The 2012–2013 earthquake swarm in the eastern Guadalquivir basin (South Spain): A case of heterogeneous faulting due to oroclinal bending

Morales, J.; Azañón, José Miguel; Stich, Daniel; Roldán, Francisco Javier; Pérez-Peña, Jose Vicente; Martín, Ricardo Muñoz; Cantavella, Juan Vicente; Martín, J.B.; Mancilla, Flor de Lis; González-Ramón, Antonio

doi:10.1016/j.gr.2014.10.017

Cited by 16 publications

(29 citation statements)

References 34 publications

(44 reference statements)

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“…Seismic swarms have been attributed to the following: (i) Heterogeneities in the source volume and consequently in the stress distribution (Mogi, 1963;Morales et al, 2015), (ii) decrease in fault strength due to fluid flow and pore pressure fluctuations (Kato et al, 2010;Špičák & Horálek, 2001;Wicks et al, 2006), (iii) aseismic slip that generates microseismicity through the loading of neighboring areas of a fault zone (Lohman & McGuire, 2007;Peng & Gomberg, 2010;Takada & Furuya, 2010), and (iv) a combination of the last two (Vidale & Shearer, 2006).…”

Section: Earthquake Clusteringmentioning

confidence: 99%

An Active Seismic Zone in Intraplate West Iberia Inferred From High‐Resolution Geophysical Data

et al. 2018

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Intraplate Iberia is a region of slow lithopsheric deformation (<1 mm/yr) with significant historical earthquake activity. Recent high‐quality instrumental data have shown that small‐magnitude earthquakes collapse along clusters and lineaments, which however do not bear a clear relationship to geologically mapped active structures. In this article, we investigate the controls of these earthquake clusters. In particular, we study two of the identified clusters—the Arraiolos and the Évora seismic zones (ASZ and ESZ), located in the Western Ossa Morena Zone, southwest Iberia. The ASZ marks a sharp boundary between a seismically active region to its south and a more quiet region to its north. We revise historical earthquakes in order to clarify whether earthquake activity in the region is persistent. We use data from a local network to compute accurate epicenters, focal depth, focal mechanisms, and spatiotemporal clustering, thus characterizing ongoing small‐scale fracturing. Finally, we analyze complementary data sets, including tomographic models, Global Navigation Satellite Systems data, magnetic anomalies, and gravity anomalies, in order to discuss the factors that control seismogenesis in the two seismic zones. Consistency between earthquake locations, focal mechanisms and Global Navigation Satellite Systems data suggests that the ASZ is an active right‐lateral shear zone, which divides two blocks within the Western Ossa Morena Zone. The ESZ seems to localize microseismicity due to its granitic lithology. These results suggest that high‐resolution geophysical data have the potential to reveal blocks with different seismogenic and rheological behaviors, which may be used to improve our understanding of fault systems and the assessment of earthquake hazard in slowly deforming regions.

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Section: Earthquake Clusteringmentioning

confidence: 99%

An Active Seismic Zone in Intraplate West Iberia Inferred From High‐Resolution Geophysical Data

et al. 2018

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“…Considering that the area is not volcanic, it is likely that fluid movements or slow earthquakes were responsible for the swarm activity in the years 2012-13 in TorreperogilSabiote area. The potential processes were also suggested based on the analysis of the hypocenter distribution and seismotectonic structures by Morales et al (2015).…”

Section: Discussionmentioning

confidence: 99%

“…The re-localizations of the main sequence reveal some clustering in the main activity period as well Morales et al 2015). In order to perform a statistical analysis of the seismic series, the first step is to select the subseries which are best suited to characterize the evolution of the plenary incident in time.…”

Section: Datamentioning

confidence: 99%

“…The epicentral area was located within the eastern Guadalquivir basin, beneath an elongated ridge known as Loma de Ubeda, between the towns of Torreperogil and Sabiote. A recent study on structural data revealed a previously unknown shear zone including right and left lateral blind faults where their parallel geometry does not promote static triggering (Morales et al 2015). The shallow and dense distribution of epicenters caused that many events were felt, raising a considerable social concern and a debate about the tectonic or hydro-seismic origin; such as human made changes in aquifers and reservoirs (Doblas et al 2014).…”

mentioning

confidence: 99%

“…The shallow and dense distribution of epicenters caused that many events were felt, raising a considerable social concern and a debate about the tectonic or hydro-seismic origin; such as human made changes in aquifers and reservoirs (Doblas et al 2014). Morales et al (2015) discard this idea associate the initiation of this swarm activity with slow strain release in small but highly fragmented region under a bending scheme.…”

mentioning

confidence: 99%

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Statistical analysis of the 2012–2013 Torreperogil–Sabiote seismic series, Spain

2017

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The study of earthquake swarms and their characteristics can improve our understanding of the transient processes that provokes seismic crises. The spatio-temporal process of the energy release often linked with changes of statistical properties and thus seismicity parameters can help to reveal the underlying mechanism in time and space domains. Here we study the Torreperogil-Sabiote 2012-2013 seismic series (Southern Spain), which was relatively long lasting and it was composed by more than 2000 events. The largest event was a magnitude 3.9 event which occurred at 5 th of February 2013. It caused slight damages, but it cannot explain the occurrence of the whole seismic crises which was not a typical mainshockaftershock sequence. To shed some light on this swarm occurrence, we analyze the change of statistical properties during the evolution of the sequence; in particular, related to the magnitude and interevent-time distributions. Furthermore, we fit a modified version of the epidemic type aftershock sequence (ETAS) model in order to investigate changes of the background rates and the trigger potential. Our results indicate that the sequence was driven by an aseismic transient stressing rate and that the system passes after the swarm occurrence to a new forcing regime with more typical tectonic characteristics.

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An evaporite‐bearing accretionary complex in the northern front of the Betic‐Rif orogen

et al. 2017

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The Guadalquivir Accretionary Complex forms a largely oblique prism at the northern edge of the Betic‐Rif orogen, where Miocene sediments plus allochthonous evaporite‐bearing units were accreted during the displacement of the Alborán Domain toward the west. Traditional interpretations end the tectonic structuring of the Betic Cordillera at the present topographic front, beyond which gravitational and/or diapiric processes would predominate. However, this study shows pervasive tectonic deformation in the outer prism with coherent oblique shortening kinematics, which is achieved through an alternation of roughly N‐S arcuate thrust systems connected by E‐W transfer fault zones. These structures accord well with the geophysical models that propose westward rollback subduction. The main stage of tectonic activity occurred in the early‐middle Miocene, but deformation lasted until the Quaternary with the same kinematics. Evaporite rocks played a leading role in the deformation as evidenced by the suite of ductile structures in gypsum distributed throughout the area. S‐ and L‐ gypsum tectonites, scaly clay fabrics, and brittle fabrics coexist and consistently indicate westward motion (top to 290°), with subordinate N‐S contraction almost perpendicular to the transfer zones. This work reveals ductile tectonic fabrics in gypsum as a valuable tool to elucidate the structure and deformational history of complex tectonic mélanges involving evaporites above the décollement level of accretionary wedges.

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The 2012–2013 earthquake swarm in the eastern Guadalquivir basin (South Spain): A case of heterogeneous faulting due to oroclinal bending

Cited by 16 publications

References 34 publications

An Active Seismic Zone in Intraplate West Iberia Inferred From High‐Resolution Geophysical Data

An Active Seismic Zone in Intraplate West Iberia Inferred From High‐Resolution Geophysical Data

Statistical analysis of the 2012–2013 Torreperogil–Sabiote seismic series, Spain

An evaporite‐bearing accretionary complex in the northern front of the Betic‐Rif orogen

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