Fault Kinematics

The major tectonic structure of the Lower Silesia Region is connected with the Sudetic Marginal Fault (SMF), which past and contemporary activity has been pointed by many authors. Within the "GEOSUD" project the geodynamic profiles have been set up across the most active tectonic zones covering Sudetes and Fore-Sudetic Block. Repeated every year satellite GPS measurements were carried out on the sites of these profiles during the period 1996-2002. The analysis of the results of these measurements shows that tectonic activity of the SMF zone is still going on, but individual segments of this zone are marked by different character of horizontal movements.

We analysed a nearly 133-km-long portion of the Sudetic Marginal Fault (SMF) in Poland (99.7 km) and the Czech Republic (33.8 km), comprised between Złotoryja in the NW and Jesenik in the SE. The fault trace has been subdivided into fifteen segments showing different orientation (N29°W to N56°W, and even N111°W SE of Złoty Stok), geological setting, length (8.8-22.9 km in Poland and 1.4-7.5 km in the Czech Republic), and height of the fault-and fault-line scarps (5-75 m to 200-360 m). Orientation of the entire fault trace approaches N41°W, and the mountain front sinuosity amounts to 1.051. Individual fault segments bear a flight of two to five tiers of triangular facets, showing differentiated state of preservation and degree of erosional remodelling. The highest triangular facets are confined to Rychlebské (Złote) and Sowie Mts. This tiering points to at least five episodes of uplift of the SMF footwall, starting shortly after 31 Ma, i.e. after basalts of the Sichów Hills area were displaced by the fault, and most probably postdating 7-5 Ma time interval, during which rapid cooling and exhumation of the Sowie Góry Mts. massif took place. Morphometric parameters of 244 small catchment areas of streams that dissect the fault scarp include, i.a. elongation, relief, and average slope of individual catchment areas, together with values of the valley floor width to valley height ratios. These figures point to moderate tectonic activity of the SMF and allow us to conclude about Quaternary uplift, particularly important in the Sowie and Rychlebské (Złote) segments.

We analysed a nearly 133-km-long portion of the Sudetic Marginal Fault (SMF) in Poland (99.7 km) and the Czech Republic (33.8 km), comprised between Złotoryja in the NW and Jesenik in the SE. The fault trace has been subdivided into fifteen segments showing different orientation (N29°W to N56°W, and even N111°W SE of Złoty Stok), geological setting, length (8.8-22.9 km in Poland and 1.4-7.5 km in the Czech Republic), and height of the fault-and fault-line scarps (5-75 m to 200-360 m). Orientation of the entire fault trace approaches N41°W, and the mountain front sinuosity amounts to 1.051. Individual fault segments bear a flight of two to five tiers of triangular facets, showing differentiated state of preservation and degree of erosional remodelling. The highest triangular facets are confined to Rychlebské (Złote) and Sowie Mts. This tiering points to at least five episodes of uplift of the SMF footwall, starting shortly after 31 Ma, i.e. after basalts of the Sichów Hills area were displaced by the fault, and most probably postdating 7-5 Ma time interval, during which rapid cooling and exhumation of the Sowie Góry Mts. massif took place. Morphometric parameters of 244 small catchment areas of streams that dissect the fault scarp include, i.a. elongation, relief, and average slope of individual catchment areas, together with values of the valley floor width to valley height ratios. These figures point to moderate tectonic activity of the SMF and allow us to conclude about Quaternary uplift, particularly important in the Sowie and Rychlebské (Złote) segments.

Lower Silesia was broken into numerous tectonic blocks, graben and horsts during late Alpine orogeny. These movements were at its peak in the Neogene. Througout the Quaternary till present times this activity wakened, nevertheless their existence is still felt as local earthquakes. The area of SW Poland is characterised by dense settlement and development resulting from favourable climatic and soil conditions and abundant mineral resources. Numerous engineering objects: water dams, mines, city agglomerations have been built. Some of water dams have been located in tectonic zones, whose activity was confirmed by geological studies. This creates possible threat for people living there. Within successive projects a geodetic monitoring system, based on satellite GPS, geodetic, gravimetric and relative (feeler gauge) observations, in "geodynamic profiles" connected by means of GPS network, has been developed. Multiple measurements indicate differentiated crustal movements in the investigated area, particularly in young tectonic graben. Analysis of changes determined from geodetic observations will help selecting dams and water reservoirs with potentially greatest degree of hazard.

Crustal Structure Convener:*Ayako Nakanishi(Institute for Frontier Research on Earth Evolution, Japan Agency for MarineEarth Science and Technology), Chair:Ayako Nakanishi(Institute for Frontier Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology) Wed. Apr 30, 2014 2:15 PM 4:00 PM 315 (3F) The aim of this session is to cover seismological and geophysical studies on the Earth's crust. Contribution on seismological and geophysical structure of the crust, processes that develop in the crust which include earthquakes, volcanoes and geological descriptions of the crust are welcomed. We also welcome theoretical and methodological studies that will serve as basics in such explorations.

