This study aims to determine the chemical (anion-cation) and isotopic compositions (&amp / #948 / 18O-&amp / #948 / D-3H) of the geothermal waters along the North Anatolian Fault Zone (NAFZ) and highlight any possible seismicity-induced temporal variations during the course of two years (2002-2003) monitoring programme. The geothermal sites are alligned along a 800 km transect of the NAFZ and are, from west to east, Yalova, Efteni, Bolu, Mudurnu, Seben, KurSunlu, Hamam&ouml / z&uuml / , G&ouml / zlek and ReSadiye. The thermal waters of NAFZ are dominantly Na-HCO3, whereas the cold waters are dominantly Ca-HCO3 in character. The highest temperature (72.3&amp / #61616 / C) is recorded in Seben. The hot waters are slightly acidic to alkaline in character with pH values ranging between 5.92-7.97, while the cold waters are comparatively more alkaline with pH values between 6.50-8.83. Both hot and the cold waters are meteoric in origin. The hot waters have lower &amp / #948 / 18O-&amp / #948 / D and tritium values suggesting higher recharge altitudes for aquifers and longer residence times for waters, respectively, in the geothermal system (compared to the cold waters). Temporal variations are detected in both ionic and isotopic compositions of the cold and the hot waters, and these reflect seasonal variations for cold and seismicity-induced variations for hot waters. Although no major earthquakes (M&gt / 5) occurred along the NAFZ during the monitoring period, temporal variations recorded in Cl and 3H, and to a lesser extent in Ca and SO4 contents seem to correlate with seismicity along the NAFZ. In this respect, Yalova field deserves the particular attention since seismicity induced variations were better recorded in this field.

Thesis (M.S.)--Miami University, Dept. of Geology, 2005. / Title from first page of PDF document. Document formatted into pages; contains [1], v, 72 p., [64] plates : ill. Includes bibliographical references (p. 65-71).

This thesis project was conducted in connection with the project, Stockholm’s future sewer pipeline, which is a planned sewer pipe that will run through a tunnel from western to southern Stockholm. This tunnel will pass under Lake Mälaren between Eolshäll and Smedslätten, where there are two faults indicated on the geological map, that could affect the tunnelling and create risks during the construction. Geophysical- and water-loss measurements along with core drilling have been carried out in the area. The objectives of this thesis are to create a structural and engineering geological understanding of the passage beneath Lake Mälaren based on drill core mapping, field work, data from previous investi-gations and 2D-models of the tunnel excavation both within and outside the indicated fault zone. The core mapping supports the existence of one fault zone, which is indicated on the geological map supported by water-losses at several places along the drill core as well as core losses. Field work indi-cated the existence of a conjugate fracture sets.The 2D-models present plastic behaviour of the rock in the fault zone as the worst case scenario during excavation with the highest deformation displacement. The excavation procedure and the tunnel form also play a significant role. Since this thesis highlights some significant risks and problems that can occur during tunnelling, its findings may be useful during the tunnel construction. / Denna uppsats är skriven med koppling till projektet, Stockholms framtida avloppsledning, vilket inkluderar en ny tunnel för transport av avloppsvatten från västra till södra Stockholm. Tunneln kommer att passera under Mälaren mellan Smedslätten och Eolshäll, där det är två förkastningar indikerade på geologiska kartor som kan orsaka stora risker för byggnationen av tunneln. Geofysiska mätningar, kärnborrning och vattenförlustmätning har tidigare utförts i området. Målen för denna uppsats är att skapa en geologisk- och bergmekanisk förståelse för tunnelpassagen under Mälaren utifrån kärnkartering, fältarbete, data från tidigare undersökningar och 2D-modeller av tunneluttag i den indikerade zonen och utanför. Kärnkarteringen stödjer existensen av en förkastningszon som finns på den geologiska kartan. Flertalet vattenförluster är indikerade längs med hela kärnan tillsammans med en del förekomster av kärnförluster. Fältarbetet indikerar på förekomst av ett konjugerande sprickset. 2D-modeller över tunneln visade att olika egenskaper på berget samt hur uttaget av tunneln sker har betydelse för deformationernas storlek. Den här uppsatsen belyser några viktiga problem och risker som kan uppstå under tunnelbyggnationen, dessa upptäckter kan därför vara användbara och värdefulla under hela byggnationen.

