Neoteetonics of the eastern border of the Madrid basin

[Abstract] An analysis ofthe neotectonic activity and the current stress state of the eastern border of Madrid Basin has been carried ont using structural-methods (fault population analysis), as well as seismological methods. Two stress tensors have been established: - Tensor 1: with a N1500E shortening trend, characterized mainly by strikeslip faults. This tensor corresponds to the «Guadarrama» stress field (Capote et al., 1990), wihch causes the Central System structure; dated middle Aragonian -lower Pleistocene in the eastern border ofMadrid Basin (Muñoz Martín, 1993). - Tensor 2: dated post-Iower Pleistocene, with a N150° E extension trend, characterized basically by normal faults. Actual stress tensor deduced focal mechanisms by the seismological method is compatible with the paleostress field deduced for the middle-Iower Pleistocene (tensor 2)

Seismogenic zoning based on the geothermal gradient, strenght and depth of the fragile-ductile transition in the upper crust. Methodological approach for seismic hazard calculations in southeast Spain

In this work we present a methodological approach to define seismogenic zones for seismic hazard analysis based on the relationships which can be drawn from the geothermal gradient, total strength of the upper crust and the depth of the fragile-ductile transition, and their relation with the mean focal depth and a parameter hereby defined: Seismic Density Index (number of events per km3 x 1000). A revision of the deep geophysical data available in SE Spain has led to the definition of 6 distinctive crustal blocks. Two main types of crustal blocks are identified: hot-and-weak and cold-and-strong. Hot-and-weak blocks show consistently higher geothermal gradients, lower strengths and shallower fragile-ductile depths than coldand- strong blocks. Furthermore hot-and-weak blocks show higher seismic density indexes and shallower mean focal depths. However, two blocks biased from this relationship and so are called anomalous. According to these results four seismogenic zones can be defined in SE Spain. The a and b parameters of the Gutenberg-Richter law of each zone are consistent with the thermal and strength properties of the blocks. Zones based on the hot-and-weak blocks show higher a and b values than the cold-and-strong ones, while the anomalous blocks show values in between these extreme

Seismic effects in archaeological sites: Archaeoseismological cataloguing and quantification

The analysis of the damage caused by seismic events in archaeological sites provides significant information about ancient and historic earthquakes that can improve seismic hazard analysis. In this paper a methodological analysis to quantify the deformation of structural damage recorded in archaeological sites is proposed. This methodology focuses on the establishment of the seismic/non-seismic origin of the observed damage and consists of three phases: (a) identification and inventory of damage; (b) quantification of deformation; and (c) incorporation of the results to seismic catalogues. The first phase is the inventory and mapping of the damage according with the classification of archaeological effects of earthquakes (EAEs). The second phase is to quantify the deformation of damage by setting different parameters such as the direction of maximum horizontal strain (ey). This analysis is performed at different levels: for each of the recorded EAEs, for all the records of a particular category of EAEs, and finally for the complete archaeological site including all the categories of EAEs. The homogeneity of the results (damage orientation) allows us to establish the seismic origin of deformations. This methodology has been developed in the Roman site of Baelo Claudia (Cádiz, Spain) and has been applied to different historical earthquakes in the Iberian Peninsula. To calibrate the method, analyses on oriented damage were carried out immediately after the recent instrumental earthquakes of Lorca 2011 (5.1 Mw, Spain) and Emilia Romagna 2012 (5.9 Mw; Italy).The analysis of the damage caused by seismic events in archaeological sites provides significant information about ancient and historic earthquakes that can improve seismic hazard analysis. In this paper a methodological analysis to quantify the deformation of structural damage recorded in archaeological sites is proposed. This methodology focuses on the establishment of the seismic / non-seismic origin of the observed damage and consists of three phases: (a) identification and inventory of damage; (b) quantification of deformation; and (c) incorporation of the results to seismic catalogues. The first phase is the inventory and mapping of the damage according with the classification of archaeological effects of earthquakes (EAEs). The second phase is to quantify the deformation of damage by setting different parameters such as the direction of maximum horizontal strain (ey). This analysis is performed at different levels: for each of the recorded EAEs, for all the records of a particular category of EAEs, and finally for the complete archaeological site including all the categories of EAEs. The homogeneity of the results (damage orientation) allows us to establish the seismic origin of deformations. This methodology has been developed in the Roman site of Baelo Claudia (Cádiz, Spain) and has been applied to different historical earthquakes in the Iberian Peninsula. To calibrate the method, analyses on oriented damage were carried out immediately after the recent instrumental earthquakes of Lorca 2011 (5.1 Mw, Spain) and Emilia Romagna 2012 (5.9 Mw; Italy).Este trabajo ha sido financiado por los proyectos CGL2015-67169-P (QTECTSPAIN, USAL) y CATESI-07 (IGME). Es una contribución al INQUA TERPRO Project 1299 y a los grupos de trabajo QTECT-AEQUA y GQMAEQU

Identification of the direct regulon of NtcA during early acclimation to nitrogen starvation in the cyanobacterium Synechocystis sp. PCC 6803

In cyanobacteria, nitrogen homeostasis is maintained by an intricate regulatory network around transcription factor NtcA. Although mechanisms controlling NtcA activity appear to be well understood, its regulon remains poorly defined. To determine the NtcA regulon during the early stages of nitrogen starvation for the model cyanobacterium Synechocystis sp. PCC 6803, we performed chromatin immunoprecipitation, followed by sequencing (ChIP-seq), in parallel with transcriptome analysis (RNA-seq). Through combining these methods, we determined 51 genes activated and 28 repressed directly by NtcA. In addition to genes associated with nitrogen and carbon metabolism, a considerable number of genes without current functional annotation were among direct targets providing a rich reservoir for further studies. The NtcA regulon also included eight non-coding RNAs, of which Ncr1071, Syr6 and NsiR7 were experimentally validated, and their putative targets were computationally predicted. Surprisingly, we found substantial NtcA binding associated with delayed expression changes indicating that NtcA can reside in a poised state controlled by other factors. Indeed, a role of PipX as modulating factor in nitrogen regulation was confirmed for selected NtcA-targets. We suggest that the indicated poised state of NtcA enables a more differentiated response to nitrogen limitation and can be advantageous in native habitats of Synechocystis.Ministerio de Economia y Competitividad (MINECO) [BFU2013-41712, BIO2016-75634]; Junta de Andalucia-European Regional Funds (FEDER) [BIO-284, P12-BIO-1119]; FCT (Fundacao para a Ciencia e a Tecnologia) [PTDC/BIA-MIC/4418/2012, IF/00881/2013, UID/BIM/04773/2013-CBMR, UID/Multi/04326/2013-CCMAR]; School of Biomedical & Healthcare Sciences, Plymouth University Peninsula Schools of Medicine and Dentistryinfo:eu-repo/semantics/publishedVersio

Pulverized quartz clasts in gouge of the Alhama de Murcia fault (Spain): evidence for coseismic clast pulverization in a matrix deformed by frictional sliding

The fault gouge of the Alhama de Murcia fault (southeast Spain) shows a texture that resembles a mylonite, including a prominent foliation, S-C fabric, and isoclinal folds. It also embeds a large number of isolated pulverized quartz clasts (PQCs). Structural analysis indicates that the gouge fabric was mainly developed by slow frictional sliding along phyllosili- cate-lined Riedel shear bands during continued shearing. In contrast, the PQCs show tensile fracture network features that are typically reported in seismically pulverized rocks found along seismogenic faults. This suggests that quartz-clast pulverization was due to a transient dilatational mechanism rather than shearing. We propose that the PQCs are the result of a rapid confined stress drop related to transient tensile stresses during coseismic ruptures that interrupt creep faulting along the gouge zone. The present study suggests that there is probably a large amount of evidence for paleoseismicity in fault rocks that is currently overlookedThis research was supported by the Spanish Ministry of Economy and Competitiveness under the INTERGEO (CGL2013–47412-C2–1-P) and QUAKESTEP (CGL2017–83931-C3–1-P) project

Alpine structure and evolution of central Spain

Dirección General de Investigación Científica y Técnica; PB91-039

Evidencias paleosísmicas y geomorfológicas de actividad tectónica reciente de la Falla de Pozohondo (Cordillera Bética, SE de España)

