Le département de la Vendée est classé en zone de risque sismique niveau 3, en raison d’une activité sismique continue et d’une sismicité historique de forte intensité avec l’évènement majeur du 25 janvier 1799 (M6) dans le Marais Breton. Ce séisme a provoqué des dégâts massifs localement à Bouin et dans la région nantaise, et a été largement ressenti dans l’Ouest de la France. La Vendée littorale est située sur la côte atlantique française au sud du cisaillement sud-armoricain. Elle est caractérisée par de nombreuses structures héritées d’origine varisque et d’orientation NW-SE, réactivées au Mésozoïque et au Cénozoïque délimitant des marais côtiers holocènes. L’enjeu de cette thèse est de caractériser la géométrie des éventuelles failles plio-quaternaires et potentiellement actives dans cette région, en s’intéressant particulièrement à la faille de Machecoul, bordière des bassins sédimentaires du Marais Breton et de la Baie de Bourgneuf et candidate potentielle pour le séisme Vendéen de 1799. Notre approche est pluridisciplinaire terre-mer, intégrant sismologie (réseau temporaire), géophysique marine (sismique réflexion Chirp et Sparker, bathymétrie haute résolution), morpho-tectonique, gravimétrie, étude de forages et sismicité historique. Notre étude a permis d’analyser et de caractériser (1) la structure et la géométrie en profondeur du système de failles normales de Machecoul, (2) la localisation des dépocentres plioquaternaires du Marais Breton et de la Baie de Bourgneuf en relation avec le système de failles de Machecoul, atteignant localement une vingtaine de mètres d’épaisseur, (3) la perturbation du réseau hydrographique et l’incision récente du relief du compartiment inférieur de la faille de Machecoul, probablement d’âge pliocène, ainsi que (4) l’activité microsismique de la faille de Machecoul. Nos données suggèrent que la sédimentation plioquaternaire des bassins en mer comme à terre au sud de la faille de Machecoul a pu être contrôlée par cette faille probablement héritée de l’Eocène. Ce travail confirme l’intérêt multi-disciplinaire de l’étude des failles en domaine de déformation faible et apporte un faisceau d’indices permettant de relier la faille de Machecoul à la rupture du séisme Vendéen de 1799 (M6), évènement historique de référence dans l’Ouest de la France de par son ampleur, et par là même de ses conséquences dans une zone littorale de plus en plus peuplée. / The Vendée department is classified as a level 3 seismic risk zone because of a moderate background seismic activity and a strong historical seismicity dominated by the 1799 January 25th (M6) major event in the MaraisBreton. This earthquake caused local massive damages in Bouin and around Nantes, and its perception area stretched widely in the West of France. Coastal Vendée is located on the French Atlantic coast, south of the SouthArmorican Shear Zone. This area is made of numerous NW-SE trending hercynian inherited structures, reactivated during Mesozoic and Cenozoic times and delimiting holocene coastal marschlands. The main goal of this thesis is to characterize the geometry of potential plio-quaternary active faults in the area by focusing on the Machecoul fault, bounding the Marais Breton and the Baie de Bourgneuf sedimentary basins and potential candidate for the 1799 earthquake. We used a multidisciplinary onshore-offshore approach, including seismology (temporary network), marine geophysics (Chirp and Sparker seismic reflexion, high resolution bathymetry), morphotectonic, gravity, onshore drilling database and historical seismicity.Our results allowed us to analyze and characterize (1) the Machecoul normal faults system structure and geometry in depth, (2) the plio-quaternary depocenters location in Marais Breton and Baie de Bourgneuf in relation with the Machecoul fault system, reaching locally around twenty meters thick, (3) the hydrographic network perturbation and recent incision of the Machecoul fault footwall, probably pliocene aged relief, (4) the microseismic activity of the Machecoul fault. Our data suggest that the plioquaternary sedimentation of the marine and terrestrial basins located in the south of the fault could be controlled by this inherited fault, probably dated from Eocene age.This work confirms the importance of multi-disciplinary approach in the study of faults in low deformation context and provides a body of evidence allowing to connect the Machecoul fault to the rupture of the 1799 Vendée earthquake (M6), historic and reference event in the western part of France given its scale and so its consequences in the more and more densely populated coastal area.