The Eastern Branch of the East African Rift System is well known in Ethiopia (Main Ethiopian Rift) and Kenya (Kenya or Gregory Rift) and is usually considered to fade away southwards in the North Tanzanian Divergence, where it splits into the Eyasi, Manyara and Pangani segments. Further towards the south, rift structures are more weakly expressed and this area has not attracted much attention since the mapping and exploratory works of the 1950s. In November 4, 2002, an earthquake of magnitude Mb = 5.5 struck Dodoma, the capital city of Tanzania. Analysis of modern digital relief, seismological and geological data reveals that ongoing tectonic deformation is presently affecting a broad N-S trending belt, extending southward from the North Tanzanian Divergence to the region of Dodoma, forming the proposed ''Manyara-Dodoma Rift segment". North of Arusha-Ngorongoro line, the rift is confined to a narrow belt (Natron graben in Tanzania) and south of it, it broadens into a wide deformation zone which includes both the Eyasi and Manyara grabens. The two-stage rifting model proposed for Kenya and North Tanzania also applies to the Manyara-Dodoma Rift segment. In a first stage, large, well-expressed topographic and volcanogenic structures were initiated in the Natron, Eyasi and Manyara grabens during the Late Miocene to Pliocene. From the Middle Pleistocene onwards, deformations related to the second rifting stage propagated southwards to the Dodoma region. These young structures have still limited morphological expressions compared to the structures formed during the first stage. However, they appear to be tectonically active as shown by the high concentration of moderate earthquakes into earthquake swarms, the distribution of He-bearing thermal springs, the morphological freshness of the fault scarps, and the presence of open surface fractures. Fault kinematic and paleostress analysis of geological fault data in basement rocks along the active fault lines show that recent faults often reactivate older fault systems that were formed under E-W to NW-SE horizontal compression, compatible with late Pan-African tectonics. The present-day stress inverted from earthquake focal mechanisms shows that the Manyara-Dodoma Rift segment is presently subjected to an extensional stress field with a N080°E direction of horizontal principal extension. Under this stress field, the rift develops by: (1) reactivation of the pre-existing tectonic planes of weakness, and (2) progressive development of a new fault system in a more N-S trend by the linkage of existing rift faults. This process started about 1.2 Ma ago and is still ongoing.

The Kunlun fault is one of the major strike-slip faults accommodating the eastward escape of the Tibetan plateau as a result of the India/Eurasia collision. During the last hundred years, several segments have ruptured through large earthquakes with magnitude from 6.1 to 7.5 ...

This paper describes in detail a spectacularly exposed transpressional imbricate zone from the Southern Uplands of SE Scotland. A highly heterogeneous assemblage of contemporaneous structures is preserved and is interpreted to have formed during bulk inclined triclinic sinistral transpression in an obliquely convergent thrust wedge. The resulting structures include a piggy-back imbricate system of closely related strike-slip detachments, highly curvilinear folds, oblique thrust faults and a clockwise-transecting cleavage. A series of sub-domains are recognised, which are interpreted to result from imperfect kinematic partitioning of the bulk transpression into either contraction-or wrench-dominated strains. In this case, the partitioning appears to be controlled by pre-existing lithological anisotropy and how this was subsequently modified by processes such as folding once deformation began. Our findings demonstrate that transpressional deformation zones can develop structural patterns geometrically very similar to those found in dip-slip fold and thrust belts. Such geometries are likely to occur in many other obliquely convergent wedges because deformation zone boundaries are very often inclined and lie at low-angles or subparallel to regional bedding. Imbricate systems inevitably form because the sedimentary anisotropy is a key mechanical control in their development. Our observations illustrate, therefore, the fundamental importance of measuring fault movement directions in the field using fault slickenline lineations in imbricate systems. It is possible that a number of 'imbricate zones' identified in other thrust wedges may turn out to be transpressional features.

Auriferous sediments in the East Sudetic Foreland region include up to five gold-bearing horizons associated with preglacial and Quaternary fluvial sediments. The largest placer potential lies in the preglacial (Eopleistocene?) drainage system, primarily in palaeochannels of the Bia³a G³ucho³aska River. The White Gravel series is the richest gold-bearing horizon. It contains between 0.37 g/m 3 Au near the base and <0.10 g/m 3 Au in its upper part. Maximum gold grade occurs in the first 1-2 m above the contact with the bedrock. Gold concentration in this area was controlled by the ability of streams to aggradation and the development of sedimentologic traps, where gold was accumulated during the preglacial valley erosion. Oblique orientation of the palaeo-Bia³a G³ucho³aska valley and its tributaries to the regional ice-flow direction probably prevented the glaciers from eroding deeply into the palaeochannels. From the exploration prospective, study of palaeochannel systems in the vicinity of Otmuchów-Prudnik could identify other buried placer gold occurrences. Gold-bearing sediments, correlated stratigraphically with the Bia³a G³ucho³aska palaeochannel White Gravels occur in several other areas, including the Nysa K³odzka, Kwisa and Kaczawa valleys.

In January 1988, scientists from over 25 organizations in ! 3 countries and territories cooperated in the largest Global Positioning System (GPS) campaign in t_he world to date (Table !). 43 GPS receivers collected approximately 590 station-days of data in American Samoa,

Presentamos la cronologia de paleoterremotos establecida para la rama sur de la Falla de Alhama de Murcia (Beticas Orientales) a partir del estudio paelosismologico de la localidad de el Saltador (Lorca). Mostramos la aplicacion combinada de cuatro metodos de datacion; luminiscencia en cuarzo y feldespato (OSL en cuarzo y pIRIRSL), datacion de series de Uranio en carbonatos pedogenicos, y radiocarbono. Para acotar la edad de los paleoterremotos con la mejor definicion posible, se han integrado las edades de las capas que definen temporalmente los paleosismos en un modelo deposicional. Para ello se uso el programa OxCal (version 4.2), que realiza un tratamiento estadistico bayesiano de las funciones de probabilidad de las edades de materiales afectados segun un orden estratigrafico conocido y calcula la recurrencia media y la recurrencia particular entre eventos sucesivos. La secuencia de materiales aluviales muestra el registro de ocho eventos paleosismicos ocurridos desde hace 54,3...

s of invited lectures (IL, 60 minutes including discussion), regular talks (RT, 15 min max), flash talks (FT, 5 min max), and poster presentations (PO) are collected here. Those flash talks that have a companion poster are coded as FT/PO. The invited lectures will be available on the workshop webpage http://fault2sha.net/4th-workshop/ after the meeting. Participant contributions are subdivided in the three sessions, and listed in alphabetical order. Please note that all the authors are asked to summarize their topics in a poster, to facilitate informal discussion. Posters will eventually be available online after the meeting too.

