Stable oxygen isotopes of calcite veins in ODP Site 146-892

In situ secondary ionization mass spectrometry (SIMS) analyses of oxygen isotopes in authigenic calcite veins were obtained from an active thrust fault system drilled at Ocean Drilling Program (ODP) Site 892 (44°40.4'N, 125°07.1'W) along the Cascadia subduction margin. The average d18OPDB value of all samples is -9.9 per mil and the values are the lowest of any measured in active accretionary prisms. Ranges in individual veins can be as much as 19.6 per mil. There is an isotopic stratigraphy related to the structural stratigraphy. Mean isotope values in the hanging wall, thrust, and footwall are -14.4 per mil, -9.5 per mil, and -5.2 per mil, respectively. Several veins and crosscutting vein sequences show a general trend from lower to higher d18O values over time. Isotopic and textural data indicate several veins formed by a crack-seal mechanism and growth into open fractures. The best explanation for the strong 18O depletions is periodic rapid flow from 2-3 km deeper in the prism. Relatively narrow isotopic ranges for most veins suggest that fluids were derived from a similar source depth for each episode of fluid pulse and calcite crystallization. Structural and mass balance considerations are consistent with a record preserved in the veins of ten to hundreds of thousands of years. The fluid pulses may relate to periodic large earthquake events such as those recognized in the paleoseismicity records from the Cascadia margin.

Composition of Messinian sediments from the Tyrrhenian Sea

The data base for this study is represented by essentially nonevaporitic Messinian sediments recovered at ODP Sites 654, 653, 652, and 656 along the eastern Sardinian margin, and of the overlying early Pliocene oozes. Grain-size distribution, carbonate content, and microscopic observation of the sand size fractions were investigated. Messinian paleoenvironments, documented in the western Tyrrhenian Sea (ODP Sites 654 and 653), provide additional evidence supporting the deep basin desiccation model. A sharp lithologic contrast between early Pliocene pelagic oozes and latest Messinian conformable gypsiferous silts supports this model. The "lago-mare" biofacies was only occasionally observed in the shallowest site and is limited to the topmost part of the Messinian. Sites 652 and 656, lying in the deeper part of the Tyrrhenian and located on the downthrown side of an important eastward dipping fault system known as "Faglia centrale" are characterized by terrigenous sedimentation, with partly recycled minor evaporites. Of special interest is Site 652, where the thickness of the (probable) Messinian is 530 m. Sedimentary characters indicate a permanently subaqueous but nonmarine environment, with turbidites accumulating in a rapidly subsiding basin. According to the model proposed, this basin was fed by continental waters during times of maximum evaporitic draw-down, with temporary marine incursions from the west or southwest when the water level was higher. A basement ridge separated the evaporating pond from this endoreic lake located on the opposite (eastern) margin of the Tyrrhenian Basin, which was then limited to its western part. Post-Messinian reactivation of the "Faglia centrale" is necessary to account for the inversion of the relief.

CO2 soil flux baseline at the technological development plant for CO2 injection at Hontomin (Burgos, Spain)

From the end of 2013 and during the following two years, 20 kt of CO2sc are planned to be injected in a saline reservoir (1500 m depth) at the Hontomín site (NE Spain). The target aquifers are Lower Jurassic limestone formations which are sealed by Lower Cretaceous clay units at the Hontomín site (NE Spain). The injection of CO2 is part of the activities committed in the Technology Development phase of the EC-funded OXYCFB300 project (European Energy Program for Recovery – EEPR, http://www.compostillaproject.eu), which include CO2 injection strategies, risk assessment, and testing and validating monitoring methodologies and techniques. Among the monitoring works, the project is intended to prove that present-day technology is able to monitor the evolution of injected CO2 in the reservoir and to detect potential leakage. One of the techniques is the measurement of CO2 flux at the soil–atmosphere interface, which includes campaigns before, during and after the injection operations. In this work soil CO2 flux measurements in the vicinity of oil borehole, drilled in the eighties and named H-1 to H-4, and injection and monitoring wells were performed using an accumulation chamber equipped with an IR sensor. Seven surveys were carried out from November 2009 to summer 2011. More than 4000 measurements were used to determine the baseline flux of CO2 and its seasonal variations. The measured values were low (from 5 to 13 g m−2 day−1) and few outliers were identified, mainly located close to the H-2 oil well. Nevertheless, these values cannot be associated to a deep source of CO2, being more likely related to biological processes, i.e. soil respiration. No anomalies were recognized close to the deep fault system (Ubierna Fault) detected by geophysical investigations. There, the CO2 flux is indeed as low as other measurement stations. CO2 fluxes appear to be controlled by the biological activity since the lowest values were recorded during autumn-winter seasons and they tend to increase in warm periods. Two reference CO2 flux values (UCL50 of 5 g m−2 d−1 for non-ploughed areas in autumn–winter seasons and 3.5 and 12 g m−2 d−1 for in ploughed and non-ploughed areas, respectively, in spring–summer time, and UCL99 of 26 g m−2 d−1 for autumn–winter in not-ploughed areas and 34 and 42 g m−2 d−1 for spring–summer in ploughed and not-ploughed areas, respectively) were calculated. Fluxes higher than these reference values could be indicative of possible leakage during the operational and post-closure stages of the storage project.

