that the most affected houses had vulnerability
class A, “few” buildings presenting damage of grade 4 would correspond to intensity VII,
whereas “few” buildings with damage of grade 5 would suggest intensity VIII. The latter is
in agreement with Alexandre et al .( 2008 ) , who propose that the intensity reached VIII in
these localities. Outside the epicentral area, one characteristic of the 1692 earthquake is the
significant spatial extension of the damage to large buildings of the architectural heritage
in Belgium, France, Germany, and southeastern England ( Figure 8.4 d ).
The original reports of the witnesses and the description of the historical sources are
available at http://seismologie.be/cup2014.html .
As usual for historical earthquakes, the accounts of the damage caused by the 1692
earthquake are poor from a quantitative point of view, which renders intensity evaluation
uncertain. Soiron, one of the more damaged localities, is a village presenting a structure that
has stayed unchanged since the eighteenth century. We took this as an opportunity to study
the existing building stock in the centre of the village that dated from the seventeenth and
the beginning of the eighteenth century to find complementary arguments to the historical
data that may help to evaluate the earthquake intensity in this village (Dewattines, 2010 ) .
Two historical sources describe the effects of the earthquake in Soiron. The priest wrote
in his notes: “A horrible earthquake that brought down houses, chimneys . . . ” (Servais
Ronval, Notes ). A second historical source written by the lord of Soiron depicted the very
heavy structural damage caused to the castle. The structure of the church also was heavily
damaged and, with the exception of its tower, a new church was built from 1723 to 1727 due
to the consequences of this earthquake.
Figure 8.7 A shows a map of the centre of Soiron with the houses that retain a complete
or partial structure dating from the seventeenth century. There are about 36 such build-
ings. Most of these houses were partly or totally reconstructed after the 1692 earthquake
(11 buildings, 30.5%) or show repairs or pathologies that could be attributed to this earth-
quake (14 buildings, 39%). During the eighteenth century, some houses were transformed
(11 buildings, 30.5%) ( Figure 8.7 B ). These buildings are included in the basic structure
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