Les failles dans la croûte supérieure sont des zones de déformation localisées capables de conduire des fluides sur de longues distances. L'estimation de la perméabilité des zones de failles et de leurs propriétés hydromécaniques est cruciale dans nombreux domaines de recherche et applications industrielles. Dans l'industrie pétrolière, et plus particulièrement dans les applications d'exploration et de production, l'intégrité de l'étanchéité des failles doit être évaluée pour la détection des pièges à hydrocarbures. Il existe déjà des approches permettant d'estimer la capacité de scellement latéral d'une faille à partir de la teneur en argile des couches (par exemple le Shale Gouge Ratio). Pourtant, les conditions dans lesquelles la faille se comporte comme un conduit le long de sa structure ne sont pas encore suffisamment contraintes. Dans ce contexte, la géomécanique peut apporter un éclairage complémentaire sur les paramétres qui contrôlent le comportement hydrodynamique de la faille. Ces paramètres comprennent le champ de contraintes, la pression du fluide, l'orientation des structures de la zone de faille et les propriétés des matériaux. Des expériences d'injection à une échelle décamétrique ont été réalisées dans une zone de faille située dans le site expérimental de Tournemire, dans le sud de la France, au cours desquelles la pression et le débit du fluide, la déformation du massif, la sismicité ont été suivis. Sur la base des observations issues de ces expériences, une étude numérique a été réalisée pour explorer l'évolution de la perméabilité etétablir le lien avec la réponse hydromécanique de la faille ainsi que la sismicité induite. Les comportements des failles secondaires, les fractures de la zone endommagée ainsi que la roche encaissante ont été modélisés numériquement en utilisant la méthode des éléments discrets. La modélisation des essais expérimentaux et l'analyse des modèles génériques utilisés pour les études paramétriques ont mis en évidence le rôle majeur des conditions de contrainte in situ. L'effet combiné de la contrainte et de l'orientation des structures de la faille détermine en premier lieu la nature de la réactivation selon le concept de l'état de contrainte critique de la faille décrit dans la littérature. Pour des conditions de contrainte et des éléments structuraux donnés, il a été démontré que selon le niveau de pression du fluide, la faille offre trois gammes différentes de perméabilité : i) perméabilité équivalente à la perméabilité de la formation, ii) 2 à 4 ordres de grandeur plus élevés et iii) plus de 4 ordres de grandeur plus élevés. Alors que pour les deux cas extrêmes, la faille est caractérisée comme étant hydromécaniquement active ou inactive, le second cas est principalement contrôlé par des mécanismes de chenalisation du fluide favorisés par des hétérogénéités aussi bien à l'échelle d'une seule fracture ou qu'à l'échelle du réseau de fractures. Les changements dans les propriétés hydrauliques sont dans certains cas détectés par la sismicité induite lors de l'injection en supposant que la sismicité est l'effet direct de la propagation du fluide, de l'augmentation de la pression du fluide et de la chute de la contrainte effective. Néanmoins, les mécanismes à l'origine de la sismicité induite par injection sont encore peu connus. A partir des résultats expérimentaux du site de Tournemire, le rôle de la diffusivité hydraulique des structures de la faille a été exploré sur la sismicité observée dans le cadre d'une analyse hydro-mécanique. Les résultats indiquent que la microsismicité induite était probablement liée à des perturbations de contrainte résultantes d'une déformation asismique importante plutôt que de la propagation de fluides à travers des structures hydrauliquement connectées. / Faults in the Earth crust are localized zones of deformation which can drive fluids over long distances. Estimating the permeability of fault zones and their hydro-mechanical properties is crucial in a wide range of fields of research and industrial applications. In the petroleum industry, and more specifically in exploration and production applications, the seal integrity of faults in low permeability formations (e.g. shale) needs to be evaluated for the detection of hydrocarbon traps. There already exist approaches able to sufficiently estimate the "side-sealing" capacity of a fault based on the clay or shale content of the layers (e.g. Shale Gouge Ratio). Nevertheless, the conditions under which the fault acts as a drain along its structure are still not properly constrained. In this context, the response of the fault is directly controlled by a number of factors that can be better approached from a geomechanics point of view. These factors include the stress field, the fluid pressure, the orientation of the fault-related structures and the material properties. Meso-scale field injection experiments were carried out inside a fault zone located in the Tournemire massif at the South of France during which the fluid pressure, the deformation, the seismicity and the flow rate were monitored. Based on the Tournemire experiments and field observations, a numerical study was performed exploring the evolution of the permeability and how it is related to the fault hydro-mechanical reactivation and potentially to the induced seismicity. Fault-related structures such as subsidiary faults or fractures that were targeted during the experiments together with the surrounding intact rock, were modeled using the Discrete Element method. Modeling of the experimental tests and the analysis of generic models used to perform parametric studies highlighted the primary role of the in-situ stress conditions. The combined effect of stress and orientation of the fault structures determine in the first place the nature of the reactivation according to the critically stressed fault concept reported in the literature. For given stress conditions and structural features, it was shown that depending on the fluid pressure level, the fault offers three different ranges of permeability: i) permeability that is equivalent to the formation's permeability, ii) 2 to 4 orders of magnitude higher and iii) more than 4 orders of magnitude higher. While for the two extreme cases the fault is characterized as hydro-mechanically inactive or active, the second case is mostly controlled by fluid channeling mechanisms promoted by heterogeneities at the scale of a single fracture or at the scale of the fracture network. Changes in the hydraulic properties are in some cases detected by the seismicity triggered during the injection under the assumption that the seismicity is the direct effect of fluid propagation, fluid pressure increase and effective stress drop.However, the mechanisms behind the injection induced seismicity are still poorly understood. Using experimental results from the Tournemire site, the role of the hydraulic diffusivity of the fault-related structures was explored on the recorded seismicity in the framework of a hydro-mechanical analysis. The results suggest that the induced microseismicity was possibly related to stress perturbations caused by a significant aseismic deformation rather than fluid propagation through hydraulically connected structures.