Seismic Risk Scenarios in Puerto Principe (Haiti). A Tool for Reconstruction and Emergency Planning

The 12 January 2010, an earthquake hit the city of Port-au-Prince, capital of Haiti. The earthquake reached a magnitude Mw 7.0 and the epicenter was located near the town of Léogâne, approximately 25 km west of the capital. The earthquake occurred in the boundary region separating the Caribbean plate and the North American plate. This plate boundary is dominated by left-lateral strike slip motion and compression, and accommodates about 20 mm/y slip, with the Caribbean plate moving eastward with respect to the North American plate (DeMets et al., 2000). Initially the location and focal mechanism of the earthquake seemed to involve straightforward accommodation of oblique relative motion between the Caribbean and North American plates along the Enriquillo-Plantain Garden fault system (EPGFZ), however Hayes et al., (2010) combined seismological observations, geologic field data and space geodetic measurements to show that, instead, the rupture process involved slip on multiple faults. Besides, the authors showed that remaining shallow shear strain will be released in future surface-rupturing earthquakes on the EPGFZ. In December 2010, a Spanish cooperation project financed by the Politechnical University of Madrid started with a clear objective: Evaluation of seismic hazard and risk in Haiti and its application to the seismic design, urban planning, emergency and resource management. One of the tasks of the project was devoted to vulnerability assessment of the current building stock and the estimation of seismic risk scenarios. The study was carried out by following the capacity spectrum method as implemented in the software SELENA (Molina et al., 2010). The method requires a detailed classification of the building stock in predominant building typologies (according to the materials in the structure and walls, number of stories and age of construction) and the use of the building (residential, commercial, etc.). Later, the knowledge of the soil characteristics of the city and the simulation of a scenario earthquake will provide the seismic risk scenarios (damaged buildings). The initial results of the study show that one of the highest sources of uncertainties comes from the difficulty of achieving a precise building typologies classification due to the craft construction without any regulations. Also it is observed that although the occurrence of big earthquakes usually helps to decrease the vulnerability of the cities due to the collapse of low quality buildings and the reconstruction of seismically designed buildings, in the case of Port-au-Prince the seismic risk in most of the districts remains high, showing very vulnerable areas. Therefore the local authorities have to drive their efforts towards the quality control of the new buildings, the reinforcement of the existing building stock, the establishment of seismic normatives and the development of emergency planning also through the education of the population.

Estrategias de monitorización de CO2 y otros gases en los estudios de análogos naturales

La Universidad Politécnica de Madrid (UPM) y la Università degli Studi di Firenze (UniFi), bajo la coordinación técnica de AMPHOS21, participan desde 2009 en el proyecto de investigación “Estrategias de Monitorización de CO2 y otros gases en el estudio de Análogos Naturales”, financiado por la Fundación Ciudad de la Energía (CIUDEN) en el marco del Proyecto Compostilla OXYCFB300 (http://www.compostillaproject.eu), del Programa “European Energy Program for Recovery - EEPR”. El objetivo principal del proyecto fue el desarrollo y puesta a punto de metodologías de monitorización superficiales para su aplicación en el seguimiento y control de los emplazamientos donde se realice el almacenamiento geológico de CO2, analizando técnicas que permitan detectar y cuantificar las posibles fugas de CO2 a la atmósfera. Los trabajos se realizaron tanto en análogos naturales (españoles e italianos) como en la Planta de Desarrollo Tecnológico de Almacenamiento de CO2 de Hontomín. Las técnicas analizadas se centran en la medición de gases y aguas superficiales (de escorrentía y manantiales). En cuanto a la medición de gases se analizó el flujo de CO2 que emana desde el suelo a la atmósfera y la aplicabilidad de trazadores naturales (como el radón) para la detección e identificación de las fugas de CO2. En cuanto al análisis químico de las aguas se analizaron los datos geoquímicos e isotópicos y los gases disueltos en las aguas de los alrededores de la PDT de Hontomín, con objeto de determinar qué parámetros son los más apropiados para la detección de una posible migración del CO2 inyectado, o de la salmuera, a los ambientes superficiales. Las medidas de flujo de CO2 se realizaron con la técnica de la cámara de acúmulo. A pesar de ser una técnica desarrollada y aplicada en diferentes ámbitos científicos se estimó necesario adaptar un protocolo de medida y de análisis de datos a las características específicas de los proyectos de captura y almacenamiento de CO2 (CAC). Donde los flujos de CO2 esperados son bajos y en caso de producirse una fuga habrá que detectar pequeñas variaciones en los valores flujo con un “ruido” en la señal alto, debido a actividad biológica en el suelo. La medida de flujo de CO2 mediante la técnica de la cámara de acúmulo se puede realizar sin limpiar la superficie donde se coloca la cámara o limpiando y esperando al reequilibrio del flujo después de la distorsión al sistema. Sin embargo, los resultados obtenidos después de limpiar y esperar muestran menor dispersión, lo que nos indica que este procedimiento es el mejor para la monitorización de los complejos de almacenamiento geológico de CO2. El protocolo de medida resultante, utilizado para la obtención de la línea base de flujo de CO2 en Hontomín, sigue los siguiente pasos: a) con una espátula se prepara el punto de medición limpiando y retirando el recubrimiento vegetal o la primera capa compacta de suelo, b) se espera un tiempo para la realización de la medida de flujo, facilitando el reequilibrio del flujo del gas tras la alteración provocada en el suelo y c) se realiza la medida de flujo de CO2. Una vez realizada la medición de flujo de CO2, y detectada si existen zonas de anomalías, se debe estimar la cantidad de CO2 que se está escapando a la atmósfera (emanación total), con el objetivo de cuantificar la posible fuga. Existen un amplio rango de metodologías para realizar dicha estimación, siendo necesario entender cuáles son las más apropiadas para obtener el valor más representativo del sistema. En esta tesis se comparan seis técnicas estadísticas: media aritmética, estimador insegado de la media (aplicando la función de Sichel), remuestreo con reemplazamiento (bootstrap), separación en diferentes poblaciones mediante métodos gráficos y métodos basados en criterios de máxima verosimilitud, y la simulación Gaussiana secuencial. Para este análisis se realizaron ocho campañas de muestreo, tanto en la Planta de Desarrollo Tecnológico de Hontomón como en análogos naturales (italianos y españoles). Los resultados muestran que la simulación Gaussiana secuencial suele ser el método más preciso para realizar el cálculo, sin embargo, existen ocasiones donde otros métodos son más apropiados. Como consecuencia, se desarrolla un procedimiento de actuación para seleccionar el método que proporcione el mejor estimador. Este procedimiento consiste, en primer lugar, en realizar un análisis variográfico. Si existe una autocorrelación entre los datos, modelizada mediante el variograma, la mejor técnica para calcular la emanación total y su intervalo de confianza es la simulación Gaussiana secuencial (sGs). Si los datos son independientes se debe comprobar la distribución muestral, aplicando la media aritmética o el estimador insesgado de la media (Sichel) para datos normales o lognormales respectivamente. Cuando los datos no son normales o corresponden a una mezcla de poblaciones la mejor técnica de estimación es la de remuestreo con reemplazamiento (bootstrap). Siguiendo este procedimiento el máximo valor del intervalo de confianza estuvo en el orden del ±20/25%, con la mayoría de valores comprendidos entre ±3,5% y ±8%. La identificación de las diferentes poblaciones muestrales en los datos de flujo de CO2 puede ayudar a interpretar los resultados obtenidos, toda vez que esta distribución se ve afectada por la presencia de varios procesos geoquímicos como, por ejemplo, una fuente geológica o biológica del CO2. Así pues, este análisis puede ser una herramienta útil en el programa de monitorización, donde el principal objetivo es demostrar que no hay fugas desde el reservorio a la atmósfera y, si ocurren, detectarlas y cuantificarlas. Los resultados obtenidos muestran que el mejor proceso para realizar la separación de poblaciones está basado en criterios de máxima verosimilitud. Los procedimientos gráficos, aunque existen pautas para realizarlos, tienen un cierto grado de subjetividad en la interpretación de manera que los resultados son menos reproducibles. Durante el desarrollo de la tesis se analizó, en análogos naturales, la relación existente entre el CO2 y los isótopos del radón (222Rn y 220Rn), detectándose en todas las zonas de emisión de CO2 una relación positiva entre los valores de concentración de 222Rn en aire del suelo y el flujo de CO2. Comparando la concentración de 220Rn con el flujo de CO2 la relación no es tan clara, mientras que en algunos casos aumenta en otros se detecta una disminución, hecho que parece estar relacionado con la profundidad de origen del radón. Estos resultados confirmarían la posible aplicación de los isótopos del radón como trazadores del origen de los gases y su aplicación en la detección de fugas. Con respecto a la determinación de la línea base de flujo CO2 en la PDT de Hontomín, se realizaron mediciones con la cámara de acúmulo en las proximidades de los sondeos petrolíferos, perforados en los ochenta y denominados H-1, H-2, H-3 y H-4, en la zona donde se instalarán el sondeo de inyección (H-I) y el de monitorización (H-A) y en las proximidades de la falla sur. Desde noviembre de 2009 a abril de 2011 se realizaron siete campañas de muestreo, adquiriéndose más de 4.000 registros de flujo de CO2 con los que se determinó la línea base y su variación estacional. Los valores obtenidos fueron bajos (valores medios entre 5 y 13 g•m-2•d-1), detectándose pocos valores anómalos, principalmente en las proximidades del sondeo H-2. Sin embargo, estos valores no se pudieron asociar a una fuente profunda del CO2 y seguramente estuvieran más relacionados con procesos biológicos, como la respiración del suelo. No se detectaron valores anómalos cerca del sistema de fracturación (falla Ubierna), toda vez que en esta zona los valores de flujo son tan bajos como en el resto de puntos de muestreo. En este sentido, los valores de flujo de CO2 aparentemente están controlados por la actividad biológica, corroborado al obtenerse los menores valores durante los meses de otoño-invierno e ir aumentando en los periodos cálidos. Se calcularon dos grupos de valores de referencia, el primer grupo (UCL50) es 5 g•m-2•d-1 en las zonas no aradas en los meses de otoño-invierno y 3,5 y 12 g•m-2•d-1 en primavera-verano para zonas aradas y no aradas, respectivamente. El segundo grupo (UCL99) corresponde a 26 g•m-2•d- 1 durante los meses de otoño-invierno en las zonas no aradas y 34 y 42 g•m-2•d-1 para los meses de primavera-verano en zonas aradas y no aradas, respectivamente. Flujos mayores a estos valores de referencia podrían ser indicativos de una posible fuga durante la inyección y posterior a la misma. Los primeros datos geoquímicos e isotópicos de las aguas superficiales (de escorrentía y de manantiales) en el área de Hontomín–Huermeces fueron analizados. Los datos sugieren que las aguas estudiadas están relacionadas con aguas meteóricas con un circuito hidrogeológico superficial, caracterizadas por valores de TDS relativamente bajos (menor a 800 mg/L) y una fácie hidrogeoquímica de Ca2+(Mg2+)-HCO3 −. Algunas aguas de manantiales se caracterizan por concentraciones elevadas de NO3 − (concentraciones de hasta 123 mg/l), lo que sugiere una contaminación antropogénica. Se obtuvieron concentraciones anómalas de of Cl−, SO4 2−, As, B y Ba en dos manantiales cercanos a los sondeos petrolíferos y en el rio Ubierna, estos componentes son probablemente indicadores de una posible mezcla entre los acuíferos profundos y superficiales. El estudio de los gases disueltos en las aguas también evidencia el circuito superficial de las aguas. Estando, por lo general, dominado por la componente atmosférica (N2, O2 y Ar). Sin embargo, en algunos casos el gas predominante fue el CO2 (con concentraciones que llegan al 63% v/v), aunque los valores isotópicos del carbono (<-17,7 ‰) muestran que lo más probable es que esté relacionado con un origen biológico. Los datos geoquímicos e isotópicos de las aguas superficiales obtenidos en la zona de Hontomín se pueden considerar como el valor de fondo con el que comparar durante la fase operacional, la clausura y posterior a la clausura. En este sentido, la composición de los elementos mayoritarios y traza, la composición isotópica del carbono del CO2 disuelto y del TDIC (Carbono inorgánico disuelto) y algunos elementos traza se pueden considerar como parámetros adecuados para detectar la migración del CO2 a los ambientes superficiales. ABSTRACT Since 2009, a group made up of Universidad Politécnica de Madrid (UPM; Spain) and Università degli Studi Firenze (UniFi; Italy) has been taking part in a joint project called “Strategies for Monitoring CO2 and other Gases in Natural analogues”. The group was coordinated by AMPHOS XXI, a private company established in Barcelona. The Project was financially supported by Fundación Ciudad de la Energía (CIUDEN; Spain) as a part of the EC-funded OXYCFB300 project (European Energy Program for Recovery -EEPR-; www.compostillaproject.eu). The main objectives of the project were aimed to develop and optimize analytical methodologies to be applied at the surface to Monitor and Verify the feasibility of geologically stored carbon dioxide. These techniques were oriented to detect and quantify possible CO2 leakages to the atmosphere. Several investigations were made in natural analogues from Spain and Italy and in the Tecnchnological Development Plant for CO2 injection al Hontomín (Burgos, Spain). The studying techniques were mainly focused on the measurements of diffuse soil gases and surface and shallow waters. The soil-gas measurements included the determination of CO2 flux and the application to natural trace gases (e.g. radon) that may help to detect any CO2 leakage. As far as the water chemistry is concerned, geochemical and isotopic data related to surface and spring waters and dissolved gases in the area of the PDT of Hontomín were analyzed to determine the most suitable parameters to trace the migration of the injected CO2 into the near-surface environments. The accumulation chamber method was used to measure the diffuse emission of CO2 at the soil-atmosphere interface. Although this technique has widely been applied in different scientific areas, it was considered of the utmost importance to adapt the optimum methodology for measuring the CO2 soil flux and estimating the total CO2 output to the specific features of the site where CO2 is to be stored shortly. During the pre-injection phase CO2 fluxes are expected to be relatively low where in the intra- and post-injection phases, if leakages are to be occurring, small variation in CO2 flux might be detected when the CO2 “noise” is overcoming the biological activity of the soil (soil respiration). CO2 flux measurements by the accumulation chamber method could be performed without vegetation clearance or after vegetation clearance. However, the results obtained after clearance show less dispersion and this suggests that this procedure appears to be more suitable for monitoring CO2 Storage sites. The measurement protocol, applied for the determination of the CO2 flux baseline at Hontomín, has included the following steps: a) cleaning and removal of both the vegetal cover and top 2 cm of soil, b) waiting to reduce flux perturbation due to the soil removal and c) measuring the CO2 flux. Once completing the CO2 flux measurements and detected whether there were anomalies zones, the total CO2 output was estimated to quantify the amount of CO2 released to the atmosphere in each of the studied areas. There is a wide range of methodologies for the estimation of the CO2 output, which were applied to understand which one was the most representative. In this study six statistical methods are presented: arithmetic mean, minimum variances unbiased estimator, bootstrap resample, partitioning of data into different populations with a graphical and a maximum likelihood procedures, and sequential Gaussian simulation. Eight campaigns were carried out in the Hontomín CO2 Storage Technology Development Plant and in natural CO2 analogues. The results show that sequential Gaussian simulation is the most accurate method to estimate the total CO2 output and the confidential interval. Nevertheless, a variety of statistic methods were also used. As a consequence, an application procedure for selecting the most realistic method was developed. The first step to estimate the total emanation rate was the variogram analysis. If the relation among the data can be explained with the variogram, the best technique to calculate the total CO2 output and its confidence interval is the sequential Gaussian simulation method (sGs). If the data are independent, their distribution is to be analyzed. For normal and log-normal distribution the proper methods are the arithmetic mean and minimum variances unbiased estimator, respectively. If the data are not normal (log-normal) or are a mixture of different populations the best approach is the bootstrap resampling. According to these steps, the maximum confidence interval was about ±20/25%, with most of values between ±3.5% and ±8%. Partitioning of CO2 flux data into different populations may help to interpret the data as their distribution can be affected by different geochemical processes, e.g. geological or biological sources of CO2. Consequently, it may be an important tool in a monitoring CCS program, where the main goal is to demonstrate that there are not leakages from the reservoir to the atmosphere and, if occurring, to be able to detect and quantify it. Results show that the partitioning of populations is better performed by maximum likelihood criteria, since graphical procedures have a degree of subjectivity in the interpretation and results may not be reproducible. The relationship between CO2 flux and radon isotopes (222Rn and 220Rn) was studied in natural analogues. In all emissions zones, a positive relation between 222Rn and CO2 was observed. However, the relationship between activity of 220Rn and CO2 flux is not clear. In some cases the 220Rn activity indeed increased with the CO2 flux in other measurements a decrease was recognized. We can speculate that this effect was possibly related to the route (deep or shallow) of the radon source. These results may confirm the possible use of the radon isotopes as tracers for the gas origin and their application in the detection of leakages. With respect to the CO2 flux baseline at the TDP of Hontomín, soil flux measurements in the vicinity of oil boreholes, drilled in the eighties and named H-1 to H-4, and injection and monitoring wells were performed using an accumulation chamber. Seven surveys were carried out from November 2009 to summer 2011. More than 4,000 measurements were used to determine the baseline flux of CO2 and its seasonal variations. The measured values were relatively low (from 5 to 13 g•m-2•day-1) and few outliers were identified, mainly located close to the H-2 oil well. Nevertheless, these values cannot be associated to a deep source of CO2, being more likely related to biological processes, i.e. soil respiration. No anomalies were recognized close to the deep fault system (Ubierna Fault) detected by geophysical investigations. There, the CO2 flux is indeed as low as other measurement stations. CO2 fluxes appear to be controlled by the biological activity since the lowest values were recorded during autumn-winter seasons and they tend to increase in warm periods. Two reference CO2 flux values (UCL50 of 5 g•m-2•d-1 for non-ploughed areas in autumn-winter seasons and 3.5 and 12 g•m-2•d-1 for in ploughed and non-ploughed areas, respectively, in spring-summer time, and UCL99 of 26 g•m-2•d-1 for autumn-winter in not-ploughed areas and 34 and 42 g•m-2•d-1 for spring-summer in ploughed and not-ploughed areas, respectively, were calculated. Fluxes higher than these reference values could be indicative of possible leakage during the operational and post-closure stages of the storage project. The first geochemical and isotopic data related to surface and spring waters and dissolved gases in the area of Hontomín–Huermeces (Burgos, Spain) are presented and discussed. The chemical and features of the spring waters suggest that they are related to a shallow hydrogeological system as the concentration of the Total Dissolved Solids approaches 800 mg/L with a Ca2+(Mg2+)-HCO3 − composition, similar to that of the surface waters. Some spring waters are characterized by relatively high concentrations of NO3 − (up to 123 mg/L), unequivocally suggesting an anthropogenic source. Anomalous concentrations of Cl−, SO4 2−, As, B and Ba were measured in two springs, discharging a few hundred meters from the oil wells, and in the Rio Ubierna. These contents are possibly indicative of mixing processes between deep and shallow aquifers. The chemistry of the dissolved gases also evidences the shallow circuits of the Hontomín– Huermeces, mainly characterized by an atmospheric source as highlighted by the contents of N2, O2, Ar and their relative ratios. Nevertheless, significant concentrations (up to 63% by vol.) of isotopically negative CO2 (<−17.7‰ V-PDB) were found in some water samples, likely related to a biogenic source. The geochemical and isotopic data of the surface and spring waters in the surroundings of Hontomín can be considered as background values when intra- and post-injection monitoring programs will be carried out. In this respect, main and minor solutes, the isotopic carbon of dissolved CO2 and TDIC (Total Dissolved Inorganic Carbon) and selected trace elements can be considered as useful parameters to trace the migration of the injected CO2 into near-surface environments.

Aceleraciones registradas y calculadas del sismo del 12 de agosto de 2014 en Quito.

El 12 de agosto de 2014, se registró un sismo de magnitud 5.1, a una profundidad focal de 4 km., en el segmento de falla Bellavista Catequilla, el mismo que fue registrado en 8 estaciones localizadas en la ciudad de Quito. Estas se encuentran ubicadas a distancias epicentrales entre 12 y 19 km. En este artículo se comparan las aceleraciones máximas obtenidas en campo libre, con las que se obtienen al emplear las ecuaciones de movimientos fuertes de Campbell y Borzognia (2013) y el de Zhao et al. (2006). Para ello previamente se determina un plano de ruptura del sismo, utilizando las ecuaciones propuestas por Leonard (2010) y la geometría de las fallas ciegas propuestas por Alvarado (2014). ABSTRACT: On August 12 th 2014, a magnitude 5.1 earthquake occurred at a depth of 4 km, in the Bellavista Catequilla fault segment. This event was recorded by 8 strong-motion stations located between 12 and 19 km from the epicenter, in the city of Quito. In this article, the maximum ground accelerations recorded in free field are compared with the accelerations estimated using the models by Campbell y Borzognia (2013) and Zh ao et al. (2006). To this end, the earthquake rupture plane is determined using the equations proposed by Leonard (2010) and the geometry of the blind fault system of Quito proposed by Alvarado (2014).

Intermediate-term earthquake prediction.

An earthquake of magnitude M and linear source dimension L(M) is preceded within a few years by certain patterns of seismicity in the magnitude range down to about (M - 3) in an area of linear dimension about 5L-10L. Prediction algorithms based on such patterns may allow one to predict approximately 80% of strong earthquakes with alarms occupying altogether 20-30% of the time-space considered. An area of alarm can be narrowed down to 2L-3L when observations include lower magnitudes, down to about (M - 4). In spite of their limited accuracy, such predictions open a possibility to prevent considerable damage. The following findings may provide for further development of prediction methods: (i) long-range correlations in fault system dynamics and accordingly large size of the areas over which different observed fields could be averaged and analyzed jointly, (ii) specific symptoms of an approaching strong earthquake, (iii) the partial similarity of these symptoms worldwide, (iv) the fact that some of them are not Earth specific: we probably encountered in seismicity the symptoms of instability common for a wide class of nonlinear systems.

Radon 222 excess measured on water bottle samples during HEINCKE cruise HE153

In the years 2000 and 2001 we measured methane concentrations exceeding up to two orders of magnitude the equilibrium with the atmosphere in the water column on the SW-Spitsbergen continental shelf. This methane anomaly extended from its centre on the shelf westwards over the upper slope and eastwards well into the inner basins of the two southernmost Spitsbergen fjords, the Hornsundfjord and the van Mijenfjord. Methane concentrations and stable carbon isotopic ratios varied between 2 and 240 nM, and between -53 per mill and -20 per mill VPDB, respectively. Methane in high concentrations was depleted in 13C whereas in low concentrations d13CCH4 values were highly variable. On the continental shelf we found that methane discharged from seeps on top of sandy and gravelly banks is isotopically heavier than methane escaping from troughs filled with silty and clayey sediments. These distinct isotopic signatures suggest that methane is gently released from several inter-granular seepages or micro-seepages widely spread over the shelf. A potential migration path for thermogenic or hydrate methane may be the Hornsund Fracture Zone, a south-north running reactivated fault system created by stretching of the continental crust. After discharge into the water column, local water currents fed by Atlantic water, coastal water, and freshwater outflows from the fjords further determine pathways and fate of the methane. We used d18Owater and 222Rn data to trace origin and advection of the local water masses and water mixing processes. Methane spreads predominantly along pycnoclines and by vertical mixing. During transport methane is influenced simultaneously by oxidation and dilution, as well as loss into the atmosphere. Together these processes cause the spatial variability of the anomaly and heterogeneity in d13CCH4 in this polar shelf environment.

