Sur les dernières décennies, progresse sur la compréhension de la sismicité de clustering dans le temps, taille et l'espace ont été chassés par deux approches parallèles. De l'on étudie la main sur la mécanique des failles dans un milieu élastique soutiennent pour la contrainte statique de déclenchement à dominent dans le champ proche, c'est à dire à une distance de moins de 10 longueur de faute. De l'autre part, les propriétés de champ moyen du déclenchement sont reproduits en utilisant des effets en cascade dans modèles de processus point. Dans cette étude, nous essayons de concilier ces approches en soulignant l'importance de la faille de style sur les propriétés moyennes de la sismicité. En commençant par l'étude du taux de sismicité déclenchée par la Ville Muzaffarabad, au Cachemire, 2005 Mw = 7.6, Ms = 7,7 tremblement de terre, qui apparaît comme supérieure à la moyenne dans l'analyse des séquences répliques dans la ceinture de collision Inde-Asie, nous décidons de la productivité évènement grève de glissement sont en moyenne 4 fois plus petit que la poussée des failles de productivité. En utilisant le catalogue sismique global, nous étendre ce résultat comme tous les paramètres de la loi d'Omori (P, K, α, N (t)) étant dépendant failles styles. Dans le K ETAS modèle solide, N et de faibles valeurs de α sont entraînés par branchement ratio élevé (n). Comme conséquences de la relative n haute - La valeur la poussée des événements, il prédit aussi une faible p - La valeur pour l'événement de la poussée que comparer à bordereau de grève et des manifestations normales de la PN> PS S> PT que nous observons. Dans l'état de taux et cadre de la friction cela implique un changement dans les habitudes hétérogénéité stress. Nous ne résolvent pas tout changement dans le taux robustes foreshocks, p ' - La valeur, alors que notre analyse nous permettra d'étendre B ˚ droit aths dans le temps, d'espace et mécanisme focal. Pour des failles inverses, l'ampleur différence et la distance entre le choc principal de la plus grande réplique sont un peu moins que pour les défauts de glissement de grève. La distribution des intervalles de temps entre mainshocks et leurs le plus grand répliques est conforme au droit d'Omori, mais avec un taux un peu plus rapide de la carie que pour les répliques en général. Ceci implique que la plus grande réplique est plus susceptible de survient plus tôt que plus tard dans une séquence donnée de répliques. Par ailleurs, cette constatation plaide en faveur allant au-delà du modèle de point de branchement, avec des implications pour les prévisions à court terme. Aussi nous résoudre la dépendance univoque de p - La valeur du droit à l'ampleur Omori choc principal pour la réplique dans les 10 jours après la survenance choc principal, cette dépendance étant perdus lors de l'utilisation des séquences en cascade complète. Nous trouvons ce seuil correspond également le temps à un changement dans les schémas de diffusion, tous ces changements se synchroniser avec l'apparition de la plus grande réplique. En conséquence, nos résultats convergent vers le rôle clé du secondaire répliques sur la mécanique de la taille, le temps et l'espace modèle de processus en cascade. / On the last decades, progresses on the understanding of clustering seismicity in time, size and space have been driven by two parallel approaches. From the one hand studies on the mechanics of faulting in an elastic medium argue for the static stress triggering to dominate in the near field, i.e within distance less than 10 fault length. From the other hand, mean field properties of the triggering are reproduced using cascading effects in point process models. In this study we try to reconcile these approaches by emphasizing the importance of faulting style on average properties of seismicity. Starting with the study of the seismicity rate triggered by the Muzaffarabad, Kashmir, 2005 Mw = 7.6, Ms = 7.7 earthquake, which appears as above the average when analysing the aftershocks sequences in the India-Asia collision belt, we resolve the strike slip event productivity to be on average 4 times smaller than the thrust faulting productivity. Using global earthquake catalog, we further extend this result as all the parameters of the Omori law (p, K, α, N (t)) being dependent on faulting styles. Within the ETAS model strong K, N and low α values are driven by high branching ratio (n). As consequences of the relative high n − value of the thrust events, it also predicts a lower p − value for thrust event as compare to strike slip and normal events as the pN > pS S > pT we observe. Within rate and state friction framework it implies a change in stress heterogeneity patterns. We do not resolve any robust changes in foreshocks rate, p′ − value, whereas our analysis allow us to extend B˚aths law in time, space and focal mechanism. For reverse faults, both the magnitude difference and the distance from the mainshock to the largest aftershock are somewhat less than for strike slip faults. The distribution of time intervals between mainshocks and their largest aftershocks is consistent with Omori's law but with a somewhat faster rate of decay than for aftershocks in general. This implies that the largest aftershock is more likely to occurs earlier than later in a given sequence of aftershocks. Moreover, this finding argues for going beyond the branching point model, with implications for short term forecasts. Also we resolve unambiguous dependency of p − value of Omori law to mainshock magnitude for the aftershock within 10 days after the mainshock occurrence, this dependency being lost when using complete cascade sequences. We find this time threshold also corresponds to a change in diffusion patterns, all these changes synchronize with the occurrence of the largest aftershock. Accordingly, our results converge toward the key role of the secondary aftershocks on the mechanics of size, time and space pattern of cascading processes.