The Argentera Massif (French-Italian Alps), with its uniform lithology, was selected to evaluate how known Plio-Pleistocene tectonics have conditioned the drainage network geometry. The drainage network was automatically derived and ordered from a 10 m-resolution DEM. On hillshade images, alignments of morphological features were identified. The Massif was subdivided into 22 domains of 50 km 2 within which the directions of every river channel segment and the direction of the aligned morphological features were compared and contrasted with the strike of tectonic structures measured in the field. Results suggest that the Argentera drainage system is variously controlled by recent tectonics, depending on the Massif sector taken into account. In the NW sector, the vertical uplift is less because the strain has been accommodated in an oblique direction along a lateral thrust. In the SE sector, strain in a predominantly vertical direction along a frontal thrust has resulted in a major vertical displacement. Accordingly, the NW sector is characterized by (i) a strong geometric relationship between the main tectonic structures and the directions of river channels, (ii) longitudinal main rivers bordering the Massif, and (iii) a general trellis pattern within the domains. In the SE sector, the prolonged uplift has forced an original longitudinal drainage system to develop as a transverse system. This change has occurred by means of fluvial captures that have been identified by the presence of windgaps, fluvial elbows and knickpoints. At the domain scale, intense uplift of the SE sector has prompted the drainage pattern to evolve as a dendritic type with no clear influence of structure in the channel orientations.

On February 8, 2025, a remote area in the Caribbean Sea was rocked by a large Mw 7.6 (USGS, 2025) earthquake, centered 209 km SSW of Georgetown, the capital of the Cayman Islands and the largest city (population ~41,000) of the British Overseas Territories (Figure 1). The earthquake was significant due to its large magnitude, potential regional impact, and the possibility of generating a tsunami. This was the largest strike-slip earthquake ever recorded (i.e., since the advent of instrumental seismology) along the northern Caribbean Plate boundary, with most earthquakes reaching only the low Mw 7 ’ s range (ten Brink et al., 2011). While there are no known casualties or significant damage because of the remoteness of the epicenter, the complex but well-studied tectonic setting of the earthquake along the transform (strike-slip or sideways motion) separating the North American and Caribbean plates has major implications for understanding hazards associated with other plate and micro-plate boundaries around the world, including SE Asia.

Several swath profiles, drainage morphometric parameters, slope and drainage density maps were obtained by DTM analysis of the Argentera Massif (Western Alps). The spatial distribution of the analysed parameters indicates that the central-southern sector is characterized by orographic and drainage characteristics very different from the rest of the Massif. Two main systems of NW-and WNW-trending faults, the Orgials Fault and Valletta Fault, bound this area. Both faults belong to large-scale fault zones: the dextral strike-slip Bersezio Fault and the south-facing Colle del Sabbione thrust. The orientations and kinematics of both faults indicate a late Alpine (Pliocene to recent) SW-verging thrusting coupled with a dextral strike-slip movement. The central-southern sector of the Massif corresponds to the hanging wall of a SW-verging late Alpine thrust zone, and underwent the highest post Pliocene tectonic uplift in the Argentera Massif. The uplift occurred in a transpressive setting with an N-S shortening direction, which is consistent with the post-Pliocene tectonics in the southern portion of the Western Alps.

This paper describes in detail a spectacularly exposed transpressional imbricate zone from the Southern Uplands of SE Scotland. A highly heterogeneous assemblage of contemporaneous structures is preserved and is interpreted to have formed during bulk inclined triclinic sinistral transpression in an obliquely convergent thrust wedge. The resulting structures include a piggy-back imbricate system of closely related strike-slip detachments, highly curvilinear folds, oblique thrust faults and a clockwise-transecting cleavage. A series of sub-domains are recognised, which are interpreted to result from imperfect kinematic partitioning of the bulk transpression into either contraction-or wrench-dominated strains. In this case, the partitioning appears to be controlled by pre-existing lithological anisotropy and how this was subsequently modified by processes such as folding once deformation began. Our findings demonstrate that transpressional deformation zones can develop structural patterns geometrically very similar to those found in dip-slip fold and thrust belts. Such geometries are likely to occur in many other obliquely convergent wedges because deformation zone boundaries are very often inclined and lie at low-angles or subparallel to regional bedding. Imbricate systems inevitably form because the sedimentary anisotropy is a key mechanical control in their development. Our observations illustrate, therefore, the fundamental importance of measuring fault movement directions in the field using fault slickenline lineations in imbricate systems. It is possible that a number of 'imbricate zones' identified in other thrust wedges may turn out to be transpressional features.

Se recopila una base de datos de 2547 mecanismos focales de terremotos para modelar el campo de esfuerzo tectónico en Costa Rica, sur de Nicaragua y norte de Panamá. Se determinan 86 tensores regionales de esfuerzo. La orientación general del esfuerzo horizontal máximo (SH Max) es subparalela a la dirección de convergencia N 32° E de la placa de Cocos con la placa Caribe a lo largo de la fosa mesoamericana, con una rotación horaria de +-20° por debajo de los 30 km de profundidad. Se identifican tres órdenes de esfuerzos: el primero debido al movimiento absoluto de la placa de Cocos, el segundo generado por la interacción triple de esta con las placas Caribe y Nazca, y el tercero debido a contrastes de densidad impuestos por las cordilleras volcánicas, ígneas y sedimentarias activas y paralelas a la fosa, las cuales en combinación con fallas regionales y sus interacciones, actúan en conjunto como deflectores de los esfuerzos tectónicos locales que rotan hacia el norte y oeste. Los datos GNSS observados y modelados del campo de velocidades horizontales, orientados al NNE, presentan una correlación notable con las direcciones del SH Max interpoladas en la capa superior. Estas características, junto con las permutaciones locales y regionales de los ejes del elipsoide de esfuerzos, explican las interacciones de los regímenes tectónicos y sus complicaciones neotectónicas. Se genera un escenario 2D-3D detallado con límites sismo tectónicos realistas y más objetivos, utilizando categorías de regímenes de esfuerzo junto con la relación tectónica R'. Los resultados tienen aplicación práctica en estudios de amenaza y riesgo sísmico, exploración de recursos naturales.

