Geotechnical characteristics of the soils of Huelva town: index properties and consolidation test

This paper shows the preliminary results of a laboratory geotechnical test for the identification and determination of consolidation properties of the soils of Huelva. The fine-grained soils (Arcillas de Gibraleón, Arenas de Huelva and Arenas de Bonares units) have a high consistency. These are over-consolidated soils which have few compressibilities. The Arcillas de Gibraleón Unit presents expansive clay mineral

Seismotectonics related to the Azores – Gibraltar Fracture Zone: Analysis of the February 12th 2007 earthquake, SW Gorringe Bank

This work deals with the analysis of the seismicity and tectonic evolution of the eastern end of the Azores – Gibraltar Fracture Zone. The location of the main seismogenetic areas in this region is related to the complex geometry of the boundary between the Iberian and African lithospheric plates. To the west of the San Vicente Cape the seismicity can be related to a local compression at the Gorringe Bank. A detailed seismotectonic analysis allows the geological interpretation of the position of the hypocenter for the 12th February 2007 earthquake. It had Mw 6.0 and was placed on a fault having a NNE-SSW strike and a high dip to NW. The fault shows an oblique displacement (sinistral) and locates in the margin of the Horseshoe abyssal basin. Displacement along this fault is here tentatively related to complex deformation in the outer swell of an incipient downgoing plate. This can be the first indication of the beginning of subduction of the northern part of the African plate under the continental margin of Iberia. On the other hand, an analysis of the location of earthquakes having Mw >6.0 generated to the SW of the San Vicente Cape and the estimated isoseismal map has been made. It can be noted the importance of the uppermost crustal materials on the seismic intensity measurement. Sea waves resulting from these earthquakes and measured in the littoral of the Huelva province have an average velocity of propagation of approximately 600 km/

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Seismicity in the boundary of plates between Eurasia and Africa on SW Iberian, from 1984 to 1994

Spatial distribution of earthquakes in the SW iberian margin has been studied for the period 1984-1994. in the basement of the continental margin of iberia active fault zones occur, showing different trends: NW-SE, NE-SW and E-W. Seismicity is focused in a major limit between two continental blocks. It is concluded that this limit is an active fracture zone, extending from the Huelva meridian at least to the San Vicente cape. Crust in the SW Iberian margin is estimated to be about 30-35 km thick, whereas a thickness of 60 km is suggested for the whole lithospher

Progressive deformation in the South Portuguese Zone: Folding and shearing of multilayers

Folds, reverse faults and thrusts in the South Portuguese Zone (SW Iberia) have been classically related with the progressive deformation of the Variscan thrust -fold belt. All structures verge toward South and Southwest. The style of folds in multilayers is analysed in this work. Ductile, brittle-ductile and brittle shear zones cut across the tight folds wisch exibit a WNW-ESE trend. The dip of axial surfaces varies from moderately inclined to upright. Detailed research in the Valverde del Camino anticlinal has revealed the existence of dome-basin patterns of folds related with the thrusts. The regional structures such as the Puebla de Guzmán and Valverde del Camino anticlinorium are associated with the geometry of thrust

A seismotectonic proposal for the eastern end of the Azores-Gibraltar Fracture Zone in the area comprised between the Gorringe and the Guadalquivir Banks

Este trabajo describe la terminación oriental de la Zona de Fractura Azores- Gibraltar y se propone, basándonos de datos sísmicos, la existencia de una zona de “restraining bend” formada por fallas inversas de dirección NESO y fallas E-O de desplazamiento en dirección. A partir de una revisión de datos geológicos y geofísicos, incluyendo perfiles sísmicos de reflexión y el registro instrumental de la sismicidad para el periodo 2004-2010, hemos podido definir el citado “restraining bend” como una importante zona transpresiva dextrorsa, con una forma romboidal -en planta-, ligada al límite actual entre las placas Africana y Euroasiática, y comprendida entre la Falla Gloria y el Arco de Gibraltar. La cinemática de las placas en dicho límite es congruente con la orientación del patrón estimado para las trayectorias de SH: NNO-SSEThis work describes the eastern part of the Azores-Gibraltar Fracture Zone and it proposes, mainly based on seismic data, the activity of a restraining bend consisting of NE-SW reverse faults and E-W-oriented strikeslip faults. A review of geological and geophysical data, including seismic reflection profiles and the use of catalogs of instrumental seismicity for the period 2004-2010, allow to define this restraining bend as a huge dextral transpression zone, with a rhomboidal shape in plan view, outlining the present- day boundary between the African and Eurasian plates at the segment comprised between the Gloria Fault and the Gibraltar Arc. The plate kinematics at this boundary is consistent with the estimated pattern of NNW-SSEtrending SH trajectorie