Instrumental and historical seismicity in the Albacete province (External Prebetic Zone) has been scarcely recorded. However, major strike-slip faults showing NW-SE trending provide geomorphologic and paleoseismic evidence of recent tectonic activity (Late Pleistocene to Present). Moreover, these faults are consistently well oriented under the present stress tensor and therefore, they can trigger earthquakes of magnitude greater than M6, according to the lengths of surface ruptures and active segments recognized in fieldwork. Present landscape nearby the village of Hellin (SE of Albacete) is determined by the recent activity of the Pozohondo Fault (FPH), a NW-SE right-lateral fault with 90 km in length. In this study, we have calculated the Late Quaternary tectonic sliprate of the FPH from geomorphological, sedimentological, archaeoseimological, and paleoseismological approaches. All of these data suggest that the FPH runs with a minimum slip-rate of 0.1 mm/yr during the last 100 kyrs (Upper Pleistocene-Holocene). In addition, we have recognized the last two major paleoearthquakes associated to this fault. Magnitudes of these paleoearthquakes were gretarer than M6 and their recurrence intervals ranged from 6600 to 8600 yrs for the seismic cycle of FPH. The last earthquake was dated between the 1st and 6th centuries, though two earthquakes could be interpreted in this wide time interval, one at the FPH and other from a far field source. Results obtained here, suggest an increasing of the tectonic activity of the Pozohondo Fault during the last 10,000 yrs.A pesar de la escasa sismicidad instrumental e histórica en el Prebético Externo, que comprende la provincia de Albacete, existen tres grandes fallas con evidencias de actividad reciente y cuya orientación es compatible con el campo de esfuerzos activo. Estas fallas consisten en desgarres dextrorsos de orientación NO-SE cuya longitud de traza sobrepasa los 50 km. Este trabajo se centra en el análisis del segmento Tobarra-Cordovilla de la Falla de Pozohondo (FPH) (90 km de longitud), mediante estudios paleosísmicos, geomorfológicos, sedimentológicos e incluso arqueosísmicos. De todos estos análisis es posible afirmar que dicha falla (FPH) presenta una tasa de actividad cuaternaria superior a 0,1 mm/año durante los últimos 100 ka (Pleistoceno Superior-Holoceno). Además, se han descrito los últimos dos paleoterremotos asociados a este segmento con una tasa de recurrencia para magnitudes superior a M6 de 6600-8600 años, habiendo tenido lugar el último evento entre los siglos I y VI. Sin embargo, los datos no permiten fijar de forma más precisa dicho evento, e incluso es posible que hayan tenido lugar dos eventos diferenciados durante este periodo, uno relacionado con la FPH y el otro de origen de campo lejano. En cualquier caso, se evidencia un suave incremento en la actividad tectónica en la zona durante los últimos 10.000 años

Speleoseismology and palaeoseismicity of Benis Cave (Murcia, SE Spain): coseismic effects of the 1999 Mula earthquake (mb 4.8)

This work describes the coseismic ceiling block collapse within Benis Cave (−213 m; Murcia, SE Spain), associated with the 1999 Mula earthquake (mb=4.8, MSK VII). The collapse occurred at −156 m into the Earthquake Hall, and as a consequence one small gallery became blind. We studied the geology, topography and active tectonic structures relevant to the cave. In addition, we carried out a seismotectonic analysis of the focal mechanism solutions, and also a fault population analysis on slickensides measured in fault planes in the cave. The stress and strain regime is interpreted as being congruent with the palaeoseismic evidence, and agrees with the fault kinematics established for cave galleries developed within fault planes and growth anomalies of coral flowstone. Our analysis suggests that one active segment (NNE–SSW) determined the morphology and topography of the Benis Cave, where strong to moderate palaeoearthquakes (6≤M≤7) took place. As a consequence of this intense seismic activity a small gallery collapsed. A new palaeoseismic structure, or seismothem, has been recognized, namely the effect of palaeoearthquakes affecting the pattern of development of the spatial coral flowstone distribution located at the bottom of the cave

