P‐wave tomographic images in the Central Betics‐Alborán Sea (South Spain) using local earthquakes: Contribution for a continental collision

Serrano, Inmaculada; Morales, J.; Zhao, Dapeng; Torcal, Federico; Vidal, F.

doi:10.1029/1998gl900021

Cited by 33 publications

(18 citation statements)

References 23 publications

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“…However, its offshore continuation is supported by previous tomographic studies (e.g. Serrano et al 1998;Palomeras et al 2014), and the occurrence of the intermediate-depth seismicity (Buforn et al 1995;Morales et al 1997).…”

Section: Active Underthrusting In the Western Betics With The Observasupporting

confidence: 58%

“…The occurrence of intermediate depth seismicity suggests that there are deep heterogeneities in the upper mantle as confirmed by tomographic studies (e.g. Serrano et al 1998;Bijwaard & Spakman 2000;Bezada 2013). A big part of the shallow seismicity is located in southeastern Iberia and northeastern Morocco and it is related with the Trans-Alboran shear zone (Fig.…”

Section: Geological Setting and Previous Analysismentioning

confidence: 67%

“…This underthrusted crust develops into a slab-like structure near the coast, and was previously imaged as a low-velocity anomaly by local (e.g. Serrano et al 1998) and by Rayleigh wave tomography , and coincides with the location of the intermediate-depth seismicity (e.g. Morales et al 1997).…”

Section: Active Underthrusting In the Western Betics With The Observamentioning

confidence: 99%

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Crustal thickness and images of the lithospheric discontinuities in the Gibraltar arc and surrounding areas

Mancilla

Stich

Morales

et al. 2015

Geophysical Journal International

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S U M M A R YThe Gibraltar arc and surrounding areas are a complex tectonic region and its tectonic evolution since Miocene is still under debate. Knowledge of its lithospheric structure will help to understand the mechanisms that produced extension and westward motion of the Alboran domain, simultaneously with NW-SE compression driven by Africa-Europe plates convergence. We perform a P-wave receiver function analysis in which we analyse new data recorded at 83 permanent and temporary seismic broad-band stations located in the South of the Iberian peninsula. These data are stacked and combined with data from a previous study in northern Morocco to build maps of thickness and average v P /v S ratio for the crust, and cross-sections to image the lithospheric discontinuities beneath the Gibraltar arc, the Betic and Rif Ranges and their Iberian and Moroccan forelands. Crustal thickness values show strong lateral variations in the southern Iberia peninsula, ranging from ∼19 to ∼46 km. The Variscan foreland is characterized by a relatively flat Moho at ∼31 km depth, and an average v P /v S ratio of ∼1.72, similar to other Variscan terranes, which may indicate that part of the lower crustal orogenic root was lost. The thickest crust is found at the contact between the Alboran domain and the External Zones of the Betic Range, while crustal thinning is observed southeastern Iberia (down to 19 km) and in the Guadalquivir basin where the thinning at the Iberian paleomargin could be still preserved. In the cross-sections, we see a strong change between the eastern Betics, where the Iberian crust underthrusts and couples to the Alboran crust, and the western Betics, where the underthrusting Iberian crust becomes partially delaminated and enters into the mantle. The structures largely mirror those on the Moroccan side where a similar detachment was observed in northern Morocco. We attribute a relatively shallow strong negativepolarity discontinuity to the lithosphere-asthenosphere boundary. This means relatively thin lithosphere ranging from ∼50 km thickness in southeastern Iberia and northeastern Morocco to ∼90-100 km beneath the western Betics and the Rif, with abrupt changes of ∼30 km under the central Betics and northern Morocco. Our observations support a geodynamic scenario where in western Betics oceanic subduction has developed into ongoing continental subduction/delamination while in eastern Betics this process is inactive.

