Ancient earthquakes in the Roman city of Baelo Claudia (Cádiz, South of Spain): Fifteen years of archaeosimology research

[ES] El presente trabajo ilustra el estado del conocimiento sobre arqueosismología en la antigua ciudad romana de Baelo Claudia (Tarifa, Cádiz) tras casi quince años de investigaciones. Esta antigua ciudad romana se vio afectada por dos importantes terremotos en los años 40–60 AD y 260–290 AD. El primero de ellos afectó en mayor grado a la parte baja (costera) de la ciudad provocando importantes cambios urbanísticos y arquitectónicos (monumentalización) en respuesta a las labores de reconstrucción. El segundo de ellos provocó una mayor destrucción, cuya ruina progresiva desembocó en el abandono definitivo de la ciudad en el 365–390 AD. Se catalogan, cartografían y describen la mayor parte de los Efectos Arqueológicos de los Terremotos (EAEs) del sector monumental de la ciudad, que testifican los efectos producidos por el terremoto ocurrido en el 260–90 AD. La cartografía de daños (EAEs) muestra la distribución y orientación de los daños en la zona baja de la ciudad, así como la ocurrencia de otros procesos cosísmicos, como deslizamientos y pequeños tsunamis. El análisis estructural del conjunto de daños orientados indica que la dirección de movimiento del terreno se produjo en una dirección dominante del SO al NE. Los análisis geoarqueológicos, así como importantes anomalías constructivas y funerarias, sugieren la intervención de tsunamis de escaso poder de penetración durante los dos terremotos, apuntando a la existencia de una fuente sísmica submarina común al SSO de la ciudad. Se han identificado diferentes fallas normales de dirección N-S en la zona de la Bahía de Bolonia, algunas de las cuales se prolongan hacia el interior del mar en la zona SSO de Baelo Claudia. Estas fallas presentan claras evidencias de actividad Cuaternaria y podrían considerarse como las fuentes sísmicas más probables para los dos antiguos terremotos que afectaron a la ciudad en época romana.[EN] This work illustrates the state of the art on archaeoseismology of the ancient Roman city of Baelo Claudia (Tarifa, Cádiz) after nearly fifteen years of research. This ancient Roman site was affected by two earthquakes in the years AD 40-60 and AD 260-290 which promoted important urban and architectural changes and eventually the destruction and further abandonment of the city in AD 365-390. Earthquake Archaeoseismological Effects (EAEs) are catalogued, described and mapped in the entire monumental sector of the city mainly witnessing the last earthquake which occurred in AD 260-290. Mapping of oriented EAEs illustrate damage distribution all over the lower sector of the city, as well as the occurrence of suspect coseismic landslide and tsunami events. The structural analysis of oriented EAEs throughout the entire mapped sector suggests that the intervening ground motion was preferentially oriented in a SW to NE direction. The geoarchaeological analysis and some relevant archaeological anomalies, strongly suggest the occurrence of coeval tsunami events during both ancient earthquakes, pointing to the occurrence of an offshore seismic source SSW of the city. Several N-S normal faults have been identified around the Bolonia Bay area and some of them continue offshore SSW of Baelo Claudia. These faults with clear Quaternary activity can be considered as the more probable seismic sources for the events affecting the ancient Roman site and they are consistent with the mapped damage orientation displayed by the structural analysis of EAEs within the old Roman cityEste trabajo ha sido financiado por sucesivos proyectos de investigación en la zona desde el año 2001 y en la actualidad por los Proyectos de Investigación CGL2015-67169-P (USAL: QTECTSPAIN), CGL2012-37281-C02.01 (USAL: QTECTBÉTICA) y CGL2012-33430 (MNCN, CSIC).Peer Reviewe

Pattern of sedimentary infilling of fossil mammal traps formed in pseudokarst at Cerro de los Batallones, Madrid Basin, central Spain.

Fossil mammal sites of late Miocene age (ca 9 Ma) occur in hourglassshaped, non-interconnected cavities up to 15 m deep, hosted in mudstone (mostly sepiolite), chert and carbonate bedrock in Cerro de los Batallones. This paper provides a model for the sedimentary infilling of the cavities, which functioned as traps for vertebrate faunas and contain one of the richest and best preserved Neogene mammal assemblages of the Iberian Peninsula. Generation of the mammal-bearing cavities started with the solution of underlying evaporites, which resulted in fissures that were subsequently enlarged by subsurface piping, a process rarely preserved in the ancient sedimentary record. The system of subterranean cavities evolved into a pseudokarst landscape, resulting in doline-like shafts reaching the ancient land surface. The sedimentary infilling of the cavities comprises both clastic and carbonate lithofacies that were investigated by outcrop observation, standard and scanning electron microscope petrography, mineralogical analysis, and stable isotope geochemistry. Gravel and breccia talus deposits, clast and mud-supported gravel, pebbly sandstone and mudstone are common detrital infill deposits mostly derived by overflow erosion of bedrock. The deposits containing the mammal bones are marls, and occur both in subsurface cavities and doline-like depressions. In the underground cavities, marlstone was mainly of clastic origin and accumulated in ponds scattered over the floor of the cavity. In contrast, marlstone deposits in the surface dolines formed mostly as a result of biochemical carbonate deposition in small shallow lakes subjected to fluctuation of the water level. The d18O and d13C carbonate values indicate different origins for the two kinds of marls. During the final phases of pipe infill the doline marlstone sealed the mammal sites, usually off-lapping the adjacent bedrock

