The impact of the earthquake activity in Western Europe from the historical and architectural heritage records - Intraplate Earthquakes - page 213

Heavy material fell down from high buildings, mainly from churches. An inventory of
the churches damaged by the earthquake has been compiled by consulting the newspapers
and testimonies sent to the Royal Observatory of Belgium at the time of the earthquake.
Thirty-two churches damaged by the 1938 earthquake have been identified in Belgium,
with damage states ranging from slight to moderate ( Figure 8.4 b ). This list is of course
not exhaustive. Indeed, when comparing the location of these churches with the areas
presenting the majority of damaged houses ( Figure 8.3 d ), they appear to be not exactly
identical. The damaged church area is slightly shifted to the north by comparison with the
damage region defined by the damaged classical low-rise buildings. The damaged church
zone actually corresponds to the quasi east-west region where the natural periods of soil
resonance are between 1 and 1.5 seconds, which are in agreement with the range of the
fundamental mode of oscillation of this type of large structure (Nguyen et al ., 2004 ) . To the
west of the epicentre, there appears to be a better overlap between the damage distributions
of churches and houses. This area corresponds to the valley of two large rivers, the Lys and
the Schelde-Escaut, and therefore to places assumed to present soil conditions less resistant
to seismic action.
The reports and eyewitness accounts from the newspapers about this earthquake can be
found via the link: http://seismologie.be/cup2014.html .

8.5.5 The 22 April 1884 Colchester earthquake

Despite its relatively lowestimatedmagnitude of aroundM , the Colchester earthquake

is considered to be the most damaging British earthquake in the last 400 years ( Figure 8.1 ) .
This event is very well documented due to the large number of local newspapers available
and also the existence of local amateur scientific societies at the end of the nineteenth
century. Musson et al .( 1990 ) provided a complete study of the earthquake, including most
of the reports written at the epoch of the earthquake and their associated sources. For
the purpose of our study, we have considered the Musson et al .( 1990 ) interpretation of the
damage provided by the scientific work of Meldola and White ( 1885 ) , the most prominent
study at the time of the earthquake. This information is reported in Figure 8.3 f .
Musson et al .( 1990 ) concluded that most of the damage in the epicentral area of this
earthquake ranged between EMS-98 damage grades 2 and 3. There is also evidence of
grade 4 damage associated with gaps in walls or the collapse of parts of buildings, but
they are rare and confined to buildings of the poorest districts. In fact, the importance and
the large geographical extent of the damage generated by the 1884 Colchester earthquake
appears relatively similar to those observed during the 1983 Liege earthquake in Belgium
(Figure 3c). On the other hand, unlike the Liege earthquake, the Colchester seismic event
caused moderate and extensive damage to churches in the epicentral area: the fall of parts
of towers, damage to roofs, and cracks in masonry and plaster.

= 4 ¾

8.5.6 The 23 February 1828 Hannut earthquake

We have revisited the 23 February 1828 earthquake that occurred in the central part of
Belgium ( Figure 8.1 ) , which was the first earthquake worldwide for which a scientist,