Located in central Europe at the junction of the Southern Alps and the Dinarides, the ≈ 100 km long Idrija fault, striking N310 and dipping ≈ 80°NE is often considered as the potential source of the historical 1511 earthquake (estimated macroseismic magnitude: Mm 6.8). Using 1/25000 to 1/5000 topographical maps, satellite images (SPOT5), 12.5 m illuminated DEM and airborne LiDAR data-derived 1-m-DEM, we examined in detail the Idrija fault trace along a 20-km-long swath in the central portion of the fault.

The morphology of the marginal part of the Sudetes between Dobromierz and Paszowice reflects above all lithological and structural differences within bedrock. Major landforms include watershed surfaces of low relief, monadnocks and intramontane basins. Drainage pattern changes were associated with the decay of the early Saalian (Odranian) ice-sheet, whilst stages of further development of fluvial systems are well documented by multiple terrace levels. The mountain front of the Sudetes, genetically related to the Sudetic Marginal Fault, is only up to 100 m high and overall strongly degraded. In contrast to southern sectors of the Sudetic mountain front, active Quaternary tectonics played minor part in the landscape development.

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

We are undertaking a cooperative geodetic experiment in Trinidad and Tobago to quantify historic and current strain rates and their distributions in this part of the Caribbean (Ca)-South American (SA) plate boundary zone (pbz). In May and June of 1994 we re-measured, with GPS (Global Positioning System), ~10 recently recovered first-order monuments from a historic triangulation network built and originally measured by the British Ordinance Survey in 1901-03 across Trinidad. We also establish new baselines from these historic marks to several monuments in Tobago, from which we can monitor motions with second-epoch and subsequent GPS campaigns. Our objectives are to constrain the rate and direction of Ca-SA motion in the ppz. These data, which are now lacking, are critical in the establishment of earthquake hazard exposure levels in the region. The low level of shallow «50 km) seismicity, at all magnitudes, in Trinidad and Tobago since 1953 indicates that lithospheres in this portion of the pbz are either: (I) not straining or straining at a very low rate; or (2a) they are straining completely aseismically (creeping) or (2b) straining away from locked faults with large seismic potentials.

Trinidad and Tobago sits in an actively deforming plate boundary. Active structures are currently being explored for petroleum, engineered, and built across. By applying GPS (Global Positioning System), paleoseismology, Quaternary geology, and geomorphology techniques we are beginning to understand the kinematics, history, and seismic risk of some of these active structures. This new geodetic and geologic information should be included in updates to the current earthquake-only-based national seismic risk map. There are at least three principal active faults in Trinidad and Tobago: 1) the Central Range dextral-transpressive transform fault, and 2) the Los Bajos dextral-oblique (?) fault, and 3) the North Coast/South Tobago normal-dextral fault system.

The Muertos Deformed Belt (MDB) is a tectonic feature located within the Northeastern Caribbean Plate Boundary Zone. This deformed belt is occupying a broad band of active compression regime with an east-west trend along the south of Hispaniola and Puerto Rico islands. In our survey area, the deformed belt is limited to the south by the Muertos Trough (>5500 m depth), where the Venezuelan Basin oceanic crust is being underthrusted beneath western Puerto Rico and eastern Hispaniola areas. Here, we present the morphotectonic interpretation from the multibeam systematic survey in Muertos Deformed Belt area (from GEOPRICO-DO marine geophysical survey (2005)) and the relationship with seismicity and kinematic data (GPS). Active deformation features have been widely found in the area from bathymetry model and Chirp sub-bottom seismic profiles (TOPAS). These features include: folded and faulted recent sediments (Holocene), submarine landslides scars associated with faults (tsunamogenic potential) and submarine canyons deflected by fault traces. All these features are well preserved and show a little erosion. Future works will integrate potential field data and deep seismic data, which will allow us to elaborate complete tectonic models for this active and complex plate boundary.

Several swath profiles, drainage morphometric parameters, slope and drainage density maps were obtained by DTM analysis of the Argentera Massif (Western Alps). The spatial distribution of the analysed parameters indicates that the central-southern sector is characterized by orographic and drainage characteristics very different from the rest of the Massif. Two main systems of NW-and WNW-trending faults, the Orgials Fault and Valletta Fault, bound this area. Both faults belong to large-scale fault zones: the dextral strike-slip Bersezio Fault and the south-facing Colle del Sabbione thrust. The orientations and kinematics of both faults indicate a late Alpine (Pliocene to recent) SW-verging thrusting coupled with a dextral strike-slip movement. The central-southern sector of the Massif corresponds to the hanging wall of a SW-verging late Alpine thrust zone, and underwent the highest post Pliocene tectonic uplift in the Argentera Massif. The uplift occurred in a transpressive setting with an N-S shortening direction, which is consistent with the post-Pliocene tectonics in the southern portion of the Western Alps.

New stratigraphic data, lithostratigraphic correlations, and fault kinematic analysis are used to discuss the basin geometry and sedimentation patterns of the northeastern Tunisia during Cretaceous times. Significant facies and thickness variations are deduced along the northeastern Atlas of Tunisia. The NW-SE 80-km-long regional correlation suggests a high sedimentation rate associated with irregular sea floor. The fault kinematic analysis highlights N-S to NE-SW tectonic extension during Early Cretaceous. During Aptian-Albian times, an extensional regime is recognized with NE-SW tectonic extension. The Cenomanian-Turonian fault populations highlight a WNW-ESE to NW-SE extension, and Campanian-Maastrichtian faults illustrate an NW-SE extension. The normal faulting is associated to repetitive local depocenters with a high rate of sedimentation as well as abundant syntectonic conglomeratic horizons, slump folds, and halokinetic structures. The sequence correlation shows repetitive local depocenters characterizing the basin during Early Cretaceous times. All the above arguments are in favor of basin configuration with tilted blocks geometry. This geometry is shaped by major synsedimentary intra-basin listric normal faults, themselves related to the extensional setting of the southern Tethyan paleomargin, which persisted into the Campanian-Maastrichtian times. The results support a predominant relationship between tilted blocks geometry and sedimentation rather than E-W BTunisian trough^as it was previously accepted.

