How Historical Seismology Can Benefit from Bureaucracy: The Case of the “Lettere Patenti” in the City of Rome in 1703

The 1703Mw 6.9 seismic sequence (I0 11 Mercalli–Cancani–Sieberg scale) was one of the
most important crises ever occurred in Italy and has left a deep mark on the seismic
history of cities and towns of central Italy. Abundant documents testify the damage
suffered by the city of Rome during this sequence; however, the descriptions are mainly
referred to monumental buildings. For the recent macroseismic practice, such edifices
are not statistically representative when used for assessing macroseismic intensity;
instead, the information about residential housing provides reliable data especially
when using the European Macroseismic Scale 1998. In this work, we show that useful
information regarding the ordinary residential stock can be retrieved in the bureaucratic
documentation, apparently distant from the repertoires traditionally used for historical
seismology studies. In particular, we used administrative acts granted by the government
of Rome to authorize maintenance works on the external parts of the buildings,
namely the “Lettere Patenti.” The scrutiny of these sources allowed us to enrich the
available dataset introducing 93 new damage points found on civil building stock
spread in the historic center of Rome. The new dataset contributes to better define
the picture of the effects of the 1703 seismic sequence in Rome, which allowed us
to assess macroseismic intensity with more confidence.