nom_organisme nom_organisme nom_organisme nom_organisme
Mar 20, 2017
Extreme storms during the last 6500 ys from lagoonal sedimentary archives in the Mar Menor (SE Spain)

Fig. 1. Grain  size  population  from  the  Mar  Menor MM2 record with clay (< 2 μm), silt (> 2 and < 63 μm), and sand fraction (> 63 μm). Shaded areas mark the main variations of the sand fraction


 


 

Storms and tsunamis, which may seriously endanger human society, are amongst the most devastating marine catastrophes that can occur in coastal areas. Many such events are known and have been reported for the Mediterranean. In a sediment core from the Mar Menor (SE Spain), we discovered eight coarse-grained layers which document marine incursions during periods of intense storm activity or tsunami events. Based on  radiocarbon dating, these extreme events occurred around 5250, 4000,  3600,  3010,  2300,  1350,  650,  and  80  years  cal BP. No comparable events have been observed during the 20thand 21st centuries. The results  indicate  little  likelihood  of a  tsunami  origin  for  these  coarse-grained  layers,  although historical tsunami events are recorded in this region. These periods  of  surge  events  seem  to  coincide  with  the  coldest periods  in  Europe  during  the late Holocene,  suggesting  a control by a  climatic mechanism  for periods of increased storm activity. Spectral analyses performed on the sand percentage revealed 4 major periodicities of 1228±327, 732±80, 562 ±58 and 319±16 years. Amongst the well -known proxies that have revealed a millennial-scale climate variability during the Holocene, the ice-rafted debris (IRD) indices in the North Atlantic developed by Bond et al. (1997, 2001) present a cyclicity of 1470±500 years, which matches the 1228±327-year periodicity evi-denced in the Mar Menor, considering the respective uncertainties in the periodicities. Thus,  an  in-phase  storm  activity  in  the  western  Mediterranean  is  found  with  the  coldest  periods  in  Europe  and with the North Atlantic thermohaline circulation. However, further investigations, such as additional coring and high-resolution coastal imagery, are needed to better constrain the main cause of these multiple events.

L. Dezileau, A. Pérez-Ruzafa, P.  Blanchemanche, J.-P. Degeai, O. Raji, P. Martinez, C. Marcos,  U. von Grafenstein

Clim. Past, 12, 1389–1400.

 

 

 

 

 

 

 

Last update : 03/20 2017 (115)

Retour en haut