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Information - TS21 Paleoseismology and active tectonics of the Alps (co-listed in SM) (co-sponsored by INQUA)
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Event Information |
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On November 24, 2004, a moderate earthquake (Ml 5.2, Mw 5.0;
focal depth 8 km; source INGV) hit the Lake Garda region, within
the active fold and thrust belt of the Southern Alps.
This earthquake was strongly felt in the whole Northern
Italy, from Venice to Milan and Genoa, and abroad, for instance in
Switzerland; the epicentral area includes the town of Salò and its
surroundings, where significant damage occurred and more than
200 people were left homeless. This event occurred in a well-known
seismic area, hit by a similar earthquake in 1901. Since the
Alpine region includes some of the most densely populated and
economically developed, and therefore exposed to seismic risks,
areas of the whole Europe, even moderate events like this can cause
heavy societal impact, if not adequately foreseen. In fact, earthquakes
much greater than this can be expected in Northern Italy and bordering
countries.
Earthquake fault plane solutions, seismic sections and geomorphic
studies indicate that the active tectonics of the Alps is
dominated by folding and thrusting. However, in several areas around
this mountain belt, the kinematics of present-day deformation
and its relationship with the seismicity are indeed not well understood.
In some cases, geological research conducted in the past decade has
shown apparent disagreement between historical/instrumental
seismicity information and paleoseismological data.
For instance, paleoseismological and active tectonics studies indicate
that in the western Southern Alps, Central Switzerland,
and SW France, the seismicity level, in terms of maximum potential
earthquakes and their average return periods, could be quite different
from that illustrated by the seismic catalogues.
Careful analysis of fossil earthquake ground effects including surface
faulting, liquefaction, deformation of lake sediments and lake shores, rockfalls,
displaced speleothems and other effects on karst features, now available
at a number of sites in the Alps, demonstrate that the geological evidence
should be taken much more carefully into account before drawing conclusions on
the seismic potential of the Alpine Chain and related piedmont belts.
Clearly, a cross-disciplinary, international approach is required, and it is
therefore timely - in fact, largely overdue.... - to bring together a broad range of expertise to discuss the problem of seismic hazard assessment in the Alps based on geological data.
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Preliminary List of Solicited Speakers |
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