Modern mines require systems that quickly deliver backfill to support the rock mass surrounding underground openings. Cemented Paste Backfill (CPB) is one such backfilling method, but concerns have been raised about CPB’s liquefaction susceptibility especially when the material has just been placed, and if it is exposed to earthquakes or large mining induced seismic events. Conventional geotechnical earthquake engineering for surface structures is now relatively advanced and well accepted, and so the objective of this thesis is to consider how that framework might be extended to assess the liquefaction potential of CPB. Seismic records were analyzed for earthquakes and for large mining induced events. Important seismological trends were consistent for rockbursts and earthquakes when the signals were recorded at distances as proximate as one kilometre, suggesting that the conventional earthquake engineering approach might plausibly be adapted for such design situations. For production blasts and for more proximate locations to rockbursts, much higher frequencies dominate and therefore new design methods may be required. Monotonic triaxial tests conducted on normally consolidated uncemented mine tailings demonstrated that the material is initially contractive up to a phase transition point, beyond which dilation occurs. Most importantly the material never exhibits unstable strain softening behaviour in compression, and only temporary or limited liquefaction in extension. The addition of 3% binder results in initial sample void ratios that are even higher than their uncemented counterparts, and yet the material friction is slightly enhanced when tested at 4 hours cure. These results suggest that the flow liquefaction phenomenon commonly associate with undrained loose sand fills will not occur with paste backfill. Cyclic triaxial test results analyzed in terms of number of cycles to failure for a given cyclic stress ratio exhibited a trend consistent with previous tests on similar materials. However, the addition of 3% binder and testing at 4 hours cure resulted in an order of magnitude larger number of cycles to failure – a surprising and dramatic increase, suggesting good resistance of the material to cyclic mobility. Future research is recommended to build on these results and develop more robust methods for liquefaction assessment of CPB.

Modern mines require systems that quickly deliver backfill to support the rock mass surrounding underground openings. Cemented Paste Backfill (CPB) is one such backfilling method, but concerns have been raised about CPB’s liquefaction susceptibility especially when the material has just been placed, and if it is exposed to earthquakes or large mining induced seismic events. Conventional geotechnical earthquake engineering for surface structures is now relatively advanced and well accepted, and so the objective of this thesis is to consider how that framework might be extended to assess the liquefaction potential of CPB. Seismic records were analyzed for earthquakes and for large mining induced events. Important seismological trends were consistent for rockbursts and earthquakes when the signals were recorded at distances as proximate as one kilometre, suggesting that the conventional earthquake engineering approach might plausibly be adapted for such design situations. For production blasts and for more proximate locations to rockbursts, much higher frequencies dominate and therefore new design methods may be required. Monotonic triaxial tests conducted on normally consolidated uncemented mine tailings demonstrated that the material is initially contractive up to a phase transition point, beyond which dilation occurs. Most importantly the material never exhibits unstable strain softening behaviour in compression, and only temporary or limited liquefaction in extension. The addition of 3% binder results in initial sample void ratios that are even higher than their uncemented counterparts, and yet the material friction is slightly enhanced when tested at 4 hours cure. These results suggest that the flow liquefaction phenomenon commonly associate with undrained loose sand fills will not occur with paste backfill. Cyclic triaxial test results analyzed in terms of number of cycles to failure for a given cyclic stress ratio exhibited a trend consistent with previous tests on similar materials. However, the addition of 3% binder and testing at 4 hours cure resulted in an order of magnitude larger number of cycles to failure – a surprising and dramatic increase, suggesting good resistance of the material to cyclic mobility. Future research is recommended to build on these results and develop more robust methods for liquefaction assessment of CPB.

No description available.