β-stress method to correct the orientation of the main axis of effort based on the population analysis of incomplete systems of faults with orthorhombic symmetry

En fallas que siguen el modelo de deslizamiento, la utilización de las técnicas de análisis de poblaciones de fallas para obtener la orientación y magnitud de los ejes principales del esfuerzo a partir de sistemas incompletos (menos de cuatro familias), suele proporcionar orientaciones inclinadas para dichos ejes. Se puede demostrar que, en sistemas completos (es decir, con cuatro familias de fallas), las variaciones en el buzamiento de las familias de fallas y en el cabeceo de las estrías no modifican la dirección ni la inmersión del aquí llamado eje invariante del esfuerzo (σ1 para fallas inversas y σ3 para fallas normales). Esta observación ha permitido desarrollar un método empírico para corregir la orientación de los ejes invariantes del esfuerzo en sistemas incompletos de fallas, al que se ha denominado método β-stress, asumiéndose que uno de los ejes principales del esfuerzo es vertical. La técnica consiste en la determinación de la desviación en el ángulo medido en la horizontal (ángulo β) entre la dirección de inmersión del eje invariante inclinado calculado a partir del sistema incompleto, y la posición no desviada del eje que teóricamente debe haber afectado al sistema de fallas, y que habríamos medido en caso de haber dispuesto de las cuatro familias del sistema. El método se ha aplicado con éxito para la corrección de los ejes del esfuerzo obtenidos tras el análisis de fallas de edades miocenas y plioceno-cuaternarias localizadas en el área emergida del Golfo de Cádiz.The techniques of fault-slip stress inversion can be used on faults that follow the slip model (with four fault sets arranged in a system with orthorhombic symmetry) to determine the position and magnitude of the principal stress axes. In incomplete fault systems (less than four sets) the calculated stress axes are commonly inclined. It is shown here that, in complete fault systems, variations in fault dip and striae pitch do not modify the trend or the plunge of the here-called invariant stress axis (σ1 for reverse faults and σ3 for normal faults). This feature allowed us to propose a new empirical technique, the β-stress method, to correct the position of the invariant stress axes in incomplete fault systems. One of the assumptions of the method is that one of the principal stress axis is vertical. The β-stress method yields the horizontal deviation angle, β, between the trend of an inclined invariant axis determined from an incomplete fault system, and the theoretical, correct attitude of this axis, which would have been measured if the four sets of the complete system were available at the studied outcrop. The method has been successfully applied to correct the orientation of the principal stress axes obtained after stress inversion of Miocene and Pliocene-Quaternary faults located in the Gulf of Cádiz

The geological map: 2-D and 3-D paper models. A proposal for learning to “think in 3-D”

En este trabajo se presentan algunas ideas que pueden aplicarse en clase para que los estudiantes aprendan las técnicas y principios del mapa geológico. Los estudiantes tendrán la oportunidad de conocer el arte de hacer un mapa geológico. Cualquier profesor puede seguir las explicaciones detalladas del texto y con ello hacer pensar a los estudiantes sobre: i) las curvas de nivel en los mapas topográficos, ii) patrones de afloramiento de los contactos geológicos y las reglas de la “V”, iii) espesor real y aparente de los niveles geológicos (estratos / unidades). Las láminas que hemos elaborado, a modo de modelos geológicos 2-D y 3-D dibujados en papel, ayudan a entender mejor el concepto mismo del mapa geológico. Este trabajo presenta un caso práctico que analiza la elaboración del mapa geológico de la ciudad de Huelva y un modelo geológico tridimensional donde se observan estratos subhorizontales.This paper presents a series of techniques that teachers can use in the classroom to familiarise their students with the fundamentals of geological mapping. By following the detailed practical explanations provided in this text, teachers can guide students to think about: i) topographical contour maps, ii) geological outcrop patterns and the V-rule, iii) true and apparent thickness of layers (strata/units). The sheets (2-D and 3-D geological paper models) provided herein offer a better understanding of the concept of geological maps. A practical case study is described that analyses the geological mapping of the city of Huelva, also presenting a 3-D geological model with sub-horizontal strata