Geomorphological setting and main technological features of new Middle and Upper Pleistocene sites in the Lower Manzanares River Valley (Madrid, Spain)

Las intervenciones arqueológicas llevadas a cabo durante los años 1996 en Tafesa, 2005 en el yacimiento Hospital 12 de Octubre y 2006 en la desembocadura del arroyo Butarque (Villaverde-Barrio de Butarque) situados al sur de la ciudad de Madrid (España), han aportado nuevos conjuntos líticos contextualizados estratigráficamente en los depósitos fluviales pleistocenos correspondientes al tramo inferior del valle del río Manzanares. Los yacimientos arqueológicos analizados se sitúan geomorfológicamente en la denominada “Terraza Compleja del Manzanares” (TCMZ), la cual constituye un nivel fluvial engrosado (20-15 m de potencia) situado entre +22-16 m sobre el cauce actual del río, a lo largo de su margen derecha. Este nivel fluvial ha sido tradicionalmente considerado de edad Pleistoceno medio en base a la industria achelense y complejos faunísticos encontrados en sus niveles inferiores. Ciertamente, Tafesa es un yacimiento situado en la parte inferior-media de la terraza de +22 m con industria achelense y fauna de Pleistoceno medio. Por el contrario, los niveles superiores de esta misma terraza en los sectores del 12 de Octubre y Villaverde-Butarque se encuentran asociados a industrias del Paleolítico inferior y medio ya pertenecientes al Pleistoceno superior, como sugieren el conjunto de dataciones OSL y TL existentes para la zona. Los datos analizados en este trabajo indican que el desarrollo de este nivel de terraza engrosado comienza durante la parte final de Pleistoceno medio y abarca todo el Estadio Isotópico OIS 5, ya dentro del Pleistoceno superiorThe archaeological works developed during the years 1996 in the site of Tafesa, 2005 in the 12 de Octubre Metro Station site and 2006 in the confluence of the Butarque Stream (Villaverde-Barrio de Butarque site) located south of the Madrid City (Spain), have provided new lithic assemblages. These assemblages have been stratigraphically contextualized in the Pleistocene deposits of the Lower Manzanares river valley within the so-called “Manzanares Complex Terrace” (TCMZ). This fluvial terrace constitutes an anomalous thickened (20-15m) deposit at +22-16m above the present river thalweg mainly developed along the right (southern) valley margin. This fluvial level has been traditionally considered of middle Pleistocene age on the basis of the acheulian lithics and faunal assemblages typically located within its lower stratigraphic layers. Certainly, the Tafesa is a fluvial terrace site at +22 m with acheulian industry and middle Pleistocene faunal remains at its lower sedimentary sequence. However, the upper sedimentary levels of this same terrace in the 12 de Octubre y Villaverde-Butarque sites throw lithic assemblages of the lower and upper Paleolithic belonging to upper Pleistocene, as suggested by the available set of TL and OSL dates for the zone. The analyses developed in this study indicate that the development of this thickened fluvial terrace started during the end of the middle Pleistocene, but also comprise the whole Oxygen Isotopic Stage OIS 5 during the upper Pleistocene

Fan-surface dynamics and biogenic calcrete development: Interactions during ultimate phases of fan evolution in the semiarid SE Spain (Murcia)

