Geoscience Reference
In-Depth Information
2 Macroseismic Endeavors Before 1850
The first attempts to establish macroseismic intensity go back to Italy in the 17th
century. After the Capitanata earthquake of 1627, the Italian Matteo Greuter de-
signed an earthquake map in which damage was subdivided into four classes. It
was the large 1755 Lisbon earthquake however, which forged new methodologies
enhancing the study of earthquakes. The event, felt all over Europe as well as
Northern Africa, stimulated European intellectuals to produce hundreds of treatises
describing and analyzing the event (Braun and Radner 2005; Kozak et al. 2005;
Loffler 1999; Kendrick 1956) (Fig. 1). It is not easy to judge the degree to which
the Western European Enlightenment influenced and encouraged the scientific study
of the Lisbon earthquake, or - vice versa - how much the Lisbon earthquake and
the new approach to its analysis shaped the new studies of natural phenomena. Two
outstanding European naturalists turned their attention to the phenomenon of earth-
quakes, namely John Michell (1724-1793), Woodwardian professor of geology at
Cambridge, and Elie Bertrand (1713-1797), Swiss naturalist and geologist, pastor
at Berne and member of several Academies of Sciences. The latter composed and
published his famous treatise
Memoires historiques et physiques sur les tremble-
ments de terre
(Bertrand 1757), in which he presented a physical approach to the
movements of the earth. Both naturalists were later called founders of seismology
by Davison (1978). The analysis of natural events, and the principles of investiga-
tion set down after the 1755 Lisbon event and improved after the 1784 Calabria
earthquake, evolved and grew to the present; observing, measuring, collecting and
analyzing the data, building relations among the data and comparing them with other
known results and facts.
The procedure laid out by the 18th century naturalists was gradually improved
and refined in the course of the 19th century (we have to keep in mind that seis-
mology as a scientific geo-discipline did not exist prior to circa 1880; the first pro-
fessor of seismology was Seikel Sekiya (1834-1896) at the University of Tokyo in
1886; Emil Wiechert (1861-1928) was appointed professor of seismology at the
University of Gottingen as late as 1901). In this century most of the macroseismic
terminology was specified and labeled, their definition described and identified in
such terms as: epicenter, hypocenter, earthquake intensity, isoseismic lines, seismic
wave 'direction', velocity of seismic waves, etc. Not until the late 19th century were
seismic intensity scales, tectonic faults and individual types of seismic waves com-
monly measured, accepted and taken into consideration.
The use of cartographic tools to evaluate the distribution and degree of seismic
damage, known already since the early Mogiol seismic map of the 1564 Nice earth-
quake (Stucchi and Morelli 1992), improved considerably in the course of the 19th
century. Thematic cartography was a broadening field at the time (Robinson 1982),
and it was only reasonable that isoseismal mapping profited from this innovation
and adapted the methods of this discipline. Earthquake maps of this kind show how
macroseismic data was plotted onto suitable geographic maps as a helpful form to
describe the effects of an earthquake. The early earthquake maps eventually devel-
oped into the present maps of seismicity, which today represent an important tool in
earthquake engineering.
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