scholarly journals The 1856 Djijelli (Algeria) earthquake and tsunami: source parameters and implications for tsunami hazard in the Balearic Islands

2008 ◽  
Vol 8 (4) ◽  
pp. 721-731 ◽  
Author(s):  
J. Roger ◽  
H. Hébert
Keyword(s):  
Mediterranean Sea ◽  
Source Parameters ◽  
Western Mediterranean ◽  
Tsunami Hazard ◽  
Balearic Islands ◽  
Tsunami Source ◽  
Geometrical Parameters ◽  
Macroseismic Data ◽  
Coseismic Slip ◽  
Tsunami Modelling

Abstract. In 1856, one (or two) destructive earthquake(s) occurred off Djijelli (Algeria) and probably triggered a tsunami in the western Mediterranean Sea. Following recently published results of marine campaigns along the North-Algerian margin, a new source hypothesis for the earthquake has been proposed, and is constituted with a set of three "en échelon" fault segments positioned in agreement with previous studies of this earthquake and with macroseismic data available. The geometrical parameters for this source, in agreement with a Mw = 7.2 earthquake, display an average 40° NW dip, a 80° strike and mean dimensions of 80 km (length) × 20 km (width). A coseismic slip of 1.5 m is consistent with an average convergence rate of about 5–6 mm/yr and a recurrence period of 300–400 years. They are then introduced in the tsunami modelling code to study the propagation across the Mediterranean Sea with a special attention towards the Balearic Islands. A focus on the two major towns, Palma (Majorca) and Mahon (Minorca) Harbours shows that these places are not the most exposed (maximum water heights less than 1 m) by tsunami waves coming from this part of the African margin. Specific amplifications revealed by modelling occur off the southern coast of Minorca and the southeastern coast of Majorca, mostly related to submarine bathymetric features, and are able to produce coastal wave heights larger than 1 to 2 m as offshore Alcalfar (Minorca). A deep submarine canyon southward Minorca leads to the amplification of waves up to two times on both sides of the canyon. However these modellings could not be compared to any historical observations, non-existent for these sites. This work is a contribution to the study of tsunami hazard in western Mediterranean based on modelling, and offers a first assessment of the tsunami exposure in the Balearic Islands.

Closing the gap: New data on the last documented Myotragus and the first human evidence on Mallorca (Balearic Islands, Western Mediterranean Sea)

The Holocene ◽  
2016 ◽  
Vol 26 (11) ◽  
pp. 1887-1891 ◽  
Author(s):  
Pere Bover ◽  
Alejandro Valenzuela ◽  
Enric Torres ◽  
Alan Cooper ◽  
Joan Pons ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Western Mediterranean ◽  
Balearic Islands ◽  
Western Mediterranean Sea ◽  
Closing The Gap

scholarly journals Repeated fluid expulsions during events of rapid sea-level rise in the Gulf of Lion, western Mediterranean Sea

2017 ◽  
Vol 188 (4) ◽  
pp. 24 ◽  
Author(s):  
Aurélien Gay ◽  
Thibault Cavailhès ◽  
Dominique Grauls ◽  
Bruno Marsset ◽  
Tania Marsset
Keyword(s):  
Sea Level Rise ◽  
Mediterranean Sea ◽  
Sea Level ◽  
Western Mediterranean ◽  
Unconsolidated Sediments ◽  
Geometrical Parameters ◽  
Near Surface ◽  
Western Mediterranean Sea ◽  
Gulf Of Lion ◽  
Potential Fluid

Based on a High-Resolution 3D seismic block acquired in the Gulf of Lion in 2004–2005 we investigated fluid pipes and pockmarks on the top of the interfluve between the Hérault canyon and the Bourcart canyon both created by turbidity currents and gravity flows from the shelf to the deep basin in the north-western Mediterranean Sea. Combining the geometry of the potential fluid pipes with the induced deformation of surrounding sediments leads then to the ability to differentiate between potential fluid sources (root vs source) and to better estimate the triggering mechanisms (allochtonous vs. autochtonous cause). We linked together a set of derived attributes, such as Chaos and RMS amplitude, to a 3D description of pipes along which fluids may migrate. As previously shown in other basins, the induced deformation, creating cone in cone or V-shaped structures, may develop in response to the fluid pipe propagation in unconsolidated sediments in the near surface. The level at the top of a cone structure is diachronous. It means that stratigraphic levels over this surface are deformed at the end of the migration. They collapse forming a depression called a pockmark. These pipes are the result of repeated cycles of fluid expulsion that might be correlated with rapid sea-level rise instead of sediment loading. The most recent event (MIS 2.2 stage) has led to the formation of a pockmark on the modern seafloor. It has been used as a reference for calculating the effect of a rapid sea-level rise on fluid expulsion. As all physical and geometrical parameters are constrained, we were able to define that a + 34 m of sea level rise may account for triggering fluid expulsion from a very shallow silty-sandy layer at 9 m below seafloor since the last glacial stage. This value is consistent with a sea level rise of about 102 m during this period. This study shows that the episodic nature of fluid release resulted from hydromechanical processes during sea-level rise due to the interactivity between high pressure regimes and principal in situ stresses.

scholarly journals First record of the genus Paranebalia Claus, 1880 (Crustacea: Leptostraca) from the Mediterranean Sea

2017 ◽  
Vol 18 (2) ◽  
pp. 332
Author(s):  
J. MOREIRA ◽  
J. JUNOY
Keyword(s):  
New Species ◽  
Mediterranean Sea ◽  
Type Species ◽  
Taxonomic Status ◽  
First Record ◽  
Western Mediterranean ◽  
Balearic Islands ◽  
The Third ◽  
The Mediterranean ◽  
A New Species

Benthic monitoring of the marine shallow bottoms off Menorca (Balearic Islands, western Mediterranean) has yielded several specimens of the leptostracan genus Paranebalia Claus, 1880. This finding constitutes the first report of the genus from European latitudes and the Mediterranean Sea and therefore the third leptostracan genus known from the Mediterranean. Specimens are described, illustrated and compared to other known species; they might represent a new species but their state of maturity and the lack of an appropriate diagnosis for the type species of the genus, Paranebalia longipes (Willemöes-Suhm, 1875), did not allow to confirm its taxonomic status.

scholarly journals Sponges of Western Mediterranean seamounts: new genera, new species and new records

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11879
Author(s):  
Julio A. Díaz ◽  
Sergio Ramírez-Amaro ◽  
Francesc Ordines
Keyword(s):  
Mediterranean Sea ◽  
First Record ◽  
Western Mediterranean ◽  
Balearic Islands ◽  
Sampling Device ◽  
Great Opportunity ◽  
The North ◽  
Western Mediterranean Sea ◽  
The Mediterranean ◽  
First Time

Background The seamounts Ses Olives (SO), Ausias March (AM) and Emile Baudot (EB) at the Mallorca Channel (Balearic Islands, western Mediterranean), are poorly explored areas containing rich and singular sponge communities. Previous works have shown a large heterogeneity of habitats, including rhodolith beds, rocky, gravel and sandy bottoms and steeped slopes. This diversity of habitats provides a great opportunity for improving the knowledge of the sponges from Mediterranean seamounts. Methods Sponges were collected during several surveys carried out by the Balearic Center of the Spanish Institute of Oceanography at the Mallorca Channel seamounts. Samples were obtained using a beam-trawl, rock dredge and remote operated vehicle. Additional samples were obtained from fishing grounds of the Balearic Islands continental shelf, using the sampling device GOC-73. Sponges were identified through the analysis of morphological and molecular characters. Results A total of 60 specimens were analyzed, from which we identified a total of 19 species. Three species and one genus are new to science: Foraminospongia balearica gen. nov. sp. nov., Foraminospongia minuta gen. nov. sp. nov. and Paratimea massutii sp. nov. Heteroxya cf. beauforti represents the first record of the genus Heteroxya in the Mediterranean Sea. Additionally, this is the second report of Axinella spatula and Haliclona (Soestella) fimbriata since their description. Moreover, the species Petrosia (Petrosia) raphida, Calyx cf. tufa and Lanuginella pupa are reported for the first time in the Mediterranean Sea. Petrosia (Strongylophora) vansoesti is reported here for the first time in the western Mediterranean Sea. Haliclona (S.) fimbriata is reported here for the first time in the north-western Mediterranean Sea. Hemiasterella elongata is reported here for the second time in the Mediterranean Sea. The species Melonanchora emphysema, Rhabdobaris implicata, Polymastia polytylota, Dragmatella aberrans, Phakellia ventilabrum and Pseudotrachya hystrix are reported for first time off Balearic Islands. Following the Sponge Barcoding project goals, we have sequenced the Cytochrome Oxidase subunit I (COI) and the 28S ribosomal fragment (C1–D2 domains) for Foraminospongia balearica sp. nov., Foraminospongia minuta sp. nov., H. cf. beauforti and C. cf. tufa, and the COI for Paratimea massuti sp. nov. We also provide a phylogenetic analysis to discern the systematic location of Foraminospongia gen. nov., which, in accordance to skeletal complement, is placed in the Hymerhabdiidae family. A brief biogeographical discussion is provided for all these species, with emphasis on the sponge singularity of SO, AM and the EB seamounts and the implications for their future protection.