Pleistocene alluvial fan surfaces of the Campo de Cartagena–Mar Menor Basin, Murcia, SE Spain. are capped by thick mature calcretes. Calcrete profiles consist mainly of six different horizons: prismatic, chalky, nodular, massive, laminar and coated-gravels. Petrographic study of the calcretes has shown the occurrence of features such as alveolar septal structures, calcified filaments, coated grains, spherulites, calcified root cells and calcispheres that indicate the biogenic origin of the calcretes, mainly induced by plant root related microbial activity. The calcretes studied were formed initially in the soil and represented the K horizon. Development of the calcrete profiles took place in six main stages and was driven by multiple phases of soil formation, erosion and reworking. The relationships between these processes caused the formation of different calcrete profiles in proximal and distal fan areas. In the distal areas, which are controlled by limited distal fan aggradation, episodic sediment input, buried previously developed calcretes and generated new space for calcrete growth by plants growing in the overlying unconsolidated materials. This allowed the renewal of calcrete formation and it led to the development of complex composite profiles which are thicker than in proximal areas, where surface stabilisation andror dissection enabled calcrete reworking and brecciation. These processes of erosion, sedimentation, reworking and renewed calcrete formation initiated by vegetation were repeated through time. They explain the complex macro- and microstructures of these calcretes and indicate that calcrete development, even reaching mature stages, can start before the fan surface is completely abandoned, but it requires episodic sedimentation. Eventually, distal fan aggradation and continuous calcrete development throughout the entire fan surface, led to the ultimate fan surface induration, controlling subsequent landscape evolution. So, fan surface calcretes cannot be envisaged as simple top-surface carbonate accumulations, but as complex feedback systems in which pedogenic, biogenic and sedimentary processes interact in response to the evolving fan-surface dynamics during the terminal phases of fan development in semiarid environments. q1998 Elsevier Science B.V. All rights reserved

Modelos Analógicos en Ingeniería. La “pecera” multiusos

Memoria ID12-0041. Ayudas de la Universidad de Salamanca para la innovación docente, curso 2012-2013

Geology and Archaeology of the late 4th century CE Earthquake-Tsunami event that struck the ancient roman city of Baelo Claudia (Cádiz, South Spain)

El presente trabajo resume el conjunto de nuevas investigaciones geológicas y arqueológicas que certifican la ocurrencia de un potente evento terremoto-tsunami que devastó la antigua ciudad romana de Baelo Claudia (Estrecho de Gibraltar) en la segunda mitad del siglo IV d.C. Aparte de las importantes de formaciones cosísmicas documentadas en forma de deformaciones en los restos arquitectónicos (EAEs) el presente estudio se centra en los efectos y registro sedimentario del tsunami que acompaño al terremoto. El análisis de los depósitos de tsunami en sondeos y afloramientos de la parte baja de la ciudad indican que este alcanzó una altura mínima de + 8 m por encima del nivel del mar y que penetró al menos 250 m hacia el interior alcanzando la base de los templos en la zona del Foro. Sin embargo, en los pequeños arroyos que se encuentran en la zona y en la antigua laguna litoral oriental la inundación pudo penetrar hasta algo más de un kilómetro. La capa del tsunami ha sido bien documentada dentro y fuera de la ciudad en trabajos anteriores y se encuentra bien. La tsunamita es un depósito arenoso cohesivo oscuro (de 28 a 52 cm de grosor) que contiene fragmentos de cerámica, huesos de pescado y de animales, cristalería, ladrillos y grandes bloques de mampostería y tambores de columnas. La capa también contiene conjuntos microfaunísticos con una mezcla de foraminíferos bentónicos y planctónicos, así como gasterópodos lagunares de agua salobre y numerosos restos de conchas y foraminíferos rotos reelaborados. Los datos presentados en este trabajo indican que la capa del paleotsunami se compone principalmente de arenas finas-medias bien redondeadas procedentes de la reelaboración de depósitos eólicos y de las antiguas playas y barras litorales que en época romana cerraban la antigua bahía. Interpretamos que la mayoría de los depósitos de tsunami son depósitos de backwash (retroceso de la ola) que quedaron atrapados entre las ruinas de la ciudad y especialmente a lo largo del Decumano Máximo, Termas marítimas y Mausoleo de Iunia Rufina en la necrópolis oriental de la ciudad. Los hallazgos arqueológicos en este monumento derribado por el terremoto y posterior tsunami permiten establecer la edad de este suceso entre los años 350 - 390 AD.This paper summarizes the set of new geological and archaeological studies that certify the occurrence of a powerful earthquake-tsunami event that devastated the ancient Roman city of Baelo Claudia (Strait of Gibral tar) in the second half of the 4th century AD. Apart from the important coseismic deformations documented in the in the architectural remains (EAEs), the present study focuses on the effects and sedimentary record of the subsequent tsunami. Analysis of tsunami deposits in drill cores and outcrops along the lower part of the city indicate that the tsunami reached a minimum height of + 8m above sea level and penetrated at least 250 m inland reaching the base of the temples above the Forum area. However, in the small creeks around the area and in the ancient eastern littoral lagoon, flooding could have penetrated up to about one kilometre. The tsunami layer is a dark cohesive sandy deposit (28 to 52 cm thick) containing fragments of pottery, fish and animal bones, glassware, bricks and large boulders of masonry blocks and column drums. The layer also contains microfaunal assemblages with a mixture of benthic and planktonic foraminifera as well as lagoonal brackish-water gastropods and numerous shell debris and broken reworked foraminifera. Data presented in this work indicate that the tsunami layer is mainly composed of well-rounded fine-medium sands originating from the reworking of aeolian and littoral beach deposits of the old roman spit-bar enclosing the ancient embayment. We interpret most of the tsunami layer as backwash deposits trapped within the ruins of the city after the earthquake destruction, as testified by recent excavations along de decumanus maximum, Termas Marítimas and the funerary mausoleum of Iunia Rufina in the eastern necropolis. The archaeological findings in this funerary monument toppled by the earthquake and the subsequent tsunami allow to establish the age of this event between 350 - 390 AD.Esta investigación forma parte del Proyecto de Investigación Español I+D+i PID2021-123510OB-I00 (QTECIBERIA-USAL) financiado por el MICIN AEI/10.13039/501100011033/ y por el Instituto de Neotectónica y Riesgos Naturales de la Universidad RTWH Aachen (Alemania). Esta es una contribución del Grupo de Trabajo QTECT-AEQUA