Tectonic deformations in the southern Atlassic front of Tunisia (SAFT) and the Gulf of Gabes result from the Nubia-Eurasia convergence. This study, based on the inversion of geologically determined fault slip vectors, presents evidences for spatial and temporal changes in the stress state. Fault kinematics analyses reveal a temporal change in states of stress during the Late Cenozoic. A paleostress (Miocene-Pliocene) state is characterized by a regional compressional tectonic regime with a mean N134 ± 09°E trending horizontal maximum stress axis (σ 1). A modern (Quaternary to present-day) state of stress also corresponds to compressional tectonic regime with a regionally mean N05 ± 10°E trending horizontal σ 1. The SAFT corresponds to two distinct domains: a far-foreland Atlassic front related to contractional deformation associated with southward propagate thrusting, and eastward, the Gulf of Gabes characterized by normal component NW to WNW trending faults at the crustal margin scale probably related with a transtensional tectonic regime. We propose that the spatial and temporal changes in the stress during the Miocene-Pliocene and Quaternary may result from the geodynamic evolution of the Tunisian Atlas in relation to the rotation of Corsica-Sardinia blocks and the separation of the Sicilian continental lithosphere from the Ionian oceanic lithosphere. These temporal and spatial stress changes along the SAFT and the Gulf of Gabes are probably the engine behind the moderate seismicity, leading at the same time to a reactivation of the inherited major structures created during the evolution of the southern Tethyan margin.

Fallas normales de alto ángulo en el Neógeno del margen Atlántico de la Cuenca del Golfo San Jorge (46ºS-67º 30´O, Patagonia Argentina) R.E. Giacosa (1)(2) , J.M. Paredes (2) , A.M. Nillni (2) , M. Ledesma (2)(3) y F. Colombo (4) (1) Servicio Geológico Minero Argentino. CC 38 B, Km 8 (A-9003).

A database containing 2547 earthquake focal mechanisms from Costa Rica, southern Nicaragua, and northern Panama is
analyzed to model the modern tectonic stress field through inversion. 86 regional stress tensors are derived, revealing the general
orientation of the maximum horizontal stress (SH Max) to be sub-parallel to the N 32° E convergence direction of the Cocos plate
with the Caribbean plate along the Middle America Trench. A clockwise rotation of approximately ±20° is observed below 30 km
depth. Three orders of stress are identified: the first attributed to the absolute motion of the Cocos plate, the second characterized
by high magnitude boundary forces from the triple interaction of the Cocos plate with the Caribbean and Nazca plates, and the
third due to density contrasts imposed by trench-parallel active volcanic, igneous, and sedimentary mountain ranges. These featu
res, combined with regional faults and their interactions, deflect the local tectonic stress north and westward. Observed and mo
delled GNSS data of the NNE-oriented horizontal velocity field correlate well with the direction of interpolated SH Max in the
upper layer. These findings along with the local and regional permutations of the stress axes ellipsoid elucidate the interactions of
tectonic regimes and their neo-tectonic complications. A detailed 2D-3D scenario is generated, offering realistic seismotectonic
boundaries using stress regime categories and the tectonic R' relationship. The results hold significant practical implications for
seismic hazard and risk assessment, as well as the exploration and exploitation of natural resources.
Keywords: focal mechanism, inversion, stress tensor, permutation, stress orders

The Neogene Alasehir supradetachment basin in western Turkey occurs in the footwall of the modern Alaşehir-Gediz graben and is a major component of the Aegean extensional province in Anatolia that developed during the late Cenozoic exhumation of the Menderes core complex. The size, geometry, accommodation space and internal structure-stratigraphy of this basin were strongly controlled by the kinematics and interplay of four different fault generations throughout its early Miocene-Pleistocene evolution. The ~E-W-striking, NNE-dipping (10°-30°) Alaşehir detachment fault separates the high-grade crystalline rocks of the core complex below from the Neogene deposits of the basin in the hanging wall above. The basin-parallel, synthetic and antithetic high-angle normal faults represent a block-faulting stage of the continued horizontal extension that terminated the northerly slip along the detachment surface and produced horstgraben structures in and across the basin. These faults were also responsible for the back-tilting of the basinal strata into steeper dips and the rotation of the previously formed faults into gently dipping planes. The mutually crosscutting relationships between the intra-basinal low-angle and basement-involved high-angle and normal faults indicate their contemporaneous development and operation. The NNE-striking, basin-perpendicular oblique-slip hinge faults are reminiscent of transfer (cross) faults in both continental and oceanic extension, and divide the supradetachment basin into a series of fault blocks with their own internal structure and stratigraphy. Differential uplift and exhumation of the core complex rocks along these hinge faults and the varied displacement and slip along and across them within the basinal strata caused differential extension and block-uplift, leading to the formation of local unconformities in the supradetachment basin. Significant changes in the dip directions and strike orientations of the sedimentary beds and the observed deviations from the inferred direction of maximum extension in the adjacent fault blocks resulted from rotational deformation due to hinge faulting. Fault segmentation of the Alaşehir basin as a result of extension-parallel hinge-faulting is a characteristic feature of its supradetachment basin evolution.

