The impact of the earthquake activity in Western Europe from the historical and architectural heritage records - Intraplate Earthquakes - page 203

seismic instruments and, second, there are far fewer scientific studies and less documen-
tation describing their effects and damage. Hence, their investigation requires collecting
accounts and eyewitness reports in different types of historical sources. Often, the most
interesting sources are the individual narratives found in diaries, letters, and brief notes.
Local chronicles and annotations in parish registers generally mention the seismic events,
but often without detailed information. In fact, there is more chance of finding quantitative
data on the damage in administrative sources, including reports from local authorities,
account topics indicating repair costs, or official civil or ecclesiastic reports asking for
funds to repair damaged buildings or churches. Reports written some decades later can
also include relevant information on the damage produced by an earthquake as indirect
first-hand sources transmitted to us as second-hand sources. Newspapers and other period-
ical contemporaneous publications are another common source of information, after their
origins during the seventeenth century in Western Europe (Alexandre et al ., 2007 ) .
In essence, all the historical reports are incomplete in the sense that they provide very little
quantitative information on earthquake effects and, for a given earthquake, the geographical
distribution of the localities for which they provide information often is not homogeneous.
To improve our knowledge of the impact of historical earthquakes, it is thus necessary
to collect more eyewitness accounts in record offices, in order to better characterize local
damage and geographically extend our knowledge of earthquake effects.
Another way to better characterize the damage caused by past earthquakes is to look
for repairs or weaknesses in present-day buildings that already existed at the epoch of
the earthquake, in order to evaluate whether these disturbances can be explained by an
earthquake. Such evidence is complementary to the historical reports and is an invaluable
source of information on the destructiveness of past earthquakes, as will be shown in this
chapter. Large buildings such as churches or castles appear to be the most appropriate
structures for which to investigate such relationships, even if they are not the most adequate
for evaluating intensity (Grunthal et al ., 1998 ) . Indeed, these buildings more easily
survive the effects of aging than individual houses. Moreover, the construction and mainte-
nance data for these buildings are generally noted in the archives of the local parish or local
administration. Hence, there is more chance of retrieving information on their different
phases of construction or reconstruction than for particular houses.
Establishing a link between an earthquake and possible damage to a specific building
from observed pathologies or (and) repair traces needs a strict methodological approach.
The first aspect to consider concerns the estimation of the age of the buildings and the
dating of repairs and existing pathologies. Second, pathologies and repairs can result
from numerous different causes other than the earthquake hypothesis. Therefore, it is
necessary to confront the observations with the different possible hypotheses and to accept
the earthquake origin only if sufficient scientific arguments can be given. A beautiful
example in archeoseismology illustrating the importance of such detailed investigation,
including numerical modelling, is given by the study by Hinzen et al .( 2010 ) on the Lycian
sarcophagus of Arttumpara in Turkey, which deciphered human and earthquake actions on
the sarcophagus.