Induced seismicity is a common phenomenon that occurs as soon as the stress state in the subsurface is externally altered in a way that faults are destabilized. It is especially problematic in stable tectonic regions where the area is not used to earthquakes; the infrastructure is not built to withstand ground movement and thus when the induced seismicity occurs damage can follow. In this thesis, mining-induced seismicity has been studied at the Dannemora mine, located in central Sweden, with the aim to locate the seismicity and gain understanding of its occurrence and behavior. The mining company, Dannemora Mineral AB, provided with blasting locations and times, as well as maps over the mine's orebodies and stopes. Seismic data acquired between 01 July 2014 - 25 March 2015 from 4 temporary seismic stations, deployed in the summer of 2014 surrounding the mine, along with 8 SNSN stations was analyzed. The project encompassed field work and processing of the data, which involved different methods to investigate the characteristics of the mine's seismicity: Statistics were kept to record the activity rate of the seismicity over time; spectral analysis was used to study the frequency content of the seismicity; particle motion plots were constructed to identify body-phases in the seismicity; Local Earthquake Tomography was used to upgrade the velocity model of the mine and to relocate the induced seismicity with more accuracy; cross-correlation was used to find events originating from similar sources; and finally, magnitude analysis was used to compare the different types of seismicity within the mine. Three main types of induced events were observed in the mine: low-frequency events with clear first arrivals, emergent events with long duration, and high-frequency events that could either have clear first arrivals or emergent-like with long durations. Through the analysis of their characteristics, they were linked to different types of rockbursts. The low-frequency events were linked to both reactivation of fault zones triggered by the mine activity, and rockbursts within the mine directly related to the mining. The emergent and high-frequency events were also linked to rockbursts directly related to the mine activity, e.g. ejection of rock from the tunnel walls or arch collapses in stopes.

Geomorphic, structural and chronological data are used to establish the late Quaternary paleoseismicity of the active dextral-oblique Northern Esk Fault in North Canterbury, New Zealand. Detailed field mapping of the preserved c. 35 km of surface traces between the Hurunui River and Ashley Head reveals variations in strike ranging from 005° to 057°. Along with kinematic data collected from fault plane striae and offset geomorphic markers along the length of the fault these variations are used to distinguish six structural subsections of the main trace, four dextral-reverse and two dextral-normal. Displacements of geomorphic markers such as minor streams and ridges are measured using differential GPS and rangefinder equipment to reveal lateral offsets ranging from 3.4 to 23.7 m and vertical offsets ranging from < 1 to 13.5 m. Characteristic single event displacements of c. 5 m and c. 2 m have been calculated for strike-slip and reverse sections respectively. The use of fault scaling relationships reveals an anomalously high displacement to surface rupture length ratio when compared to global data sets. Fault scaling relationships based on width limited ruptures and magnitude probabilities from point measurements of displacement imply earthquake magnitudes of Mw 7.0 to 7.5. Optically Stimulated Luminescence (OSL) ages from displaced Holocene alluvial terraces at the northern extent of the active trace along with OSL and radiocarbon samples of the central sections constrain the timing of the last two surface rupturing events (11.15 ±1.65 and 3.5 ± 2.8 ka) and suggest a recurrence interval of c. 5612 ± 445 years and late Quaternary reverse and dextral slip rates of c. 0.31 mm/yr and 0.82 mm/yr respectively. The results of this study show that the Northern Esk Fault accommodates an important component of the c. 0.7 – 2 mm/yr of unresolved strain across the plate boundary within the North Canterbury region and affirm the Esk Fault as a source of potentially damaging ground shaking in the Canterbury region.

Study area, the Eskipazar Basin, is located in the western part of the North Anatolian Fault System. It is a 3-5 km wide, 10 km long and NWSE trending depression, bounded by a complex array of oblique-slip normal faults and strike-slip faults. The Eskipazar Basin is interpreted to be a superimposed basin. The basin fill is composed of two different units deposited under the control of different tectonic regimes, namely the paleotectonic and the neotectonic regimes. The latest paleotectonic fill of the basin is the fluvio-lacustrine deposits of the paleotectonic Eskipazar formation. This formation is unconformably overlain by a group of neotectonic units namely, the Budaklar, the Karkin and the imanlar formations. The unconformity in between these paleotectonic and neotectonic units represents the time interval during which the paleotectonic period comes to end and the neotectonic period started. Thus, onset age of the strike-slip neotectonic regime in the study area is Late Pliocene (&amp / #8764 / 2.6 My). Common basin margin-bounding faults of the Eskipazar Basin are the Kadilar fault set, the Beytarla Fault Zone, the Budaklar fault set, the Arslanlar fault set, the Dibek fault, the Karkin fault, the Boztepe fault and the Acisu fault. These faults display well preserved fault scarps, in places. Morphological expressions of these faults and their geometrical relationships to regional stress system indicate that these faults are mostlystrike-slip faults with normal component. However the Kadilar fault set displays a different characteristic, being the major fault controlling the basin to the west and it is indeed an oblique slip normal fault. Long term seismicity and their epicentral distribution in and very close to the study area suggest that the Eskipazar basin is located in an area of seismic quiescence, nevertheless the morphotectonic expressions of the faults exposing in the basin suggest that these faults are active. Since the most of settlements are located on different lithologies of poorly consolidated deposits of the Eskipazar formation susceptible to landslides, the area is open to future earthquake hazard. Therefore, structures and settlements have to be constructed on strong ground away from active faults.

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 (Habilitationsschrift)--Ruhr-Universität Bochum, 2005. / "February 2006"--P. [2] of cover. Includes bibliographical references. Also available via the World Wide Web.

Η παρούσα διδακτορική διατριβή χωρίζεται σε έξι κεφάλαια: Στο πρώτο κεφάλαιο μελετάται η γεωλογία, τεκτονική και η σεισμική δραστηριότητα στην ευρύτερη περιοχή μελέτης. Συγκεντρώνονται όλα τα διαθέσιμα στοιχεία από προηγούμενες μελέτες και δίνεται ιδιαίτερη έμφαση στα γεωλογικά, τεκτονικά και γεωτεχνικά χαρακτηριστικά της υπό εξέτασης περιοχής. Στο δεύτερο κεφάλαιο διερευνώνται οι επιπτώσεις που θα έχει στους επιφανειακούς σχηματισμούς η δραστηριοποίηση ρηγμάτων με ή χωρίς σεισμούς στην περιοχή της διώρυγας της Κορίνθου. Οι προσομοιώσεις διάδοσης της σεισμικής διάρρηξης για κάθε μία περίπτωση πραγματοποιήθηκε με τη μέθοδο των πεπερασμένων στοιχείων, με στόχο να αποκτηθεί μία πιο σαφής εικόνα της κατανομής των παραμορφώσεων, που αναμένεται να αναπτυχθούν σαν αποτέλεσμα της διάρρηξης των συγκεκριμένων ρηγμάτων, και να προσδιοριστούν περιοχές με αναμενόμενες μέγιστες παραμορφώσεις. Στο τρίτο κεφάλαιο προσδιορίστηκαν οι πιο σημαντικές και καλά προσδιορισμένες γραμμικές σεισμικές πηγές (ενεργά ρήγματα) που είναι πιθανόν να επηρεάσουν την περιοχή της διώρυγας και υπολογίσθηκε η σεισμική επικινδυνότητα. Προσδιορίστηκαν οι μέγιστες αναμενόμενες τιμές της εδαφικής επιτάχυνσης, ταχύτητας και μετατόπισης καθώς και της έντασης Arias μια παραμέτρου που παρουσιάζει καλή συσχέτιση με σεισμικά προκαλούμενες κατολισθήσεις, για διάφορες χρονικές περιόδους. Στο τέταρτο κεφάλαιο, με τη μέθοδο των συνοριακών στοιχείων μελετάται η επίδραση που θα έχει στα πρανή της διώρυγας η πιθανή ενεργοποίηση τριών διαφορετικών σεισμικών πηγών οι οποίες εντοπίζονται στην ευρύτερη περιοχή, με βασικό στόχο τον προσδιορισμό πιθανών θέσεων εκδήλωσης αστοχιών και κατ' επέκταση τον προσδιορισμό της πιο δυνητικά επικίνδυνης σεισμικής πηγής. Στο πέμπτο κεφάλαιο περιγράφεται η κατασκευή μιας ράβδου ακουστικής εκπομπής που προτείνεται για την συνεχή παρακολούθηση τμημάτων των πρανών της διώρυγας με αυξημένο πρόβλημα πιθανών καταπτώσεων. Παρουσιάζονται τα αποτελέσματα της επεξεργασίας και ανάλυσης ακουστικών εκπομπών από τις εργαστηριακές δοκιμές της ράβδου και προτείνεται ένα πλήρες σύστημα παρακολούθησης όσον αφορά την παρακολούθηση κατολισθητικών φαινομένων στη Διώρυγα της Κορίνθου. Στο τελευταίο κεφάλαιο παρατίθενται τα συμπεράσματα της παρούσας διδακτορικής διατριβής, προσδιορίζονται συγκεκριμένες θέσεις στη Διώρυγα της Κορίνθου με αυξημένο πρόβλημα εμφάνισης κατολισθητικών φαινομένων, προτείνονται λύσεις αντιμετώπισης του προβλήματος. Τέλος γίνονται προτάσεις για το πως πρέπει να συνεχιστεί η έρευνα και η αξιοποίηση των αποτελεσμάτων. / -