I use temporal lidar and radar to reveal fault rupture kinematics and to test a method of mapping earthquake-induced structural damage. Using pre- and post-event data, these applications of remote technology offer unique perspectives of earthquake effects. Lidar point clouds can produce high resolution, three-dimensional terrain maps, so subtle landscape shifts can be discerned through temporal analysis, providing detailed imagery of co-seismic ground displacement and faulting. All-weather radar systems record back-scattered signal amplitude and phase. Pre- and post-event comparisons of phase can illuminate co-seismic structural damage using an oblique look angle, most sensitive to changes in building heights. Extracted information from these geodetic methods may be used to inform decisions on future earthquake modeling and emergency response. In the first major section of this thesis, I calculate co-seismic 3D ground deformation produced by the Papatea fault using differential lidar. I demonstrate that this fault - a key element within the 2016 Mw 7.8 Kaikoura earthquake - has a distinctly non-planar geometry, far exceeded typical co-seismic slip-to-length ratios, and defied Andersonian mechanics by slipping vertically at steep angles. Its surface deformation is poorly reproduced by elastic dislocation models, suggesting the Papatea fault did not release stored strain energy as typically assumed, perhaps explaining its seismic quiescence in back-projections. Instead, it slipped in response to neighboring fault movements, creating a localized space problem, accounting for its anelastic deformation field. Thus, modeling complex, multiple-fault earthquakes as slip on planar faults embedded in an elastic medium may not always be appropriate. For the second major part of this thesis, I compare mean values of interferometric synthetic aperture radar (InSAR) coherence change across four case studies of earthquake-induced building damage. These include the 2016 Amatrice earthquake, the 2017 Puebla-Morelos earthquake, the 2017 Sarpol-e-Zahab earthquake, and the 2018 Anchorage earthquake. I examine the influences of environmental and urban characteristics on co-seismic coherence change using Sentinel-1 imagery and compare the outcomes of various damage levels. I do not find consistent values of mean coherence change to distinguish levels of damage across the case studies, indicating coherence change values vary with location, environment, and damage pattern. However, this method of damage mapping shows potential as a useful tool in earthquake emergency response, capable of quickly identifying localized areas of high damage in areas with low snow and vegetation cover. Given the large spatial coverage and relatively quick, low-cost acquisition of SAR imagery, this method could provide damage estimates for unsafe or remote regions or for areas unable to self-report damage. / Graduate