The objective of this thesis is to compare applications of seismic and geoelectric methods and to state recommendations for their application in future geological prospection, especially application of shallow seismic reflection. Another goal was verification of assumed course of tectonic lines and thickness and character of sedimentary infill, which are important for calculation of seismic hazard by actual standards in context with effort of prolonging licence and also expansion of nuclear power plant Dukovany. When selecting locations for survey there was an effort to confirm the position of the Diendorf-Boskovice zone border and fault zones leading through the zone. The survey was done using multi- electrode electrical resistivity tomography, refraction and reflection seismic.

In the first article, the seismic properties for a suite of rocks along the West Cycladic Detachment System (Greece) are calculated, using Electron backscatter diffraction (EBSD) measurements and the minerals’ elastic stiffness tensors. Muscovite and glaucophane well defined crystallographic preferred orientation increases the seismic anisotropy. Maximum Pwave velocities have the same orientation as the Miocene extension and maximum S-wave anisotropy is subhorizontal, parallel with mineral alignment, suggesting strong radial anisotropy with a slow subvertical axis of symmetry. In the second article, teleseismic receiver functions are calculated for an array of stations in the Cyclades and decomposed into back-azimuth harmonics to visualise the variations in structure and anisotropy across the array. Synthetic receiver functions are modeled using the first order structural observations of seismic discontinuities and EBSD data. They indicate 5% of anisotropy with slow symmetry axis in the upper crust, and demonstrate the importance of rock textural constraints in seismic velocity profile interpretation.

The N.N.W.-S.S.E. striking Rustenburg Fault zone, in the western Transvaal Basin, South Africa, has been mapped, in order to unravel its tectonic history. Thickness differences in the Daspoort Formation of the Pretoria Group on opposite sides of the Fault suggest that the Fault was active during Pretoria Group sedimentation, with normal faulting producing localised second-order basins on the down-thrown side of the Fault. In post-Pretoria Group times, but before the intrusion of the Bushveld Complex at -2050 Ma, the area surrounding the Fault zone underwent two compressive events. The first was directed N.E.S. W., producing S.E.-N.W. trending folds, and the second was directed N.W.-S.E., producing N.E.-S.W. trending folds. The second set of folds refolded the first set to form typical transitional Type 1-Type 2 interference folding, and this compression ultimately caused reactivation of the Rustenburg Fault, so that dextral strike-slip movement displaced the Pretoria Group sediments by up to 10.6 km. The subsequent intrusion of the Bushveld Complex into the adjacent strata intensely recrystallised, and often assimilated, the strata along the Fault zone. The fault rocks within the Fault zone were also recrystallised, destroying any pre-existing tectonic fabric. Locally, the Fault zone has been assimilated by the Bushveld Complex. After the intrusion of the Bushveld Complex, little movement has occurred along the Fault, especially where the Fault passes under areas occupied by the Bushveld Complex. It is thought that the crystallisation of the Bushveld Complex has rheologically strengthened the neighbouring strata, preventing them from being refaulted. This model presented above is at variance with previous assumptions that continuous regional extension during Pretoria Group sedimentation culminated in the intrusion of the Bushveld Complex. / Dissertation (MSc)--University of Pretoria, 1997. / gm2015 / Mining Engineering / MSc / Unrestricted