Minor fault geometry and kinematics within relay ramps is strongly related to the stress field perturbations that can be produced when two major fault segments overlap and interact. Here we integrate classical fieldwork and interpretation of a virtual outcrop to investigate the geometry and kinematics of subsidiary faults within a relay ramp along the Tre Monti normal fault in the Central Apennines. Although the Tre Monti fault strikes parallel to the regional extension (NE-SW) it shows predominant dip-slip kinematics, suggesting a NW-SE oriented extension acting at sub-regional scale (1-10 km). Conversely, the slickenlines collected on the front segment of the relay ramp highlight right-lateral kinematics. The subsidiary faults in the relay ramp show a complex geometry (variable attitudes) and slickenlines describe multiple kinematics (left-lateral, dip-slip, right-lateral), independently of their orientation. Our fault slip analysis indicates that a local stress field retrieved from the kinematic inversion of the slickenlines collected on the front segment, and likely promoted by the interaction between the overlapping fault segments that bound the relay zone, can explain most of the geometry and kinematics of the subsidiary faults. Further complexity is added by the temporal interaction with both the regional and subregional stress fields.

Minor fault geometry and kinematics within relay ramps is strongly related to the stress field perturbations that can be produced when two major fault segments overlap and interact. Here we integrate classical fieldwork and interpretation of a virtual outcrop to investigate the geometry and kinematics of subsidiary faults within a relay ramp along the Tre Monti normal fault in the Central Apennines. Although the Tre Monti fault strikes parallel to the regional extension (NE-SW) it shows predominant dip-slip kinematics, suggesting a NW-SE oriented extension acting at sub-regional scale (1-10 km). Conversely, the slickenlines collected on the front segment of the relay ramp highlight right-lateral kinematics. The subsidiary faults in the relay ramp show a complex geometry (variable attitudes) and slickenlines describe multiple kinematics (left-lateral, dip-slip, right-lateral), independently of their orientation. Our fault slip analysis indicates that a local stress field retrieved from the kinematic inversion of the slickenlines collected on the front segment, and likely promoted by the interaction between the overlapping fault segments that bound the relay zone, can explain most of the geometry and kinematics of the subsidiary faults. Further complexity is added by the temporal interaction with both the regional and subregional stress fields.

In the peri-Mediterranean metamorphic belts, the tectonic evolution of the Calabria–Peloritani terrane during the dominant compressive tectonics of the Eocene represents one of the most problematic points in palinspastic restorations. A matter of particular debate is its shortening, which could have occurred during the Alpine or the Apennine subduction. In this regard, a crucial joint is provided by the kinematics of one of the most relevant shear zones such as the Curinga–Girifalco Line, cropping out in central Calabria. This shear zone juxtaposed a nearly complete Hercynian crustal section (i.e. the Sila and Serre Unit) onto the remnants of the Castagna Unit. The data in the available literature on ductile kinematics from the south-eastern branch of the Curinga–Girifalco Line indicate a downward movement of the hanging wall. In the present paper we show new, ductile kinematic data and petrographic evidence from outcrops in the north-western and south-eastern branches of the Curing...

Nowadays long continuous time series of products obtained by GNSS (Global Navigation Satellite Systems) measurements are available. Due to reprocessing efforts these time series have achieved a very high consistency level. In this context the analysis, reassessment, and the interpretation of these time series become more and more important. In particular station coordinate time series from GNSS observations may be affected by discontinuities, e.g., because of equipment changes, earthquakes, other geophysical processes, data problems, and environmental effects. In the Bernese GPS Software the program ADDNEQ2 is responsible to combine individual (e.g., daily or weekly) solutions over a long time interval of even ten years and more. Regarding the fact that today usually between 100 and 200 (or even more) stations are included in a continuous processing schema over years, an automated analysis of the time series is very appreciated. FODITS (find ōutliers and discontinuities īn time series) has been developed as a new tool of the Bernese GPS Software. A functional model including outliers, discontinuities, one or more linear velocities per station, and a set of periodic functions is adapted by the program to the time series of the data according to the significance of the components. The used algorithm is bases on the ATI (adaptation, test, and identification) method-developed for preprocessing of GNSS data-and is optimized for the analysis of long time series of coordinates. Nevertheless, it is also possible to analyse other time series using FODITS. In this paper we present examples of analysed time series of station coordinates and differential code biases.

We use Global Navigation Satellite Systems observations in northeastern Venezuela to constrain the El Pilar Fault (EPF) kinematics and to explore the effects of the variable elastic properties of the surrounding medium and of the fault geometry on inferred slip rates and locking depth. The velocity field exhibits an asymmetric velocity gradient on either side of the EPF. We use five different approaches to explore possible models to explain this asymmetry. First, we infer a 1.6 km locking depth using a classic elastic half‐space dislocation model. Second, we infer a 1.5 km locking depth and a 0.33 asymmetry coefficient using a heterogeneous asymmetric model, including contrasting material properties on either side of a vertical fault, suggesting that the igneous‐metamorphic terranes on the northern side are ~2 times more rigid than the sedimentary southern side. Third, we use a three‐dimensional elastostatic model to evaluate the presence of a compliant zone, suggesting a 30% reduct...

The NW-SE striking Sudetic Marginal Fault (SMF) is one of the most conspicuous tectonic structures in central Europe. It controls the pronounced morphotectonic escarpment of the Sudetic Mountains for a length of 130 km. This paper presents the results of trenching on the SMF, undertaken in order to assess activity of the fault. The trenching technique has not hitherto been applied on either this particular fault system or elsewhere in the Bohemian Massif. However, it is the most effective tool for near-surface fault investigation in areas that are well vegetated and therefore devoid of fault outcrops. Moreover, the study area is situated in an intraplate region with a low displacement rate, which is exceeded by an erosion rate and does not favor the preservation of fault scarps. The trench sites were selected from prior DEM analyses, geomorphological fieldwork, and geophysical sounding. The trenches exposed a range of lithologies of Variscan crystalline rocks and Caenozoic sediments. At least four phases of faulting have been distinguished based on structural data, succession and age of the deformed sediments. Reverse faulting (N160°E), which displaced the Miocene sediments over the crystalline rocks, postdates their deposition (15 Ma) and pre-dates Late Glacial gelifluction. Horizontal movements that have affected the Miocene deposits along a structure striking N35°E have the same wide time constraint. Younger reverse faulting, which caused a co-seismic relief step, postdates the Late Glacial gelifluction but preceded the early Holocene colluvium deposition (10,940 ± 140 cal yrs BP). Normal faults striking N145°E, which cut the Miocene unit, might have been reactivated after the early Holocene colluvial sedimentation but before the buried soil (430 ± 120 cal yrs BP). Moreover, based on the identified prehistoric earthquake, respective minimum moment magnitude M 6.3 and slip rate 0.03 mm/year were estimated.

Transpressive deformation at the northern Caribbean plate boundary is accommodated mostly by two major strikeslip faults, but the amount and location of accommodation of the compressional component of deformation is still debated. We collected marine geophysical data including multi-beam bathymetry and multichannel seismic reflection profiles along this plate boundary around Hispaniola, in the Jamaica Passage and in the Gulf of Gonâve. The data set allows us to image the offshore active strike-slip faults as well as the compressional structures. We confirm that the Enriquillo-Plantain-Garden Fault Zone (EPGFZ) in the Jamaica Passage has a primary strike-slip motion, as indicated by active left-lateral strike-sliprelated structures, i.e.: restraining bend, asymmetrical basin, en echelon pressures ridges and horsetail splay. Based on topographic cross-sections across the EPGFZ, we image a very limited compressional component, if any, for at least the western part of the Jamaica Passage. Toward the east of the Jamaica Passage, the fault trace becomes more complex and we identify adjacent compressional structures. In the Gulf of Gonâve, distributed folding and thrust faulting of the most recent sediments indicate active pervasive compressional tectonics. Estimates of shortening in the Jamaica Passage and in the Gulf of Gonâve indicate an increase of the compressional component of deformation towards the east, which nonetheless remains very small compared to that inferred from block modelling based on GPS measurements.

Nowadays, detecting the response level of ground shaking and studying its effect on the measurements of the surface motion are considered very important, because of the spread of natural disasters, such as earthquakes, volcanoes, and tsunamis. Such disasters lead to changes in the Earth's crust and hence movements of some points. Therefore, studying these movements has great benefits, such as the ability to predict the occurrence of an earthquake, which helps to control and minimize human and economic damages. It is possible to evaluate accurately the magnitude of point displacements and to find the factors affecting these displacements. In this research work, we explain the seismic monitoring techniques using the global navigation satellite system (GNSS), which considered a powerful tool for monitoring the ground points displacements, Bernese GNSS Software 5.2[4], was used to obtain high-precision of the results of the IGS stations data and their displacements, with the application on the network stations in the study area of Turkey,(Aegean sea earthquake).

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This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright

Seismo-stratigraphic and structural analysis of a large number of multichannel seismic reflection profiles acquired in the northern part of the Sicilian Channel allowed a 3-D reconstruction of a regional NS-trending transfer zone which displays a transcurrent tectonic regime, and that is of broad relevance for its seismotectonic and geodynamic implications. It is constituted of two major transcurrent faults delimiting a 30-km-wide, mostly undeformed basin. The western fault (Capo Granitola) does not show clear evidence of present-day tectonic activity, and towards the south it is connected with the volcanic area of the Graham Bank. The eastern fault (Sciacca) is structurally more complex, showing active deformation at the sea-floor, particularly evident along the Nerita Bank. The Sciacca Fault is constituted of a master and splay faults compatible with a right-lateral kinematics. Sciacca Fault is superimposed on an inherited weakness zone (a Mesozoic carbonate ramp), which borders to the east a 2.5-km-thick Plio-Quaternary basin, and that was reactivated during the Pliocene. A set of scaled claybox analogue models was carried out in order to better understand the tectonic processes that led to the structural setting displayed by seismic data. Tectonic structures and uplift/subsidence patterns generated by the models are compatible with the 3-D model obtained from seismic reflection profiles. The best fit between the tectonic setting deriving from the interpretation of seismic profiles and the analogue models was obtained considering a right-lateral movement for the Sciacca Fault. Nevertheless, the stress field in the study area derived from GPS measurements does not support the present-day modelled right-lateral kinematics along the Sciacca Fault. Moreover, seismic events along this fault show focal mechanisms with a left-lateral component.

The margins of the Caribbean and associated hazards and resources have been shaped by a poorly understood history of subduction. Using new data, we improve teleseismic P-wave imaging of the eastern Caribbean upper mantle and compare identified subducted-plate fragments with trench locations predicted from plate reconstruction. This shows that material at 700-1200 km depth below South America derives from 90-115 Myr old westward subduction, initiated prior to Caribbean Large-Igneous-Province volcanism. At shallower depths, an accumulation of subducted material is attributed to Great Arc of the Caribbean subduction as it evolved over the past 70 Ma. We interpret gaps in these subducted-plate anomalies as: a plate window and tear along the subducted Proto-Caribbean ridge; tearing along subducted fracture zones, and subduction of a volatile-rich boundary between Proto-Caribbean and Atlantic domains. Phases of back-arc spreading and arc jumps correlate with changes in age, and hence buoyancy, of the subducting plate.

In 2005, the SIGMA Program (Mount Aconcagua GNSS Research System) was implemented to investigate the geodynamics of the Aconcagua mountain region in the Central Andes. For this purpose, a continuously recording GPS station, ACON, was installed on the summit of Mount Aconcagua at 6.292 m a.s.l. The installation required special technology to support the equipment under extreme climatic conditions. The power supply system was optimized in 2008, so that a greater quantity of data could be recorded. This, in turn, will lead to more accurate estimates of displacement of the Aconcagua peak. Preliminary results from the ACON station indicate an average horizontal velocity of 0.023±0.0001 m/yr toward NE in 2 time windows between 2006 and 2008.