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Section: Active Underthrusting In the Western Betics With The Observasupporting

confidence: 58%

Section: Geological Setting and Previous Analysismentioning

confidence: 67%

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Crustal thickness and images of the lithospheric discontinuities in the Gibraltar arc and surrounding areas

Mancilla

Stich

Morales

et al. 2015

Geophysical Journal International

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“…Different studies of P-and S-wave seismic tomography reveal that this intermediatedepth seismicity is located in an area of low seismic velocity, which has been interpreted as indicating active subduction of continental crust below the Betic Chain and Alboran Sea (SERRANO et al, 1998;MORALES et al, 1999). At greater depths (between 200 and 700 km), a number of tomographic studies (e.g., BLANCO and SPAKMAN, 1993;CALVERT et al, 2000;SPAKMAN and WORTEL, 2004) have shown a high seismic velocity anomaly below the Betic Chain and Alboran Sea, oriented approximately SW-NE and dipping towards the SE.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Delamination and Convective Removal Numerical Modeling: Comparison with Evolutionary Models for the Alboran Sea Region

Valera

Negredo

Villaseñor

2008

Pure appl. geophys.

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Convective removal and mantle delamination are geodynamical mechanisms proposed to explain the presence of extension in the Alboran Sea within a regional context of compression. Using a new thermomechanical algorithm, we present here a quantitative evaluation and comparison of conceptual models based on these geodynamical mechanisms. In contrast to the in situ convective removal process, the laterally propagating delamination mechanism is shown here to be consistent with first-order features of the Alboran Sea such as the thinning/thickening distribution, intermediate-depth seismicity and upper mantle structure imaged by seismic tomography. The lower crust is predicted to reach depths of 100-150 km in some areas, due to mechanicallydriven viscous drag of the downwelling mantle.

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“…On the other hand, historical earthquakes with maximum intensity of IX or X occurred W of San Vicente Cape (Lisbon earthquake in 1755), southern Iberia (1829 and 1884) and in northern Morocco (1909). At least, seismic activity with magnitude range from 3.5 to 5 at intermediate depth (40< h < 150 km) is further present in this region, as extensively described in literature, Munuera (1963), Hatzfeld (1978), Grimison and Cheng (1986), Buforn et al (1988bBuforn et al ( , 1991aBuforn et al ( , 1991bBuforn et al ( , 1997Buforn et al ( , 2004, Seber et al (1996), Serrano et al (1998), Bezzeghoud et al ( , 2010 gion is dominated by the incidence of moderate magnitude earthquakes, the majority with shallow depth focus in the range 0 < h < 40 km. Nevertheless, significant seismicity at intermediate depths, 40< h < 150 km, with an EW trend and concentrated in Gulf of Cádiz is also present.…”

Section: The Ibero-maghrebian Regionmentioning

confidence: 56%

Seismo-electromagnetic phenomena in the western part of the Eurasia-Nubia plate boundary

Silva

Bezzeghoud

Rocha

et al. 2011

Nat. Hazards Earth Syst. Sci.

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Abstract. This paper presents a work that aims to monitor seismo-electromagnetic phenomena in the Western Part of the Eurasia-Nubia Plate Boundary. This region has a significant tectonic activity combined with relatively low electromagnetic noise levels, rendering high quality seismoelectromagnetic measurements possible. An overview of the seismicity of this region is presented and the research plan is discussed accordingly.

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P‐wave tomographic images in the Central Betics‐Alborán Sea (South Spain) using local earthquakes: Contribution for a continental collision

Cited by 33 publications

References 23 publications

Crustal thickness and images of the lithospheric discontinuities in the Gibraltar arc and surrounding areas

Crustal thickness and images of the lithospheric discontinuities in the Gibraltar arc and surrounding areas

Asymmetric Delamination and Convective Removal Numerical Modeling: Comparison with Evolutionary Models for the Alboran Sea Region

Seismo-electromagnetic phenomena in the western part of the Eurasia-Nubia plate boundary

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