40Ar/39Ar constraints on a temporal link between gold mineralization, magmatism, and continental margin transtension in the Jiaodong Gold Province, eastern China

The Jiaodong gold province is the largest gold repository in China. Both mineralization and granitoid hosts are spatially related to the crustal-scale Tan-Lu strike-slip fault system, which developed along the Mesozoic continental margin in eastern China. A series of Ar-40/Ar-39 laser incremental heating analyses of hydrothermal sericite/muscovite from three major gold deposits (Jiaojia, Xincheng, and Wangershan) and igneous biotite from the granodiorite hosts were performed to establish a possible temporal link between gold mineralization, magmatism, and movement along the Tan-Lu fault zone. Magmatic biotite crystals yield well-defined and concordant plateau ages between 124.5+/-0.4 Ma and 124.0+/-0.4 Ma (2sigma), whereas sericite and muscovite samples (a total of 30 single separates) give reproducible plateau ages ranging from 121.0+/-0.4 Ma to 119.2+/-0.2 Ma (2sigma). An integration of our Ar-40/Ar-39 results with age data from other major gold deposits in Jiaodong demonstrates that widespread gold mineralization occurred contemporaneously during a 2-3-m.yr. period. Most gold deposits show intimate spatial associations with abundant mafic to intermediate dikes. The mafic dikes have K-Ar ages of 123.5-119.6 Ma, in excellent agreement with those of the gold deposits. These newly obtained Ar-40/Ar-39 ages, in combination with other independent geological and geochronological data on granodioritic intrusions (130-126 Ma), volcanic rocks (1243.6-114.7 Ma), and deformed rocks within strike-slip faults (132-120 Ma) in Jiaodong or adjacent areas, also support the idea that gold mineralization postdated the granodioritic magmatism but was contemporaneous with mafic magmatism and volcanism, all controlled by the transtensional motion along the Tan-Lu fault in the Early Cretaceous.

Karst hazard analysis towards the development of predictive karst models for southern Ontario

An investigation into karst hazard in southern Ontario has been undertaken with the intention of leading to the development of predictive karst models for this region. The reason these are not currently feasible is a lack of sufficient karst data, though this is not entirely due to the lack of karst features. Geophysical data was collected at Lake on the Mountain, Ontario as part of this karst investigation. This data was collected in order to validate the long-standing hypothesis that Lake on the Mountain was formed from a sinkhole collapse. Sub-bottom acoustic profiling data was collected in order to image the lake bottom sediments and bedrock. Vertical bedrock features interpreted as solutionally enlarged fractures were taken as evidence for karst processes on the lake bottom. Additionally, the bedrock topography shows a narrower and more elongated basin than was previously identified, and this also lies parallel to a mapped fault system in the area. This suggests that Lake on the Mountain was formed over a fault zone which also supports the sinkhole hypothesis as it would provide groundwater pathways for karst dissolution to occur. Previous sediment cores suggest that Lake on the Mountain would have formed at some point during the Wisconsinan glaciation with glacial meltwater and glacial loading as potential contributing factors to sinkhole development. A probabilistic karst model for the state of Kentucky, USA, has been generated using the Weights of Evidence method. This model is presented as an example of the predictive capabilities of these kind of data-driven modelling techniques and to show how such models could be applied to karst in Ontario. The model was able to classify 70% of the validation dataset correctly while minimizing false positive identifications. This is moderately successful and could stand to be improved. Finally, suggestions to improving the current karst model of southern Ontario are suggested with the goal of increasing investigation into karst in Ontario and streamlining the reporting system for sinkholes, caves, and other karst features so as to improve the current Ontario karst database.

Tectonic expression of an active slab tear from high-resolution seismic and bathymetric data offshore Sicily (Ionian Sea)

Subduction of a narrow slab of oceanic lithosphere beneath a tightly curved orogenic arc requires the presence of at least one lithospheric scale tear fault. While the Calabrian subduction beneath southern Italy is considered to be the type example of this geodynamic setting, the geometry, kinematics and surface expression of the associated lateral, slab tear fault offshore eastern Sicily remain controversial. Results from a new marine geophysical survey conducted in the Ionian Sea, using high-resolution bathymetry and seismic profiling reveal active faulting at the seafloor within a 140 km long, two-branched fault system near Alfeo Seamount. The previously unidentified 60 km long NW trending North Alfeo Fault system shows primarily strike-slip kinematics as indicated by the morphology and steep-dipping transpressional and transtensional faults. Available earthquake focal mechanisms indicate dextral strike-slip motion along this fault segment. The 80 km long SSE trending South Alfeo fault system is expressed by one or two steeply dipping normal faults, bounding the western side of a 500+ m thick, 5 km wide, elongate, syntectonic Plio-Quaternary sedimentary basin. Both branches of the fault system are mechanically capable of generating magnitude 6-7 earthquakes like those that struck eastern Sicily in 1169, 1542, and 1693.