Many seismic hazard source parameters such as slip rate, total displacement, strain accommodation, geographic fault location, etc. are poorly constrained in the New Madrid seismic zone (NMSZ). This is in large part due to the masking effect of the thick Mississippi embayment sediment package on seismogenic structures and features. Consequently, much of the subsurface geologic characterization needed for understanding seismic hazard sources requires geophysical imaging. Recent seismic reflection surveys 12 km NE of the Reelfoot Fault stepover arm of the NMSZ have suggested a northeast-oriented transpressional fault zone extending across the Reelfoot Fault stepover arm where its dextral displacement at seismogenic depth is unbalanced with the surface expression, the Reelfoot Scarp. New high-resolution seismic reflection surveys were acquired across the southwestern back projection of the hypothesized structure at a potential piercing point with the Reelfoot Fault near Proctor City, TN. The resultant images show steeply dipping northeast striking faults with uplifted and arched post-Paleozoic reflectors that extend into the Quaternary sediments, consistent with the findings of the previous surveys. The new imaged faults form a ~500-meter-wide positive flower structure, with vertical displacements of 16 m and 50 m at the top of the Eocene and top of the Paleozoic reflectors, respectively. Results corroborate the Axial Fault extending to the northeast, and provide geological evidence for Reelfoot Fault segmentation. Furthermore, the near-surface SH-wave seismic profiles show the through-going shear deformation has continued into the Quaternary, thus indicating seismogenic strain has not been completely transferred to the Reelfoot Fault, providing additional evidence for accommodating the strain imbalance.

No description available.

Deformation in continents is not restricted to narrow bands but is spread over great distances within their interiors. A number of lines of evidence, including the distribution of earthquakes, reveal that the strength of different continental regions varies markedly. While it is relatively easy to qualitatively map out these variations, little progress has been made in quantifying the range of strength in the continents and identifying the physical mechanisms that control these variations. I investigate crustal deformation associated with the earthquake cycle, inflation of magma chambers beneath volcanoes, and changes in surface loads. Results of these models has important implications for our understanding of large-scale continental deformation and mountain building, in addition to both seismic and volcanic hazard assessment. Novel analytic solutions for simple shear with depth-dependent linear and non-linear viscoelastic rheologies are derived, in addition to analytical solutions for imposed harmonic tractions and displacements on an elastic layer over a Maxwell viscoelastic half space.

Field studies in the southwest Salton Trough between Yaqui Ridge and Borrego Mountain show that the West Salton detachment fault was active during the Pliocene and may have initiated during the latest Miocene. At Yaqui Ridge dominantly east-directed extension is recorded by slickenlines on the NW-striking detachment fault, and shows that the fault is actually a low-angle dextral oblique strike-slip fault. Crustal inheritance is responsible for the position of the fault at Yaqui Ridge, which reactivates a late Cretaceous reverse -sense mylonite zone at map scale. Late Miocene to Pliocene basin fill deposits at Borrego Mountain display progressive unconformities, contain detritus shed from the footwall and damage zone of the West Salton detachment fault, record the growth of a large hanging wall anticline, and document the initiation and evolution of the West Salton detachment fault. The Borrego Mountain anticline is a major hanging wall growth fold that trends - N60 °W and has at least 420 m of structural relief. The late Quaternary Sunset conglomerate is - 600 m thick, lies in angular unconformity on Pliocene basin fill, is bound on the SW by the dextral oblique Sunset fault, and coarsens upward and SW toward the fault. It is dominated by plutonic lithologies from nearby areas, contains up to 10% recycled sandstone clasts from Pliocene deposits, and was shed from the SW side of the then-active Sunset fault. Based on lithologic, stratigraphic, compositional similarities, we correlate this conglomerate to part of the - 1. I - 0.6 Ma Ocotillo Formation. The West Salton detachment fault was folded and deactivated at Yaqui Ridge by the dextral oblique San Felipe fault zone starting - 1. l - 1.3 Ma. The Sunset fault is in the middle of a complex left stepover between the San Felipe fault to the NW and the Fish Creek Mountains fault to the SE. Structural analyses and mapping show that syntec tonic conglomerate, the West Salton detachment fault, and footwall crystalline rocks all have similar fold geometries and record similar amounts of NE-SW shortening. The dominant SE-trending population of slip vectors on the Sunset fault is not present on the West Salton detachment fault and suggests limited or no activation of the older detachment fault by the younger fault zone.

