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| Titel |
The tsunami triggered by the 21 May 2003 Boumerdès-Zemmouri (Algeria) earthquake: field investigations on the French Mediterranean coast and tsunami modelling |
| VerfasserIn |
A. Sahal, J. Roger, S. Allgeyer, B. Lemaire, H. Hébert, F. Schindelé, F. Lavigne |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1561-8633
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| Digitales Dokument |
URL |
| Erschienen |
In: Natural Hazards and Earth System Science ; 9, no. 6 ; Nr. 9, no. 6 (2009-11-10), S.1823-1834 |
| Datensatznummer |
250007052
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| Publikation (Nr.) |
 copernicus.org/nhess-9-1823-2009.pdf |
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| Zusammenfassung |
A field survey was organized on the French Mediterranean coasts to
investigate the effects of the tsunami induced by the 21 May 2003
Boumerdès-Zemmouri (Algeria) earthquake (Mw=6.9). The results show
that eight harbours were affected by important sea level disturbances that
caused material loss. Unfortunately, the low sampling rate of the French tide
gage records (10 min) does not allow for a proper evaluation of the tsunami
wave amplitudes since these amplitudes were probably underestimated in the
harbours where these sensors are installed. The survey brings to light
regional and local contrasts among the harbours' hydrological responses to
the tsunami.
To better understand these contrasts, a numerical simulation of the sea level
elevations induced by the tsunami was conducted. The simulation showed a
certain correlation between the field results and the wave amplification
along the coast; however it underestimated the observed phenomena. Another
simulation was then conducted using high resolution bathymetric grids (space
step of 3 m) centred more specifically on 3 neighbouring harbours, however,
again the simulation results did not match the amplitudes recorded through
the observations. In order to better understand the wave amplification
mechanisms inside each grid, a Gaussian signal was virtually broadcasted from
the source to the harbours. Virtual sensors identified the periods which are
stimulated – or not – by the arrival of the signal in each grid. Comparing
these periods with those previously recorded emphasizes the proper period of
each waterbody.
This paper evaluates the limitations of such a study, focusing specifically
on (1) the importance of having accurate and precise data about the source
(the lack of information about the signal amplitude leads to an
underestimation of the tsunami, thus reproducing only a fourth to a third of
the observed phenomenon), (2) the need for networked tide gages with high
resolution records and short sampling rates, and (3) the importance of
conducting field studies immediately after a tsunami occurs. |
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