The North Anatolian Fault (NAF) is one of the world&rsquo / s largest active continental strikeslip faults, and forms the northern margin of the Anatolian plate. Although its geologic and geomorphologic features are well defined, crustal deformation and associated seismicity around central segment of the NAF is relatively less-known. In this study, we analyzed locations and focal mechanisms of 172 events with magnitude &ge / 3, which are recorded by 39 broadband seismic stations deployed by the North Anatolian Passive Seismic Experiment (2005-2008). Distribution of the events shows that the local seismicity in the area is widely distributed, suggesting a widespread continental deformation, particularly in the southern block. For the entire data set, P- and S- arrival times are picked and events are relocated using the HYPOCENTER program. Then, relocated events which have a good azimuthal coverage with a maximum gap of 120&deg / and at least 13 P- wave readings are selected and 1-D inversion algorithm, VELEST, is used to derive the 1-D seismic velocity model of the region. The final model with updated locations is later put together to the FOCMEC program, to obtain focal mechanisms solutions. In this step, an iterative scheme is applied by increasing the number of data errors. To obtain more unique solutions, first motions of P and SH v phases are used along with SH/P amplitude ratios. Resultant 109 well-constrained focal mechanisms later used to perform stress tensor inversion across the region. Our focal mechanisms suggest a dominant strike-slip deformation along two major fault sets in the region. In the east, E-W trending splays (Ezinepazari, Almus, and La&ccedil / in Kizilirmak) show right-lateral strike-slip motion similar to the NAF whereas in the west, N-S trending faults (Dodurga, Eldivan) show left lateral strike-slip motion. Overall, stress orientations are found as: maximum principal stress, &sigma / 1, is found to be subhorizontal striking NW-SE, the intermediate principle stress, &sigma / 2, is vertically orientated and the minimum principal stress, &sigma / 3, is found to be NE &ndash / SW striking, consistent with the strike-slip regime of the region.

The northwest part of the North America-Caribbean plate boundary zone is characterized by active, left-lateral strike-slip faults that are well constrained seismically and are corroborated by on- and offshore geologic mapping. The onshore plate boundary zone comprises the Motogua and Polochic fault systems of southern Guatemala which join and continue offshore as the Swan Islands fault zone along the southern edge of the Cayman trough. At the Mid-Cayman spreading center in the central Caribbean Sea, the fault motion is transferred at a 100 km wide left-step in the fault system to the Oriente fault zone. A third system, the Walton fault zone, continues east from the Mid-Cayman Spreading center to define the Gonave microplate. Seafloor features produced by strike-slip faulting along the Swan Islands and Walton fault zones have been imaged and mapped using the SeaMARC II side-scan sonar and swath bathymetric mapping system, single-channel seismic data, multichannel seismic data and 3.5 kHz depth profiles. Structures mapped along the Swan Islands and Walton fault zones include: 1) twenty-six restraining bends and five releasing bends ranging in size from several kilometers in area to several hundred kilometers in area; 2)en echelon folds which occur only within the restraining bends; 3) straight, continuous fault segments of up to several tens of kilometers in length; 4) restraining and releasing bends forming in "paired" configurations; and 5) a fault-parallel fold belt fold and thrust belt adjacent to a major restraining bend. The features observed along the Swan Islands and Walton fault systems are compared to other features observed along other strike-slip fault systems, from which empirical models have previously been derived. Based on the features observed in these strike-slip systems, a rigid plate scenario is envisioned where the geometry of the fault and the direction of plate motion have controlled the types of deformation that have occurred. In a related study, microtectonic features in an area of Neogene extension within the northwestern Caribbean plate were investigated in order to provide insight on the nature of intraplate deformation related to the motion along the plate boundary. Microtectonic features were measured in the Sula-Yojoa rift of northwestern Honduras with the intention of inverting the data to estimate stress states responsible for the observed strains. Data inversion for the estimation of stress states could not be undertaken with the available measurements, however, the observations made can be used to support several existing models for the intraplate deformation as well as to encourage the elimination of other models. / text

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.

Thesis (M.S.)--University of Nevada, Reno, 2007. / "May, 2007." Includes bibliographical references (leaves 155-165). Online version available on the World Wide Web.

Thesis (doctoral)--Universität Potsdam, 2004. / "September 2004"--P. [2] of cover. Vita. Includes bibliographical references (p. [115]-132). Also available via the World Wide Web.

Thesis (Ph. D.)--University of Texas at Austin, 1998. / Vita. Four folded plates in pocket. Includes bibliographical references (leaves 285-303). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph.D.)--Memorial University of Newfoundland, 1996. / Restricted until November 1997. Bibliography: leaves 228-255. Also available online.

Sedimentary rocks in the Mecca Hills record a 3-4 Myr history of basin evolution and deformation within the southern San Andreas fault (SAF) zone. Detailed geologic mapping, measured sections, lithofacies analysis, and preliminary paleomagnetic data indicate that sedimentation and deformation in the Mecca Hills resulted from evolution of local fault zone complexities superimposed on regional subsidence and uplift. Sediment was derived from sources northeast of the SAF and transported southeast along the fault zone in large rivers, alluvial fans, and a smaller fault-bounded lake. Inversion of the Painted Canyon fault from oblique SW-side down to SW-side up slip was the main control on local deposition and deformation. Regional controls are suggested by an angular unconformity observed in the Mecca and Indio Hills along ~50 km of the SAF and synchronous post-740 ka uplift northeast of the SAF along ~80 km of the fault zone.

