Improving the location of induced earthquakes associated with an underground gas storage in the Gulf of Valencia (Spain)

On September 2013, increased seismic activity was recorded near the CASTOR offshore underground gas storage (UGS), in the Gulf of Valencia (Spain). According to the reports by the Spanish Instituto Geográfico Nacional (IGN), more than 550 events occurred during two months, the strongest having a magnitude of Mw = 4.2 which took place two weeks after the gas injection stopped. The low magnitude of the events (with only 17 earthquakes having mbLg greater than 3), the lack of nearby stations, and the inhomogeneous station distribution made the location problem a great challenge. Here we present improved locations for a subset of 161 well recorded events from the earthquake sequence using a probabilistic nonlinear earthquake location method. A new 3-D shear-wave velocity model is also estimated in this work from surface-wave ambient noise tomography. To further improve the locations, waveform cross-correlations are computed at each station for every event pair and new locations are obtained from an inverted set of adjusted travel time picks. The resulting hypocentral solutions show a tighter clustering with respect to the initial locations and they are distributed in a NW-SE direction. Most of the earthquakes are located near the injection well at depths of about 6 km. Our results indicate that the observed seismicity is closely associated with the injection activities at the CASTOR underground gas storage and may have resulted from the reactivation of pre-existing unmapped faults, located a few kilometers below the reservoir. © 2016 Elsevier B.V.This research was partially funded by project MISTERIOS (CGL2013-48601-C2-1-R).Peer reviewe

Ebre Observatory Contribution to the IAGA International Service of Rapid Magnetic Variations

[EN] The rapid magnetic variations constitute a preferential research field inside the terrestrial magnetism of external origin. The origin of these variations has to be placed in the solar activity and its fluctuations. The Ebre Observatory, following its foundational research line, has been participating very actively in the development of the knowledge of the rapid magnetic variations in both theoretical and practical works, from its foundation. It has been also strongly involved in the organizing activity by taking part in committees and international organizations created to foster its knowledge, which culminated with the acceptance of assuming the International Service of Rapid Magnetic Variations. In this paper we make a historical survey of these actions in the framework of the international movements that drove its development.[ES] Las variaciones magnéticas rápidas presentan un campo de investigación preferente dentro del magnetismo terrestre de origen externo. El origen de estas variaciones hay que buscarlo en la actividad solar y sus fluctuaciones. El Observatorio del Ebro, fiel a su línea de investigación fundacional, ha participado activamente desde su creación en el desarrollo del conocimiento de las variaciones rápidas tanto en trabajos teóricos como prácticos. También se ha realizado un gran esfuerzo en la vertiente organizativa estando presente en aquellos comités y organizaciones internacionales que se hayan creado para el fomento de su conocimiento culminando con el hecho de asumir el Servicio Internacional de Variaciones Magnéticas Rápidas. En este artículo se hace un repaso histórico de todas estas actuaciones encuadrándolas en los movimientos internacionales que en cada momento impulsaron su desarrollo.Peer reviewe

Seismicity at the Castor gas reservoir driven by pore pressure diffusion and asperities loading

We are thankful to Dr. J. V. Cantavella and IGN for providing waveform data and metadata of the network ES. S.C. and P.N. received funding by the European Union RFCS project PostMinQuake grant 899192. J.A.L.-C. was financed by the European Union's Horizon 2020 research and innovation program under the Marie Skodowska-Curie grant agreement 754446 and UGR Research and Knowledge Transfer Found-Athenea3i and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - Projektnummer (407141557). D.S. received funding by the Spanish National FEDER/MINECO Project PID2019-109608GB-I00/AEI/10.13039/501100011033, FEDER/Junta de Andalucia project A-RNM-421-UGR18 and Research group RNM104 of the Junta de Andalucia. F.G. was financed by the European Union's Horizon 2020 Framework Programme under the Marie Skodowska Curie Grant agreement (790900).The 2013 seismic sequence at the Castor injection platform offshore Spain, including three earthquakes of magnitude 4.1, occurred during the initial filling of a planned Underground Gas Storage facility. The Castor sequence is one of the most important cases of induced seismicity in Europe and a rare example of seismicity induced by gas injection into a depleted oil field. Here we use advanced seismological techniques applied to an enhanced waveform dataset, to resolve the geometry of the faults, develop a greatly enlarged seismicity catalog and record details of the rupture kinematics. The sequence occurred by progressive fault failure and unlocking, with seismicity initially migrating away from the injection points, triggered by pore pressure diffusion, and then back again, breaking larger asperities loaded to higher stress and producing the largest earthquakes. Seismicity occurred almost exclusively on a secondary fault, located below the reservoir, dipping opposite from the reservoir bounding fault.European Union RFCS project PostMinQuake grant 899192European Union's Horizon 2020 research and innovation program under the Marie Skodowska-Curie grant 754446UGR Research and Knowledge Transfer Found-Athenea3iGerman Research Foundation (DFG) 407141557Spanish National FEDER/MINECO Project PID2019-109608GB-I00/AEI/10.13039/501100011033FEDER/Junta de Andalucia project A-RNM-421-UGR18Junta de Andalucia RNM104European Union's Horizon 2020 Framework Programme under the Marie Skodowska Curie Grant 79090

