Paleoseismologic advances in the Granada basin (Betic Cordilleras, southern Spain)

The Betic Cordilleras in southern Spain have experienced a number of moderate to strong seismic events during the last 2000 years of reported historical earthquakes. These earthquakes are distributed along the southern margin of Spain from Cádiz to Alicante, and offshore in the Alborán sea, reaching the island of Mallorca. Pliocene to Holocene alluvial and colluvial sediments in Neogene basins and adjacent smaller basins in the Betic Cordilleras display a broad range of faults and structures presumably related to coseismic surface deformation. A number of historical earthquakes capable of producing surface ruptures are presented. This study is focussed on reported ruptures and fault scarps, e.g., those of the Christmas event of 1884 (M 6.5-7) near Ventas de Zafarraya, in the southwestern and northeastern parts of the Granada basin. Displaced and buried paleosols and colluvial wedges in the hanging wall suggest multiple fault reactivation. AMS 14C-dating indicates at least three strong events along the Ventas de Zafarraya fault during the last 9 ka. Active faults, and hence seismogenic deformation, are distributed in the Betics, which considerably hinders the calculation of recurrence rates of strong earthquakes along discrete faults. The maximum expectable events for the study area are in the order of M 7.Se tiene registro histórico de que las Cordilleras Béticas, en el sur de España, han experimentado varios eventos sísmicos moderados a fuertes durante los últimos 2000 años. Estos terremotos se distribu yen a lo largo del margen meridional de España, desde Cádiz hasta Alicante, en el mar de Alborán, y continuan hasta la isla de Mallorca. Ciertos depósitos coluviales y aluviales, de edad pliocena a holocena, de las cuencas neógenas de las Cordilleras Béticas presentan un amplio rango de fallas y estructuras relacionadas, presumiblemente, con la deformación cosísmica de la superficie. Se presentan varios terremotos históricos capaces de producir rupturas de la superficie. Este estudio se centra en las rupturas y escarpes de falla descritos en las partes suroccidental y nororiental de la cuenca de Granada, como por ejemplo, los del terremoto de Navidad de 1884 (M 6,5-7) cerca de Ventas de Zafarraya. Paleosuelos enterrados y desplazados, así como cuñas coluviales en el bloque superior sugieren una reactivación múltiple de la falla. Las dataciones realizadas (AMS 1 4C) indican que durante los últimos 9 ka se han producido al menos tres eventos fuertes a lo largo de la falla de Ventas de Zafarraya. Las fallas activas, y por consiguiente la deformación sismogénica, están ampliamente distribuidas en las Béticas, hecho que dificulta considerablemente el cálculo de los períodos de recurrencia de los terremotos fuertes producidos por fallas discretas. Los máximos eventos esperables en la región estudiada son del orden de M 7

Stress transfer and Quaternary faulting in the northern Alpine foreland

Within the SPP Mountain Building Processes in Four Dimensions (MB-4D) we studied postglacial and present seismic rupturing in the northern Alpine Foreland to better understand the impact and forces of mountain building. We started a seismological field experiment to densify the permanent monitoring networks and the AlpArray Seismic Network. The later was also supported as well as its predecessor UNIBRA (Hetényi et al., 2018; Schlömer et al., 2022). Our StressTransfer network consisted of five recording stations in the Upper Rhine Graben, five in the Molasse Basin and five around the Albstadt Shear Zone (Mader et al., 2021a). The latter are still operating due to the increased seismicity during the last years below the western Swabian Alb. We determined local minimum 1-D seismic velocity models to relocate known events in the study regions (Mader et al., 2021b). Waveform cross-correlation was done to detect hitherto unknown events and recover earthquake sequences around the Albstadt Shear Zone (Mader et al., subm.). To determine fault planes and rupture mechanisms we used relative event locations (hypoDD) and FOCMEC for fault plane solutions. For the Albstadt Shear Zone (ASZ), an NNE–SSW striking left-lateral strike-slip rupture zone, we determined a direction of the maximum horizontal stress (SHmax) of 140°–149°. Down to ca. 7–8 km depth, SHmax is bigger than SV (vertical stress); below this depth, SV is the main stress component. Beneath the shallow Hohenzollerngraben (ca. 2-3 km depth), which is nearly perpendicular to the ASZ, we found an NW-SE striking dextral strike-slip fault zone with very weak micro-seismicity in 11-15 km depth (Figure 1). This zone is possibly a reactivated old upper-crustal tectonic structure. At the interception of the ASZ and the NW-SE striking fault zone we observe NNW-SSE striking sinistral strike-slip and normal faulting micro-earthquakes which belong to a heterogeneous deformation zone with complex faulting. In Figure 1 we summarize our current model for the ASZ and its surroundings. The detection of many micro-earthquakes and the related active faults was only possible with the help of the additional temporal recording stations in the region and the studies of a PhD student (S.M.). We thank the DFG for funding our project and the State Earthquake Service Baden-Württemberg in Freiburg for providing data (Az. 4784//18_3303)

Optically controlled grippers for manipulating micron-sized particles

We report the development of a joystick controlled gripper for the real-time manipulation of micron-sized objects, driven using holographic optical tweezers (HOTs). The gripper consists of an arrangement of four silica beads, located in optical traps, which can be positioned and scaled in order to trap an object indirectly. The joystick can be used to grasp, move (lateral or axial), and change the orientation of the target object. The ability to trap objects indirectly allows us to demonstrate the manipulation of a strongly scattering micron-sized metallic particle

Colloidal hydrodynamic coupling in concentric optical vortices

Optical vortex traps created from helical modes of light can drive fluid-borne colloidal particles in circular trajectories. Concentric circulating rings of particles formed by coaxial optical vortices form a microscopic Couette cell, in which the amount of hydrodynamic drag experienced by the spheres depends on the relative sense of the rings' circulation. Tracking the particles' motions makes possible measurements of the hydrodynamic coupling between the circular particle trains and addresses recently proposed hydrodynamic instabilities for collective colloidal motions on optical vortices.Comment: 7 pages, 2 figures, submitted to Europhysics Letter

Evolution of a highly dilatant fault zone in the grabens of Canyonlands National Park, Utah, USA - Integrating fieldwork, ground-penetrating radar and airborne imagery analysis

Abstract. The grabens of Canyonlands National Park are a young and active system of sub-parallel, arcuate grabens, whose evolution is the result of salt movement in the subsurface and a slight regional tilt of the faulted strata. We present results of ground-penetrating radar (GPR) surveys in combination with field observations and analysis of high-resolution airborne imagery. GPR data show intense faulting of the Quaternary sediments at the flat graben floors, implying a more complex fault structure than visible at the surface. Direct measurements of heave and throw at several locations to infer fault dips at depth, combined with observations of primary joint surfaces in the upper 100 m, suggest a highly dilatant fault geometry. Sinkholes observed in the field as well as in airborne imagery give insights in local dilatancy and show where water and sediments are transported underground. Based on correlations of paleosols observed in outcrops and GPR profiles, we argue that either the grabens in Canyonlands National Park are older than previously assumed or that sedimentation rates were much higher in the Pleistocene. This is the final version of the article. It first appeared from Copernicus Publications via http://dx.doi.org/10.5194/se-6-839-2015 The supplement related to this article is available online at http://dx.doi.org/10.5194/se-6-839-2015-supplemen

RMRP (RNA component of mitochondrial RNA processing endoribonuclease)

Review on RMRP (RNA component of mitochondrial RNA processing endoribonuclease), with data on DNA, on the protein encoded, and where the gene is implicated

GEOMETRY OF HOLOCENE TIDAL NOTCHES – SEA LEVEL MARKERS AT PERACHORA PENINSULA, GULF OF CORINTH, GREECE

Tidal notches are a generally accepted sea level indicator that, when different from mean sea level, witness tectonic activity at or near coastlines. However, how to infer related information is controversial since tectonic uplift from a single seismic event is not likely to exceed several decimetres. High resolution laser scanning offers the availability of close-up views on exposures and to detect evidence for multiple sea level indicators in between major emergence. Statistically representative profiles along exposure were analysed in order to prove for already described tidal notches and to highlight similar shapes in consistent geometries along coastal cliffs of Perachora Peninsula.</jats:p

Design strategies for optimizing holographic optical tweezers setups

We provide a detailed account of the construction of a system of holographic optical tweezers. While much information is available on the design, alignment and calibration of other optical trapping configurations, those based on holography are relatively poorly described. Inclusion of a spatial light modulator in the setup gives rise to particular design trade-offs and constraints, and the system benefits from specific optimization strategies, which we discuss.Comment: 16 pages, 15 figure