The research area is located to the northern tip of Tuzgolu fault zone in the junction of neotectonic structures, namely, EskiSehir-Cihanbeyli, Sungurlu-Kirikkale and Tuzg&ouml / l&uuml / fault zones (Central Anatolia). The study is carried out in Paleocene sequences of PaSadag group on the structural analysis of bed, gash vein, fault and fault plane slippage data. The method of study based on i) the rose and stereo analysis of the planar structure (beds, gash veins and faults) on ROCKWORKS 2009 software and ii) on fault slip analysis on ANGELIER 1979 software. The bed analyses done on 605 measurements manifest N10&deg / -20&deg / E bedding attitude. The analysis done on 64 gash veins shows a general trend of NNE-SSW (N15&deg / E). The final analysis done on 160 fault planes pointed out a general trend of NNWSSE (N20&deg / W). Analysis based on the fault plane slip data manifest two stages of faulting under almost NE-SW compression during post-Paleocene &ndash / pre-Miocene period and one stage of faulting under WNW-ESE extension most probably during post-Miocene. To conclude, the Paleocene sequences are deformed continuously under WNW-ESE directed compression which is followed by a NE-SW to N-S compression resulted in the development of a reverse to dextral strike slip faulting during post-Paleocene &ndash / pre-Miocene period.

The formation and evolution of metamorphic core complexes has been widely studied using low temperature thermochronometry methods. Interpretation of these data has historically occurred through the lens of the traditional slip rate method which provides a singular rate that unroofing occurs at temporally as well as spatially, and assumes unroofing is dominated by motion on a single master detachment fault. Recently, several new studies have utilized (U-Th)/He ages with a higher spatial density and greater nominal precision to suggest a late-stage rapid increase in the rate of unroofing. This analysis is based on the traditional slip rate method interpretation of broad regions of core complexes that display little to no change in age along the slip direction. An alternative interpretation is presented that instead of a change in slip rate, there may have been a change in the style of unroofing, specifically caused by the transfer of displacement from low-angle detachment faulting to high-angle normal faults. Apatite fission-track (AFT), and apatite and zircon (U-Th)/He (AHe and ZHe) analyses were applied to samples from the Santa Catalina-Rincon (n=8 AHe, and n=9 ZHe) and Harcuvar (n=12 AFT, n=16 AHe, and n=17 ZHe) metamorphic core complexes in an attempt to resolve the possible thermal effects of high-angle normal faulting on core complex formation. Samples from the Harcuvars were taken along a transect parallel to slip direction with some samples specifically targeting high-angle normal fault locations. The AFT data collected here has the advantage of improved analysis and modeling techniques. Also, more than an order of magnitude more data were collected and analyzed than any previous studies within the Harcuvars. The AFT ages include a trend from ~22 Ma in the southwest to ~14 Ma in the northeast and provide a traditional slip rate of 7.1 mm/yr, similar to previous work. However, two major high-angle, detachment-parallel normal faults were identified, and hanging-wall samples are ~3 m.y. older than the footwalls, indicating high-angle normal faults rearranged the surface expression of the distribution of thermochronometer ages to some extent. AHe ages range from 8.1 Ma to 18.4 Ma but in general decrease with increasing distance in the slip direction. ZHe ages generally range between 13.6 Ma and 17.4 Ma. A series of unexpectedly young AFT ages (10-11 Ma), given by three complete samples and distinct population modes in others, suggest that some parts of the range underwent a later-stage unroofing event possibly caused by high-angle faulting. Confined fission-track length distributions were measured for Harcuvar samples and modeled using the modeling software HeFTy to infer thermal histories and calculate local cooling rates. These imply a component of steady cooling in some parts of the range, evidence of a different departure from a single-detachment dominated model. / text

xvi, 121 p. : ill. (some col.), maps (some col.) Also includes two large-scale maps in two separate pdf files. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Deformation across plate boundaries often occurs over broad zones with relative motions between plates typically accommodated by faults of different styles acting together in a complex system. Collision of the Yakutat microplate within the Alaskan portion of the Pacific-North America plate boundary drives deformation over 600 km away where the Denali fault divides predominantly rigid crustal block motions of southern Alaska from distributed deformation in central Alaska. Quaternary geologic mapping along the Nenana River valley and the Japan Hills of the northern foothills of the Alaska Range defines zones of Quaternary thrust faulting recorded in the progressive deformation of Pleistocene fluvial terraces. I use topographic profiles of these terraces and paleoseismic trenching of fault scarps to characterize the Quaternary activity and constrain the subsurface geometry of these faults. Radiocarbon and cosmogenic exposure dating methods provide age control on the stratigraphy in the trenches and landforms offset by these faults. These observations define a 1-1.5 mm/yr slip rate for the Gold King fault which changes laterally from a north-vergent thrust into a north and south vergent thrust wedge that uplifts the Japan Hills. Along the Nenana River valley, the progressive deformation of Pleistocene surfaces defines a north-vergent critically-tapered thrust wedge. The geometry of progressive uplift and folding requires a near planar, south-dipping basal thrust fault with two major north-dipping backthrusts. All three faults were active simultaneously on a scale of 10 4 yrs with slip rates of 0.25-1 mm/yr, until the late Pleistocene when we infer the retreat of glacial ice from the main axis of the Alaska Range caused a change in thrust wedge dynamics. I use the orientation of Quaternary deformation north of the Denali fault to show that strain is highly partitioned and establish geologic constraints on the regional horizontal stress orientation. North of the Denali fault, fault-normal principal shortening accommodates 3-5 mm/yr of strain transfer across the Denali fault system. Two appendices contain additional results of paleoseismic trenching and neotectonic investigations across 4 active faults near the Nenana River. This dissertation includes previously unpublished co-authored material. / Committee in charge: Ray Weldon, Chairperson, Geological Sciences; Joshua Roering, Member, Geological Sciences; David Schmidt, Member, Geological Sciences; Douglas Kennett, Outside Member, Anthropology

The Kinsevere mine is a copper deposit located in the Democratic Republic of Congo (DRC), within the Central African Copperbelt. This area is situated in the Katangan basin within the SE portion of the Lufilian Arc, which is a large, arcuate structure that extends from SE Angola, across the DRC, and into NW Zambia. The purpose of this study is to characterise the brittle deformation observed around the Kinsevere copper deposit to lead to an understanding of the deformation history of the area. This is accomplished by analysing fault-slip and fold data to help understand the relationship between regional palaeostress, faulting and folding present in the mine vicinity. This study also attempts to characterise fracture-controlled copper mineralisation within the interpreted geodynamic context of the area. The broader objective of this study is to relate the structural observations from Kinsevere to the deformation history of the Lufilian Arc. This study uses the right dihedral method to analyse four categories of brittle structures. The structural types analysed include slickensided faults, mineralised joints, and unmineralised joints and shear fractures. The data suggests that the palaeostress associated with the formation of brittle structures in the Kinsevere area occurred during three deformation events. The first event is characterised by a compressional stress regime which occurred during the early stage of the Kolwezian phase (D1). The second event is characterised by a strike-slip stress regime that formed as the result of clockwise rotation of the earlier (D1) compressional regime. Two fault-slip vectors were observed on the strike-slip fault planes, indicating that a reactivation occurred during the Monwezian phase (D2). The final structural event was characterised by the development of an extensional stress regime. This was associated with North-South oriented extension and is related to the East African Rift System (D3). These interpreted events correlate well with the geodynamic context related to the Lufilian orogeny. Another line of evidence that supports this structural interpretation is the presence of evaporitic minerals observed in the stratigraphic units surrounding the brecciated zones such as the RAT and the CMN. The structural association of these evaporitic minerals may be related to pre-existing, salt-bearing units, which were dissolved during an early compressive (D1) phase of the Lufilian orogeny. However, the contact between the Grey RAT and the Red RAT (distal from the breccia zones) does not show any evidence of faulting, and in the Kinsevere area the Grey RAT is always observed above the Red RAT. This suggests that the Grey RAT may be the uppermost stratigraphic unit of the RAT subgroup, which contradicts some previously published interpretations. Thus, the current structural architecture was probably formed from a combination of two separate mechanisms, including compression-related salt extrusion and the development of thrust faults and folding resulting from the shortening of the Katangan basin. Based on an analysis of the fracture-controlled mineralisation in the study area, it is shown here that most of the stress tensors indicate that these fractures were induced within the compressional stress regime generated by the Lufilian orogeny. This conclusion supports studies which suggest a multiphase origin for the mineralizing fluids active in the Katangan basin. Thus, the age of the copper mineralisation associated with fractures is interpreted to correlate with the timing of the folding event that occurred during the Lufilian orogeny between 540-550Ma. / Dissertation (MSc)--University of Pretoria, 2012. / Geology / unrestricted