The presence of active fault traces in proximity to any new infrastructure project is a major concern for the design process. The relative displacements that can be experienced in surface fault rupture during a seismic event must be either entirely avoided or mitigated in some way. Blind faults present a significant challenge to engineers attempting to identify these hazards. Current standards of practice employed to locate these features are time consuming and costly. This work investigates the geophysical methods of refraction microtremor (ReMi) and seismic refraction with regard to their applicability in this task. By imaging a distinct lateral variation in the shear wave velocity (Vs) profile across a short horizontal distance, these methods may provide a means of constraining traditional investigation techniques to a more focused area. The ReMi method is still very new, but holds key advantages over other geophysical methods in its ease of application and ability to achieve good results in highly urban settings. It is one of the few geophysical techniques that does not suffer in the presence of high amplitude ambient vibrations. The seismic refraction method is here applied in an attempt to corroborate data obtained through the ReMi analysis procedure. Sensitivity, precision parametric studies are carried out in order to learn how to best apply the ReMi method. Both tests are then applied at a previously trenched fault trace to determine whether the data can be matched to the subsurface information. Finally, the methods are deployed at a location with an inferred fault trace where little to nothing is known about the subsurface. The precision study indicates a coefficient of variation for the ReMi method on the order of 7%. At the known fault trace both methods generally agree qualitatively with available subsurface data and each other. Using the ReMi method, a marked shift is observed in the Vs profile laterally across the fault trace. In the case of the inferred fault trace, the same type of lateral variation in the V­­s profile is observed using the ReMi method. The seismic refraction at this site does not agree with the ReMi data, but seems reasonable given the visible geomorphology. Receiver arrays placed in close proximity to the inferred fault trace recorded erratic signals during seismic refraction testing, and displayed abnormal response modes after transforming the ReMi data to frequency-slowness space. These anomalies may possibly be attributed to the presence of abnormal subsurface structural geometry indicative of faulting.

No description available.

Over the past century, a series of large (> 6.5) magnitude earthquakes have struck along the North Anatolian Fault Zone (NAFZ) in Turkey in a roughly East to West progression. The progression of this earthquake sequence began in 1939 with the Ms 8.0 earthquake near the town of Erzincan and continued westward, with two of the most recent ruptures occurring near the Sea of Marmara in 1999. The sequential nature of ruptures along this fault zone implies that there is a connection between the location of the previous rupture and that of the future rupture zones. This study focuses on understanding how previous rupture events and tectonic influences affect the stress regime of the NAFZ and how these stress changes affect the probability of future rupture along any unbroken segments of the fault zone using a two dimensional finite element modeling program. In this study, stress changes due to an earthquake are estimated using the slip history of the event, estimations of rock and fault properties along the fault zone (elastic parameters), and the far-field tectonic influence due to plate motions. Stress changes are not measured directly. The stress regime is then used to calculate the probability of rupture along another segment of the fault zone. This study found that when improper estimates of rock properties are utilized, the stress changes may be under- or over- estimated by as much as 350% or more. Because these calculated stress changes are used in probability calculations, the estimates of probability can be off by as much as 20%. A two dimensional model was built to reflect the interpreted geophysical and geological variations in elastic parameters and the 1939 through 1999 rupture sequence was modeled. The far-field tectonic influence due to plate motions contributed between 1 and 4 bars of stress to the unbroken segments of the fault zone while earthquake events transferred up to 50 bars of stress to the adjacent portions of the fault zone. The 1999 rupture events near Izmit and Düzce have increased the probability of rupture during the next ten years along faults in the Marmara Sea to 38% while decreasing the probability of rupture along the faults near the city of Bursa by ~6%. Large amounts of strain accumulation are interpreted along faults in the Marmara Sea, further compounding the case for a large rupture event occurring in that area in the future. / Ph. D.