Characterizing an anticyclone in Western Mediterranean Sea using altimetric data and an eddy tracker

2021 ◽  
Author(s):  
Cécile Pujol ◽  
Aida Alvera-Azcárate ◽  
Charles Troupin ◽  
Alexander Barth ◽  
Hugo Romanelli
Keyword(s):  
High Resolution ◽  
Mediterranean Sea ◽  
Western Mediterranean ◽  
Anticyclonic Eddy ◽  
Balearic Islands ◽  
Sea Level Anomaly ◽  
Entire Life ◽  
Satellite Sst ◽  
Western Mediterranean Sea ◽  
Altimetric Data

<p>In April 2019, a large anticyclonic Eddy has formed in Western Mediterranean Sea between Sardinia and Balearic Islands. This anticyclone was observable with Sentinel-3 SST satellite data for 7 months and its diameter was estimated to 150 km. Although mesoscale anticyclones are quite common in this part of the Mediterranean Sea, such large and long-live eddies remain exceptional and repercussions for ocean-atmospheric exchanges and for biodiversity might be consequent. However, due to the increase of temperatures during summer, the satellite SST track of the eddy has been lost during a few weeks in August and September. Indeed, the SST signature of the eddy was not distinguishable from surrounding waters anymore. In order to track the eddy during its entire life and have a better understanding of its characteristics, sea level anomaly derived from altimetric data will be analysed in this study with the Py Eddy Tracker toolbox to investigate the variation of its position, its altimetry and its size. The distribution of other remarkable eddies in this zone and period will also be considered. Moreover, a high-resolution SST field will be reconstructed with DINEOF method so the comparison between eddy’s SST and altimetric characteristics will be assured.</p>

A new approach using biomarkers to elucidate the regression state of the invasive alga Caulerpa taxifolia in waters around the Balearic Islands (Western Mediterranean Sea)

2013 ◽  
Vol 64 (10) ◽  
pp. 986 ◽  
Author(s):  
Silvia Tejada ◽  
Antoni Sureda
Keyword(s):  
Lipid Peroxidation ◽  
Mediterranean Sea ◽  
Native Species ◽  
Western Mediterranean ◽  
Balearic Islands ◽  
Antioxidant Enzyme Activities ◽  
Caulerpa Taxifolia ◽  
Western Mediterranean Sea ◽  
And Function ◽  
Invasive Alga

Invasive algae alter the structure and function of ecosystems. The green alga Caulerpa taxifolia is an invasive alga introduced in the Mediterranean Sea, whereas Caulerpa prolifera is a native species in Mediterranean waters. The aim of the current work was to determine the oxidative status of both Caulerpa species by means of biomarker measures as a possible indicator of the regression state of C. taxifolia in waters around the Balearic Islands (western Mediterranean Sea). The levels of markers of lipid peroxidation, glutathione concentration, activities of antioxidant enzymes and caulerpenyne production were measured in C. prolifera and C. taxifolia fronds. The concentration of the end product of lipid peroxidation, malondialdehyde, was significantly higher in C. taxifolia than in C. prolifera samples. Antioxidant enzyme activities, namely superoxide dismutase glutathione peroxidase and glutathione reductase, as well as the reduced glutathione : glutathione disulfide ratio were lower in C. taxifolia than in C. prolifera, although the concentrations of malondialdehyde were higher in the alien species. No differences were found in catalase activity or in the concentration of caulerpenyne. In conclusion, the invasive alga C. taxifolia presented a more oxidised status, which could be related to its regression in Mallorcan coastal waters.

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