Paleogeografía sísmica de zonas costeras en la Península Ibérica: su impacto en el análisis de terremotos antiguos e históricos en España

This paper presents three examples of ancient earthquakes occurring in coastal areas of the S and SE of the Iberian Peninsula (218 BC, AD 40-60 and AD 1048) with the aim of illustrating the use of geological and archaeological data in their macroseismic characterization. Historical information for ancient earthquakes that occurred in Spain prior to the 10th century is scarce or non-existent. This paper shows that the current state of knowledge on palaeoseismology and archaeoseismology on these ancient events clearly exceeds the existing historical information allowing the increase of macroseismic information points by using the ESI-07 scale (Environmental Seismic Intensity). Consequently, the geologic analyses of ancient earthquakes contribute to their understanding and parametric evaluations, and improve further advances in seismic hazard assessments. The most significant issue outlined in the present paper is the analysis of the ancient palaeogeography of the affected areas. The studied examples analysed were located in open estuarine areas that have been filled by fluvial sediments or anthropogenic fills over time. The effects of the 218 BC earthquake-tsunami event in the Gulf of Cadiz are analysed in estuarine areas, and especially in the ancient Roman Lagus Ligustinus (Guadalquivir Depression marshes); the effects of the earthquake in AD 40-60 is analysed in the old Roman city of Baelo Claudia located in the Bolonia Bay (Strait of Gibraltar); and the effects of the earthquake of AD 1048on the ancient Sinus Ilicitanus (Bajo Segura Depression) during Muslim times. Descriptions from Roman and Arabic geographers are cross-checked with existing palaeogeographic models based on geological data. This type of analysis results in ancient macroseismic scenarios for the interpretation of theoretical distributions of intensities and environmental effects supporting the concept of “seismic palaeogeography” proposed in this paperEl presente trabajo recoge tres ejemplos de terremotos antiguos (218 AC, 40-60 AD y 1048 AD) ocurridos en zonas litorales del S y SO de la Península Ibérica con la intención de ilustrar el uso de datos geológicos y ar¬queológicos en la caracterización macrosísmica de los mismos. En la mayor parte de los sísmos ocurridos con anterioridad al siglo X d.C. la información documental histórica que se posee es muy escasa o inexistente. El presente trabajo muestra que el actual estado de conocimiento en paleosismología y arqueosismologia sobre este tipo de terremotos sobrepasa con creces la información documental histórica, permitiendo la multiplica¬ción de los puntos de información macrosísmica mediante el uso de la escala ESI-07 (Environmental Seismic Intensity). Consecuentemente, el análisis geológico de los terremotos antiguos mejora su conocimiento y análisis paramétrico, permitiendo avanzar la evaluación de la peligrosidad sísmica de las zonas afectadas. El aspecto que se pone de especial relieve en este trabajo es el análisis de la paleogeografía existente en la antigüedad, ya que todas las zonas (afectadas) analizadas en este trabajo corresponden a zonas estuarinas abiertas que se han ido rellenado por aportes fluviales o de forma artificial con el tiempo. Se analizan los efectos del terremoto de 218 AC en las zonas estuarinas del Golfo de Cádiz y muy especialmente en el antiguo Lacus Ligustinus (marismas del Guadalquivir) durante época romana; los efectos del terremoto de 40-60 AD en la antigua Bahía de Baelo Claudia (Estrecho de Gibraltar); y los efectos del terremoto de 1048 AD en el antiguo Sinus ilicitanus (Depresión del Bajo Segura) durante época musulmana. Se han cotejado descripciones de geógrafos romanos y árabes con modelos basados en datos geológicos. Este tipo de análisis ha permitido generar antiguos escenarios macrosísmicos basados en la paleogeografía y reinterpretar las distribuciones teóricas de intensidades y los efectos ambientales de los terremotos estudiados que es a lo que se refiere el concepto de “paleogeografía sísmica” propuesto en este trabajoThis work has been funded by the Spanish-FEDER research projects CGL2012-37281 C02.01 (QTECTBETICA-USAL), CGL2012-33430 (CSIC) and CGL2013-42847-R (UNED