Geoscience Reference
In-Depth Information
(Stiros, 1996). Stiros (1996) has identified seven criteria for the recognition of
earthquake-induced structures. These are:
(1)
ancient constructions offset by seismic faults;
(2)
skeletons
of
people
killed
and
buried
under
the
debris
of
fallen
buildings;
(3)
certain abrupt geomorphological changes, occasionally associated with
destruction and/or abandonment of building sites;
(4)
characteristic structural damage and failure of constructions, including:
displaced drums of dry masonry columns,
opened
vertical
joints
and
horizontally
displaced
parts
of
dry
masonry walls,
diagonal cracks in rigid walls,
missing triangular sections of corners of masonry buildings,
cracks at the base or top of masonry columns and piers,
inclined or sub-vertical cracks in the upper parts of rigid arches,
vaults or domes, or their partial collapse along those cracks,
keystones that have slid downwards in dry masonry arches and
vaults,
several parallel fallen columns,
several fallen columns with their drums in a domino-style (imbri-
cated) arrangement,
constructions deformed by horizontal forces (rectangles deformed to
parallelograms);
(5)
destruction and quick reconstruction of sites with the introduction of
'anti-seismic' building construction techniques, but with no change in
their overall cultural character;
(6)
well-dated destruction of buildings correlating with historical (including
epigraphic) evidence of earthquakes; and
(7)
damage or destruction of isolated buildings or whole sites for which an
earthquake appears to be the only reasonable explanation.
It is important to be able to differentiate building damage due to earthquakes
from that caused by human actions during battles and wars. The above criteria
are designed to help in this differentiation and identify forms of evidence that
would be difficult to induce by human actions alone. For example, horizontal
forces or shaking are required to displace downwards a keystone in an arch. The
same is true of columns whose drums show offset in different directions and
particularly if those offset drums display a sinusoidal pattern along the length
of column. Figure 6.6 shows such offset drums in a column from the Heraion
Temple near Pythagorion on the island of Samos, Greece. The displaced columns
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