Geomagnetism at Ebro: Presents and Futures

Póster presentado en el International Workshop "Challenges for Geomagnetism Aeronomy and Seismology in the XXI Century: on the occasion of the Centennial Of Ebro Observatory", celebrado en Roquetes, Tarragona, España, 29 septiembre - 10 octubre 2004.Nowadays many research activities and services are performed at the magnetic section of Ebro Observatory. This work displays some of them: Studies of Sq assymetry, Detection of rapid magnetic variations, Automatic detection of SSC, Modelling solar flare and eclipse effects, Reference model for Antarctica, Characterisation of magnetic variations in Antarctica. Most of these scientific projects are related to Solar-Terrestrial Physics. Latest projects are focused on the Antarctic Continent.Peer reviewe

Multi-Station Observations of the 2014 Ursid Meteor Outburst

International audienceWe set up a co-joint campaign (SPMN-FRIPON) to observe the expected Ursid meteor shower outburst of 2014. We have accurately derived the orbits of four meteors

Multi-Station Observations of the 2014 Ursid Meteor Outburst

International audienceWe set up a co-joint campaign (SPMN-FRIPON) to observe the expected Ursid meteor shower outburst of 2014. We have accurately derived the orbits of four meteors

2019 Taurid Bolides Imaged in the Framework of the Spanish Fireball Network

Talk delivered in 51st Lunar and Planetary Science Conference in Texas, USA, 16-20 March 2020.In the continuous monitoring of the night sky over the Iberian Peninsula that is performing from 1999 [1] the Spanish Meteor Network (SPMN) operates about 200 cameras in 30 stations distributed around Spain. Three of the main goals of the SPMN network are obtaining scientific data, providing a rational explanation to bright fireball events, and recover new meteorites. We have a special program dealing with the impact hazard associated with large meteoroids, so gaining insight about the Taurid complex associated with comet 2P/Encke is particularly relevant [1, 2]. Current evidence supports that evolved comets can produce meter-sized meteoroids that are potential meteorite droppers with significant danger by shock waves like e.g. the Chelyabinsk event [3]. We should not forget that the Tunguska event could have been produced by a fragment of comet 2P/Encke [4].Study supported by the Spanish grants PGC2018-097374-B-I00. EB and DA supported by the URL projects 2016-URL-Trac-001 supported by “Obra Social la Caixa” and 2016-URLIR-001 supported by “Generalitat de Catalunya”

Multi-Station Observations of the 2014 Ursid Meteor Outburst

International audienceWe set up a co-joint campaign (SPMN-FRIPON) to observe the expected Ursid meteor shower outburst of 2014. We have accurately derived the orbits of four meteors

The mediterranean diet pattern and its main components are associated with lower plasma concentrations of tumor necrosis factor receptor 60 in patients at high risk for cardiovascular disease

Adherence to aMediterranean diet (MD) is associated with a reduced risk of coronary heart disease. However, themolecular mechanisms involved are not fully understood. The aim of this studywas to compare the effects of 2MD with those of a lowfat- diet (LFD) on circulating inflammatory biomarkers related to atherogenesis. A total of 516 participants included in the PreventionwithMediterraneanDiet Studywere randomized into 3 intervention groups [MD supplementedwith virgin olive oil (MD-VOO); MD supplemented with mixed nuts (MD-Nuts); and LFD]. At baseline and after 1 y, participants completed FFQ and adherence to MD questionnaires, and plasma concentrations of inflammatory markers including intercellular adhesion molecule-1(ICAM-1), IL-6, and 2 TNF receptors (TNFR60 and TNFR80) were measured by ELISA. At 1 y, the MD groups had lower plasma concentrations of IL-6, TNFR60, and TNFR80 (P , 0.05), whereas ICAM-1, TNFR60, and TNFR80 concentrations increased in the LFD group (P , 0.002). Due to between-group differences, participants in the 2 MD groups had lower plasma concentrations of ICAM-1, IL-6, TNFR60, and TNFR80 compared to those in the LFD group (P # 0.028). When participants were categorized in tertiles of 1-y changes in the consumption of selected foods, those in the highest tertile of virgin olive oil (VOO) and vegetable consumption had a lower plasma TNFR60 concentration compared with those in tertile 1 (P,0.02).Moreover, the only changes in consumption thatwere associated with 1-y changes in the geometricmean TNFR60 concentrations were those of VOO and vegetables (P = 0.01). This study suggests that a MD reduces TNFR concentrations in patients at high cardiovascular risk