Spatial configuration of Quaternary active tectonic features along the southern Caribbean plate boundary suggests that the region is subject to a compressive strike-slip (transpressional senso lato) regime, characterized by a NNW-SSE maximum horizontal stress (σ H =σ 1) and/or an ENE-WSW minimum (σ h =σ 3 or σ 2) horizontal stress. Stress inversion applied to fault-plane kinematic indicators measured essentially in Plio-Quaternary sedimentary rocks confirms this tectonic regime. Accordingly, this stress regime is responsible for the Quaternary activity and kinematics of six sets of brittle features along northern Venezuela (from Colombia in the west to Trinidad in the east): (1) east-west rightlateral faults, (2) NW right-lateral faults-acting as synthetic Riedel shears-, (3) ENE to east-west dextral faults-P shears-, (4) NNW normal faults, (5) almost north-south left-lateral faults-antithetic Riedel shears-and (6) mostly subsurface ENE reverse faults associated with folding of the same orientation. Brittle deformation conforms to the simple shear model, although not all the deformation can be accounted for it since strain partitioning is also taking place because regional folding and thrusting are due to the normal-to-structure component of the relative slip vector between the Caribbean and South America plates. On the other hand, the maximum horizontal stress in western Venezuela, particularly in the Maracaibo block and south of the Oca-Ancón fault, progressively turns counterclockwise to become more east-west oriented, producing left-and right-lateral slip along the north-south striking and NE-SW striking faults, respectively. The orientation and spatial variation of this regional stress field in western Venezuela results from the superposition of the two major neighboring interplate maximum horizontal stress orientations (σ H): roughly east-west trending stress across the Nazca-South America type-B subduction along the pacific coast of Colombia and NNW-SSE oriented stress across the southern Caribbean boundary zone.

Analysis of the three-dimensional geometry of Upper Cretaceous clastics in the Muttekopf area (Northern Calcareous Alps, Austria) indicate fold and fault structures active during deposition. Coniacian continental to neritic sedimentation (Lower Gosau Subgroup) was contemporaneous with displacements on NW-trending faults and minor folding along NEtrending axes. From the Santonian onwards (sedimentation of the deep-marine Upper Gosau Subgroup) the NW-trending faults were sealed and large folds with WSW-trending axes developed. The direction of contraction changed to N±S after the end of Gosau deposition in the Danian (Paleocene). Synorogenic sedimentation patterns indicate continuous contraction from the Coniacian to the Late Maastrichtian/?Danian. Therefore, large-scale extension as observed in the central part of the Eastern Alps cannot be documented in the western parts of the Northern Calcareous Alps. A combination of subduction tectonic erosion for the frontal parts and gravitational adjustment of an unstable orogen after nappe stacking for the internal parts possibly accounts for the different development of Gosau basins in the frontal and trailing regions of the Austroalpine wedge.

The El Camp Fault (Catalan Coastal Ranges, NE Iberian Peninsula) is a slow slipping normal fault whose seismic potential has only recently been recognised. New geomorphic and trench investigations were carried out during a training course across the El Camp Fault at the La Porquerola alluvial fan site. A new trench (trench 8) was dug close to a trench made previously at this site (trench 4). With the aid of two long topographic profiles across the fault scarp we obtained a vertical slip rate ranging between 0.05 and 0.08 mm/yr. At the trench site, two main faults, which can be correlated between trenches 8 and 4, make up the fault zone. Using trench analysis three paleoseismic events were identified, two between 34. 000 and 125. 000 years BP (events 3 and 2) and another event younger than 13 500 years BP (event 1), which can be correlated, respectively, with events X (50. 000-125.000 years BP), Y (35.000-50. 000 years BP) and Z (3000-25.000 years BP). The last seismic event at the La Porquerola alluvial fan site is described for the first time, but with some uncertainties.

La depositación de la Formación Salamanca y del Grupo Río Chico (Paleoceno) en la Cuenca del Golfo San Jorge excedió el ámbito de la cuenca continental del Grupo Chubut (Cretácico). Estas unidades muestran cambios estratigráficos significativos en dirección norte-sur para el flanco norte de la cuenca. Por un lado, la acumulación de depósitos bioclásticos basales en la Formación Salamanca (Miembro Bustamante) sólo tuvo lugar en el borde norte de la cuenca, donde la sedimentación marina ocurrió sobre rocas volcánicas jurásicas del Complejo Marifil. Hacia el sur, la transgresión inicial está representada por los depósitos epiclásticos del Miembro Hansen (&quot;Glauconítico&quot;), apoyados sobre el Grupo Chubut (Cretácico). Así, los depósitos bioclásticos del Miembro Bustamante se interpretan como una evidencia del desarrollo de colonias de invertebrados marinos sustrato-controladas, ya que las rocas volcánicas constituyeron un sustrato más propicio para su colonización por organismos ...

Three-dimensional paleoseismology in strike-slip faults with slip rates less than 1 millimeter per year involves a great methodological challenge. We adapted 3D trenching to track buried channels offset by the Alhama de Murcia seismogenic left-lateral strike-slip fault (SE Iberia). A fault net slip of 0.9 ± 0.1 mm/yr was determined using statistical analysis of piercing lines for one buried channel, whose age is constrained between 15.2 ± 1.1 ka and 21.9-22.3 cal BP. This value is larger and more accurate than the previously published slip rates for this fault. The minimum number of five paleo-earthquakes identified since the deposition of dated layers suggests a maximum average recurrence interval of approximately 5 ka. The combination of both seismic parameters yields a maximum slip per event between 5.3 and 6.3 m. We show that accurately planned trenching strategies and data processing may be key to obtaining robust paleoseismic parameters in low seismicity areas.