Acquérir des informations sur les forts séismes passés est crucial pour anticiper les caractéristiques des forts séismes futurs. Une partie des traces laissées par les forts séismes passés sont enfouies dans les premiers mètres du sol et sont en général révélées par des tranchées de quelques mètres de profondeur ouvertes à travers les failles sismogènes. Bien que pertinente, cette méthode est destructive. L'objectif a été de développer une nouvelle forme de paléosismologie, non destructive, basée sur l'imagerie géoradar pseudo 3D, capable de retrouver ces traces enfouies des séismes passés. Dans ce travail, cinq sites d’étude sont présentés, situés le long de failles actives décrochantes de Nouvelle Zélande. Notre nouvelle approche débute, dans un premier temps, par l’analyse ‘classique’ de la morphologie de surface à partir de données LiDAR et de MNT GPS haute résolution. Ceci nous permet d’identifier l'ensemble des marqueurs morphologiques préservés à la surface et les déplacements horizontaux qu’ils ont enregistrés. Dans un second temps, l’analyse des profils GPR pseudo-3D acquis en chacun des sites révèlent des réflecteurs principaux dans les premiers 5-10 m du sol recoupés par un grand nombre de marqueurs morphologiques, partiellement ou totalement invisibles en surface. La plupart de ces marqueurs enfouis sont coupés et décalés par la faille considérée. Les mesures de ces décalages fournissent des collections denses de déplacements cumulés sur chacune des failles investiguées avec généralement un nombre de mesures effectués en sub-surface 10 à 20 fois plus important qu’en surface et couvrant une plus large gamme de valeurs. L’application sur la faille de Hope de cette approche a notamment permis de mettre en évidence un déplacement latéral caractéristique de 3.2 ± 1 m lors des 30-35 derniers forts séismes. Ce travail démontre le potentiel de l'imagerie géoradar pseudo-3D à détecter une partie de l'histoire sismique des failles et, ce faisant, à fournir des informations sur les caractéristiques des forts séismes passés. / Collecting information on past strong earthquakes is crucial to anticipate the characteristics of the future strong earthquakes that threaten us. A part of the traces left by the past earthquakes remains hidden in the first few meters of the ground. Until now, paleoseismological trenches across faults have been used to search for these traces. Though relevant, this method is destructive and allows, at best, detecting the few most recent events. The objective of my PhD work, done in the framework of the ANR project CENTURISK, was to develop a novel form of paleoseismology, of geophysical type, based on multi-frequency, pseudo-3D GPR surveys. The idea is to image at high-resolution the architecture of the first ≈ 10 m of the ground over wide areas along active faults, in order to detect the possibly buried traces, especially the offsets, produced by the last 10-20 strong earthquakes on the fault. We have first developed the approach by adapting the acquisition and processing of GPR data to the selected targets. We have then applied the approach on some of the largest active strike-slip faults in New Zealand, where sedimentation conditions are ideal. Twelve sites were investigated, 5 of them are presented in this work. At each site, we first analyzed the surface morphology in the greatest detail on LiDAR data and high resolution GPS DEMs. This analysis allowed us to identify all the morphological markers preserved at the ground surface, and being offset by the fault. We measured these surface offsets, doing so collecting a dense population of cumulative displacement values. We then surveyed each site with 40-60, 100 and 250 MHz, hundreds of meters long GPR profiles, parallel to the fault and regularly spaced by 5-10 m on either side of the fault trace. At each site, the processing of the GPR data revealed a large number of buried markers – palaeosurfaces and incision features, hidden in the first 5-10 m of the ground. Most of the buried markers were observed cut and laterally displaced by the fault, and these offsets could be measured. The measures provide a dense collection of cumulative offsets on each investigated fault, generally 10-20 times more than ever reported. To analyze these dense surface and sub-surface data collections, we used statistical methods made to define and retain only the best constrained offset values. These best values are separated by slip increments that are directly related to the successive coseismic slips that we search. The entire analysis revealed that the offsets measured in the sub-surface fill the gaps in the surface record, and that the surface offsets are systematically lower than those measured in the sub-surface on the same markers. Additionally, the buried record is longer than the surface record. Applied to the Hope Fault, our novel approach allowed identifying the last 30-35 strong earthquakes that broke the fault, each had produced a lateral offset at surface of 3.2 ± 1 m and got a magnitude ≈ Mw 7.0-7.4. Applied to the Wellington Fault (at Te Marua site), the approach allowed identifying a minimum of 15 past strong earthquakes, each had produced a lateral offset at surface of 3.7 ± 1.7 m and got a magnitude ≈ Mw 6.9-7.6. My PhD work thus confirms the great potential of pseudo-3D Ground Penetrating Radar survey to detect a significant part of the fault seismic history, and thus to provide critical information to determine the displacements and magnitudes of the past strong earthquakes on faults. Applied to seismogenic faults worldwide, in complement to surface approaches, the geophysical GPR paleoseismology should help better assessing seismic hazard.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第22113号 / 理博第4540号 / 新制||理||1652(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)教授 福田 洋一, 教授 岩田 知孝, 准教授 深畑 幸俊 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM