Mapping and distribution with depth of alteration in rocks is critical in engineering planning because it has a fundamental impact on the geotechnical properties of the materials. Lateral heterogeneity on a weathered rock massif makes boreholes inadequate for its complete characterization. Geophysical methods increase spatial sampling along the study area and can be related to geotechnical parameters, so subsoil conditions can be better understood.In order to determine its geotechnical qualities and variability along two different profiles, we attempt to characterize a granite massif in north‐west Spain by the integration of results from seismic refraction, multichannel analysis of surface waves (MASW) and electrical resistivity tomography methods (ERT). The study area, the so‐called Carlés granite, shows all the weathering grades from sandy soil to fresh rock. A reference borehole where samples were taken and laboratory measurements were made, serves as a direct check for the results of one of the profiles, the other being interpreted without any direct information. This approach has permitted the evaluation of the advantages and limitations of each geophysical method and created an accurate geotechnical model of the massif, correlating physical and geotechnical parameters such as rock quality designation, weathering grade, or standard penetration test.The field seismic velocities have been compared with the ultrasonic measurements at the laboratory, permitting an evaluation of the field and laboratory elastic constants. The trend in the values of these parameters agrees with the field and laboratory test for the shallow parts of the massif. However, unrealistic elastic constants have been obtained for fresh rock based on the results of the field experiments. This is related to an apparent underestimation of the velocity of seismic S‐waves for the deepest layers. This fact suggests that the methodology followed throughout this work is able to provide a full geotechnical model of an altered rock massif for the first tens of metres, discriminating between different weathered levels. It is also useful and reliable when inferring elastic constants for depths of up to 20 m. However, its validity becomes doubtful with depth, so care must be taken when calculating elastic moduli and trying to extrapolate directly to a rock massif.

A hybrid zone betweenChorthippus parallelus parallelus and Chorthippus parallelus erythropus (Orthoptera: Acrididae) : chromosomal differentiation. Genome, 30: 656 -663. Two subspecies of the meadow grasshopper Chorthippus parallelus form narrow hybrid zones in the Pyrenees. We studied the patterns of chromosome divergence to evaluate their possible role in the maintenance of such hybrid zones under natural conditions. The two subspecies share some common features such as identical chromosome number, similar basic chromosome form, and the GC-rich nature of all the heterochromatic DNA. Similar positions for the nucleolar organizer region (NOR) in two pairs of autosomes were also observed. The main difference was the presence of an active NOR in the X chromosome in Cp. parallelus that was absent from Cp. erythropus. The pattern of banding by C-banding, acridine orange, and chromomycin A3 abo showed the subspecific characteristics on this chromosome. The presence or absence of an active NOR on the X chromosome was used to analyse the hybrid zones in two different transects of the Pyrenees, and clear clines of X NOR frequencies were observed passing from Cp. parallelus to Cp. erythropus. Some meiotic abnormalities were found in individuals from the hybrid zones with the subsequent production of abnormal sperm. Differences in genetic activity involving the sexual chromosome and the male sterility found in F1 hybrids produced in laboratory crosses are discussed as an example of Haldane's Rule. et HEWITT, G. M. 1988 . A hybrid zone betweenChorthippus parallelus parallelus and Chorthippus parallelus erythropus (Orthoptera: Acrididae) : chromosomal differentiation. Genome, 30 : 656 -663. Dans les PyrCnCes, deux sous-espkces de la sauterelle des pds, Chorthippus parallelus, foment des zones hybrides Ctroites. Leurs profils de divergence chromosomique ont Ct C CtudiCs, en vue d'kvaluer leur r6le possible dans le maintien de telles zones hybrides, sous les conditions naturelles. Les deux sous-espkces ont des traits communs, comme un nombre identique de chromosomes, une forme chromosomique de base similaire et une nature riche en GC pour tous les ADN hCtCrochromatiques. Egalement, des positions similaires pour les dgions organisatrices de nuclColes (RON = NOR) chez deux paires d'autosomes ont Ct C observCes. La principale diffkrence A i d e dans la prksence d'une RON active chez le chromosome X de Cp. parallelus, qui ne se retrouve pas chez le Cp. erythropus. Les profils de bandes, par dvClation des bandes C, par l'acridine orange et la chromomycine A3, dCmontrent Cgalement des caractkres subspCcifiques chez ce chromosome. La prksence ou l'absence d'une RON active sur le chromosome X ont Ct C utilisCes pour analyser les zones hybrides dans deux transects diffkrents des PydnCes; des clivages nets de frkquences des RONs chez les chromosomes X ont Ct C observCs, en passant du Cp. parallelus au Cp. erythropus. Certaines anomalies mCiotiques ont Ct C notCes chez des individus des zones hybrides, avec production subsCquente de sper...

The distribution of seismicity at the western end of the Cantabrian mountain range (NW Iberia), reflecting current crustal dynamics, is investigated integrating seismically active structures, long-term structures, and the topographic features at the surface. The thickness of the seismogenic zone within the continental crust is established in 20 km. Two crustal domains can be distinguished in the study area in terms of the seismicity pattern, the style of Alpine structures and the relief. The presence of crustal fluids arises as a very likely contributing factor to the excessive thickness of the seismogenic zone in the study area. More importantly, a switch in tectonic style at the transition between crustal domains in coincidence with the lateral termination of orogenic frontal thrusts is envisaged as involving sufficient stress heterogeneity and amplification to explain the current concentration and characteristic pattern of historical seismicity in the region. Overall, the distribution of seismicity in the crust is sensitive to the type and style of crustal structures.

No abstract

Intraplate seismicity in NW Spain, an otherwise stable continental area, is dominated by low magnitude events and occurs both in swarms or dispersed along faults. A detailed study of one of the most active fault segments, the Ventaniella Fault, has produced an accurate image of foci distribution and revealed new insights on the origin of this lingering activity. The improved location of earthquakes by a temporary seismic network has allowed to better constrain the geometry of the seismogenic segments of the fault at depth. Between 2015 and 2017, a portable seismic array of 10 seismographs recorded 45 low magnitude earthquakes (<2) at depths between 9-18 km. These hypocenters define a tubular trend plunging to the northwest. The linear seismicity pattern is interpreted as the result of the intersection at depth of two main fault planes: a NW-SE fault reactivated in the Alpine Orogeny and the frontal thrust of the Cantabrian Mountains running E-W. The clustering of earthquakes along this particular line of intersecting faults coincides spatially with the presence at depth of an important lateral gradient in crustal thickness, related to the termination of the crustal root beneath the Cantabrian Mountains.The mechanical constraints in the continental crust imposed by the arrangement of crustal scale faults and the gradient in crustal thickness may have reactivated seismically old faults in a context of a stable continental area.