Geologia, petrologia, geocronologia e mineralizações sulfetadas do complexo ézio, província mineral de carajás, Brasil

Dissertação (mestrado)—Universidade de Brasília, Instituto de Geociências, Pós-Graduação em Geologia, 2015.

El Estribo Volcanic Complex: Evolution from a shield volcano to a cinder cone, Pátzcuaro Lake, Michoacán, México

El Estribo Volcanic Complex (EVC) is located in the northern part of the Michoacán–Guanajuato Volcanic Field within the Trans-Mexican Volcanic Belt (TMVB). El Estribo is located at the southern edge of the E-W Pátzcuaro fault that belongs to the Pátzcuaro-Jarácuaro graben, a western extension of the E-W Morelia–Acambay fault system. Stratigraphy, geochronology, chemistry, and mineral assemblages suggest that the volcanic complex was constructed in two periods separated by a ~ 100 ka volcanic hiatus: a) emission of lava flows that constructed a shield volcano between 126 ka, and b) mixed phreatomagmatic to Strombolian activity that formed a cinder cone ~ 28 ka. The magmas that fed these monogenetic volcanoes were able to use the same feeding system. The cinder cone itself was constructed by Strombolian fallouts and remobilized scoria beds, followed by an erosion period, and by a mixed phreatomagmatic to magmatic phase (Strombolian fallouts ending with lava flows). Soft-sedimentary deformation of beds and impact sags, cross-bedding, as well as pitting and hydrothermal cracks found in particles support the phreatomagmatic phase. The erupted magmas through time ejected basaltic andesitic lava flows (56.21–58.88% SiO2) that built the shield volcano and then basaltic andesitic scoria (57.65–59.05% SiO2) that constructed the cinder cone. Although they used the same feeding system, the geochemical data and the mineral chemistry of the magmas indicate that the shield volcano and the cinder cone were fed by different magma batches erupted thousands of years apart. Therefore, the location of El Estribo Volcanic Complex along an E-W fault that has generated two sector collapses of the shield volcano to the north may be directly linked to this complex redistribution of the magmatic paths to the surface. Our findings show that magmatic feeding systems within monogenetic volcanic fields could be long lived, questioning the classic view of the monogenetic nature of their volcanoes and yielding information about the potential volcanic risk of these settings, usually considered risk-free.

Tectonics of Central and Eastern California, Late Cretaceous to Modern

The Late Cretaceous to Modern tectonic evolution of central and eastern California has been studied for many decades, with published work generally focusing on specific geographic areas and time periods. The resulting literature leaves the reader, whether graduate student, faculty member, or layperson, wondering what a coherently integrated tectonic evolution might look like, or if it would be at all possible to undertake such a task. This question is the common thread weaving together the four studies presented in this work. Each of the individual chapters is targeted at a specific location and time period which I have identified as a critical yet missing link in piecing together a coherent regional tectonic story. In the first chapter, we re-discover a set of major west down normal faults running along the western slope of the southern Sierra, the western Sierra fault system (WSFS). We show that one of these faults was offset by roughly a kilometer in Eocene time, and that this activity directly resulted in the incision of much of the relief present in modern Kings Canyon. The second chapter is a basement landscape and thermochronometric study of the hanging wall of the WSFS. New data from this study area provide a significant westward expansion of basement thermochronometric data from the southern Sierra Nevada batholith. Thermal modeling results of these data provide critical new constraints on the early exhumation of the Sierra Nevada batholith, and in the context of the results from Chapter I, allow us to piece together a coherent chronology of tectonic forcings and landscape evolution for the southern Sierra Nevada. In the third chapter, I present a study of the surface rupture of the 1999 Hector Mine earthquake, a dextral strike slip event on a fault in the Eastern California Shear Zone (ECSZ). New constraints on the active tectonics in ECSZ will help future studies better resolve the enigmatic mismatch between geologic slip rates and geodetically determined regional rates. Chapter IV is a magnetostratigraphic pilot study of the Paleocene Goler Formation. This study provides strong evidence that continued investigation will yield new constraints on the depositional age of the only fossil-bearing Paleocene terrestrial deposit on the west coast of North America. Each of these studies aims to provide important new data at critical missing links in the tectonic evolution of central and eastern California.

Fault-Location System for Multiterminal Transmission Lines

This research presents the development and implementation in a computational routine of algorithms for fault location in multiterminal transmission lines. These algorithms are part of a fault-location system, which is capable of correctly identifying the fault point based on voltage and current phasor quantities, calculated by using measurements of voltage and current signals from intelligent electronic devices, located on the transmission-line terminals. The algorithms have access to the electrical parameters of the transmission lines and to information about the transformers loading and their connection type. This paper also presents the development of phase component models for the power system elements used by the fault-location algorithms.