Archaeoseismology and Palaeoseismology in the Alpine ... - Tierra

Fig. 1: Series of aligned fallen columns (top: Susita, Golan
Heights; bottom: Knidos, Turkey), typical earthquake‐
characteristic damage?
PRESENT: AN ARCHAEOSEISMOLOGICAL PERSPECTIVE
Archaeoseismology is plagued by many of the same
ambiguities that geologists encounter when interpreting
earthquake indicators in the landscape or in
palaeoseismological trenches. All are prone to naturally
disruptive processes that can mimic the expression of
seismic rupture or shaking. But cultural material data bear
the additional vagaries of uncertain human action, from
the questionable quality of construction to the potential
for manmade destruction. The result is that it is difficult –
if not impossible – to irrefutably distinguish between
damage caused by man or competing natural agents.
Typologies of earthquake‐characteristic damage (Fig. 1)
have been proposed but when subjected to critical
appraisal – in particular through numerical and analogue
modelling (e.g. Hinzen et al., 2009) – most of these
typologies do not pass the test. Even if they could, it
remains uncertain how the seismic traces in destruction
layers and dislocated buildings can be meaningfully
translated into earthquake parameters such as intensity,
peak ground acceleration, etc.
To overcome these uncertainties, conceptual – primarily
qualitative – archaeoseismological schemes have been
1 st INQUA‐IGCP‐567 International Workshop on Earthquake Archeology and Paleoseismology
144
proposed, consisting of a list of points of interest (Karcz
and Kafri, 1978, Nikonov, 1988, Rapp, 1986, Stiros, 1996),
key research questions (Guidoboni, 1996), or flow charts
(Galadini et al., 2006) that ought to be considered during
the investigation of an archaeological site by collaborative
teams of seismologists, geologists, archaeologists,
architects and historians. Most of these schemes have
been grafted onto archaeological investigations in the
eastern Mediterranean and in the Middle East, with
strong dependence on identifying structural damage to
buildings and other cultural remains at specific sites.
A more quantitative scheme has been proposed by
Hinzen (2005) in the form of a feasibility matrix for
archaeoseismological findings that evaluates a probability
of occurrence of a proposed ancient earthquake and that
can be directly used as a weighting factor in probabilistic‐
based estimations of the seismic hazard. Sintubin and
Stewart (2008) integrated the competing schemes into a
standardised, semiquantitative logic‐tree formalism for
archaeoseismology, assessing the level of certainty to
which an archaeological site has recorded an ancient
earthquake.
In spite of all these efforts and given the all too obvious
limitations and constraints of the archaeological record,
perhaps it is timely to reconsider what archaeoseismology
is all about. Can we legitimately claim that it is a potential
contributor to probabilistic seismic hazard studies? Or
does the true value of archaeoseismological research lie
elsewhere?
Archaeological sites may have a potentially unique value
in earthquake science. Rather than simply augmenting
earthquake catalogues with – potentially highly
conjectural – ancient earthquakes, ancient archaeological
sites can be used strategically to examine specific
earthquake scenarios. Key targets could be those major
events that appear form historical accounts to be
atypically destructive, but whose excessive reach and
intensity warrant careful appraisal, e.g., events such as
the A.D. 21 July 365 Crete earthquake and tsunami. In this
context, archaeological sites become “seismoscopes” –
the testing ground for predicted site effects of ancient
earthquake models.
FUTURE: A SOCIOLOGICAL PERSPECTIVE?
But maybe the scope and goals of archaeoseismological
studies should still be broadened, benefiting from more
intimate collaborations between earthquake geologists
and archaeologists in deciphering the precise role of
earthquakes in the cultural history of a site. A better
appreciation of the complex dynamics by which ancient
cultures dealt with and responded to damaging
earthquakes, might shed light on the resilience of past
societies and their relative capacity to withstand seismic
shocks.
By highlighting how their ancestors coped with
earthquakes, archaeoseismology could play a key role in
fostering better earthquake preparedness in modern local
communities that are equally threatened. After all,
natural disasters are no physical phenomena, but are
social phenomena (Shimoyama 2002). Rather than simply
deriving crude parameters for ancient earthquakes,