Extreme sea events during the last millennium in the northeast of Morocco

Raji, Otmane; Dezileau, Laurent; Grafenstein, Ulrich von; Niazi, Saïda; Snoussi, Maria; Martinez, Philippe

doi:10.5194/nhess-15-203-2015

Cited by 39 publications

(29 citation statements)

References 36 publications

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“…In the present study we chose the ratio Si / Al and Zr / Al, which better discriminate between the two source areas: marine vs. drainage basin (Dezileau et al, 2011;Sabatier et al, 2012;Raji et al, 2015). The high Zr / Al ratio value is probably explained by the presence of heavy minerals (like zircon) from marine sand, and the high Si / Al ratio is due to quartz minerals in marine sand.…”

Section: Sediment Sourcementioning

confidence: 99%

Extreme storms during the last 6500 years from lagoonal sedimentary archives in the Mar Menor (SE Spain)

et al. 2016

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Abstract. 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, a region where high-frequency occurrences of these extreme events coincides with some of the most densely populated coastal areas in the world. 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 20th and 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 four 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 evidenced 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.

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Section: Sediment Sourcementioning

confidence: 99%

Extreme storms during the last 6500 years from lagoonal sedimentary archives in the Mar Menor (SE Spain)

et al. 2016

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“…One of the most impressive pieces of evidence of extreme wave impact on the Mediterranean coasts is represented by the occurrence of mega-boulders, sparse or in fields or berms whose accumulations have been attributed both to tsunamis and storm events Sansò, 2000, 2004;Mastronuzzi et al, 2007;Scicchitano et al, 2007Scicchitano et al, , 2012Barbano et al, 2010;Vacchi et al, 2012;Raji et al, 2015). Notwithstanding the impressive growth in the last 50 years of studies aimed to develop an appropriate methodology, which may (in the absence of field witnesses) link these boulder deposits to a well-defined process (Williams and Hall, 2004;Hall et al, 2006;Mastronuzzi et al, 2006;Scheffers and Scheffers, 2006;Pignatelli et al, 2009;Goto et al, 2010), no undisputed consensus has yet been reached on how to differentiate between the boulders accumulated by a sea storm from those deposited by a tsunami.…”

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confidence: 99%

Boulder accumulations related to extreme wave events on the eastern coast of Malta

Biolchi

Furlani

Antonioli

et al. 2016

Nat. Hazards Earth Syst. Sci.

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Abstract. The accumulation of large boulders related to waves generated by either tsunamis or extreme storm events have been observed in different areas of the Mediterranean Sea. Along the eastern low-lying rocky coasts of Malta, five sites with large boulder deposits have been investigated, measured and mapped. These boulders have been detached and moved from the nearshore and the lowest parts of the coast by sea wave action. In the Sicily-Malta channel, heavy storms are common and originate from the NE and NW winds. Conversely, few tsunamis have been recorded in historical documents to have reached the Maltese archipelago.We present a multi-disciplinary study, which aims to define the characteristics of these boulder accumulations, in order to assess the coastal geo-hazard implications triggered by the sheer ability of extreme waves to detach and move large rocky blocks inland.The wave heights required to transport 77 coastal boulders were calculated using various hydrodynamic equations. Particular attention was given to the quantification of the input parameters required in the workings of these equations, such as size, density and distance from the coast. In addition, accelerator mass spectrometry (AMS) 14 C ages were determined from selected samples of marine organisms encrusted on some of the coastal boulders. The combination of the results obtained both by the hydrodynamic equations, which provided values comparable with those observed and measured during the storms, and radiocarbon dating suggests that the majority of the boulders have been detached and moved by intense storm waves. These boulders testify to the existence of a real hazard for the coasts of Malta, i.e. that of very high storm waves, which, during exceptional storms, are able to detach large blocks of volumes exceeding 10 m 3 from the coastal edge and the nearshore bottom, and also to transport them inland. Nevertheless, the occurrence of one or more tsunami events cannot be ruled out, since radiocarbon dating of some marine organisms did reveal ages which may be related to historically known tsunamis in the Mediterranean region, such as the ones in AD 963, 1329, 1693 and 1743.

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“…It entered the environment in response to atmospheric nuclear tests from AD 1954 to 1980 that induced global fallout events (the first year of atmospheric releases was AD 1953, whereas the maximum atmospheric production was reached in AD 1963). 137 Cs depth profiles have been extensively used in various environments to assess sediment accumulation rates (Nittrouer et al, 1984;He and Walling, 1996;Radakovitch et al, 1999;Frignani et al, 2004).…”

Section: Bl12-10 Core Datingmentioning

confidence: 99%

“…These fields of research were successfully applied in the western North Atlantic (Donnelly and Woodruff, 2007), northwestern Florida (Liu and Fearn, 2000;Lane et al, 2011;Das et al, 2013), the northeastern United States (Parris et al, 2010), the central Pacific (Toomey et al, 2013), southern Japan (Woodruff et al, 2009), western Australia (Nott, 2011), northeastern New Zealand (Page et al, 2010), northern Europe (Sorrel et al, 2012), or the western Mediterranean (Dezileau et al, 2011(Dezileau et al, , 2016Sabatier et al, 2012;Raji et al, 2015;Degeai et al, 2015). Such studies are still scarce in southern Tunisia, despite the importance of these topics in Mediterranean coastal areas.…”

Section: The El Bibane Lagoon: a Key Region For Palaeohydrological Rementioning

confidence: 99%

“…Few studies have been undertaken to reconstruct past flood events from lagoon sediments (Raji, 2014). Most of the studies were interested in flooding associated with both hurricanes and tsunamis, where overwash deposits are preserved within back-barrier lagoons and salt ponds can provide a means for documenting previous flooding activity (Liu and Fearn, 1993;Donnelly and Woodruff, 2007;Sabatier et al, 2008;Dezileau et al, 2011Dezileau et al, , 2016Raji et al, 2015;Degeai et al, 2015). Heavy rain flooding events recorded within these Figure 1.…”

Section: Introductionmentioning

confidence: 99%

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Extreme flood event reconstruction spanning the last century in the El Bibane Lagoon (southeastern Tunisia): a multi-proxy approach

Affouri

Dezileau

Kallel³

2017

Clim. Past

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Abstract. Climate models project that rising atmospheric carbon dioxide concentrations will increase the frequency and the severity of some extreme weather events. The flood events represent a major risk for populations and infrastructures settled on coastal lowlands. Recent studies of lagoon sediments have enhanced our knowledge on extreme hydrological events such as palaeo-storms and on their relation with climate change over the last millennium. However, few studies have been undertaken to reconstruct past flood events from lagoon sediments. Here, the past flood activity was investigated using a multi-proxy approach combining sedimentological and geochemical analysis of surfaces sediments from a southeastern Tunisian catchment in order to trace the origin of sediment deposits in the El Bibane Lagoon. Three sediment sources were identified: marine, fluvial and aeolian. When applying this multi-proxy approach on core BL12-10, recovered from the El Bibane Lagoon, we can see that finer material, a high content of the clay and silt, and a high content of the elemental ratios (Fe / Ca and Ti / Ca) characterise the sedimentological signature of the palaeo-flood levels identified in the lagoonal sequence. For the last century, which is the period covered by the BL12-10 short core, three palaeo-flood events were identified. The age of these flood events have been determined by 210 Pb and 137 Cs chronology and give ages of AD 1995 ± 6, 1970 ± 9 and 1945 ± 9. These results show a good temporal correlation with historical flood events recorded in southern Tunisia in the last century (AD 1932(AD , 1969(AD , 1979(AD and 1995. Our finding suggests that reconstruction of the history of the hydrological extreme events during the upper Holocene is possible in this location through the use of the sedimentary archives.

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Extreme sea events during the last millennium in the northeast of Morocco

Cited by 39 publications

References 36 publications

Extreme storms during the last 6500 years from lagoonal sedimentary archives in the Mar Menor (SE Spain)

Extreme storms during the last 6500 years from lagoonal sedimentary archives in the Mar Menor (SE Spain)

Boulder accumulations related to extreme wave events on the eastern coast of Malta

Extreme flood event reconstruction spanning the last century in the El Bibane Lagoon (southeastern Tunisia): a multi-proxy approach

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