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

El pleistoceno medio y superior en la secuencia ceneral de las terrazas del Guadalquivir (sgtg): nuevas dataciones por luminiscencia de la t12 y t13 en la Rinconada (SW de España)

This work includes the luminescence dating (quartz-OSL, pIRIR on K-feldespar and TL) of the T12 and T13 terraces of the Guadalquivir River near La Rinconada (Seville). Lithic Achelense industry is located from the basal USLC-1 unit of T12, together with remains of macromammal fauna. The results obtained of the analysis of the T12 terrace in “Sando-La Cabaña” show that the age or the unit lower in the terrace is older than 240 ka, probably, corresponding to MIS12-MIS11 or MIS10-MIS9.The upper part of the alluvial formation of the T13 presents an absolute age (quartz-OSL) of ca.75 ka (MIS5a)

Landscape evolution and geodynamic controls in the Gulf of Cadiz (Huelva coast, SW Spain) during the Late Quaternary

The coastal evolution of the El Abalario area (Huelva, southern Spain) during the Late Pleistocene and Holocene is reinterpreted after a refinement of the available geochronology by means of optically stimulated luminescence (OSL) dating. New data come from the analysis of soft sediment deformation, palaeosols, geomorphological mapping, and published seismic surveys on the onshore and offshore Gulf of Cadiz. The present structure of El Abalario dome resulted from the complex interaction of littoral-catchment processes and sea-level changes upon an emergent coastal plain, conditioned by the upwarping of the underlying Pliocene - Pleistocene prograding deltaic sequence. Upwarping is probably related to escape of over-pressurized fluids, accompanied by dewatering, prior to (?) and during OIS (Oxygen Isotopic Stage) 5. Continued upwarping produced the large NW - SE gravitational fault of Torre del Loro (TLF) in the southwestern flank of the dome, roughly parallel to the present coastline during OIS 5 - OIS 4. The resulting escarpment favoured the accumulation of aeolian sand dunes (units U1, U2, and U3) from OIS 5 to early OIS 1. Unit U1 (OIS 5) ends upwards in a supersurface with a thick weathering profile that suggests moist and temperate climatic conditions. Unit U2 accumulated mainly during OIS 4 and OIS 3 with prevailing W/E winds. The supersurface between U2 and U3 records a part of OIS 2, with relative low sea level. Sedimentation of unit U3 took place during the Last Deglaciation (radiocarbon and OSL ages) with prevailing W/SW winds, under a temperate moist climate, that became more arid towards the top (Holocene). A major supersurface with an iron crust-like layer (SsFe) developed during the Holocene Climatic Optimum (OIS 1) under wetter and more temperate conditions than before, fossilizing the TLF. The supersurface is covered by younger aeolian dunes (U4, U5, U6, and U7) transported by W - SW winds since the Late Neolithic - Chalcolithic cultural period (̃5.0 ky cal BP).Financial support from Spanish Projects BTE2002-1065 and BTE2002-1691. This is a contribution to IGCP 495 and to the INQUA “Coastal and Marine Processes Commission”

Climate change impacts on coastal areas

El litoral es uno de los medios naturales más transformados por la actividad antrópica, ya sea directa o indirectamente. El 40% de la población mundial vive en la franja costera (un 44% en España), por lo que cualquier alteración del medio natural se convierte en un gran riesgo. Desde la segunda mitad del s.XX, el balance sedimentario ha ido presentando, en general, una tendencia progresivamente negativa debido a actividades humanas, incrementándose los problemas relacionados con la erosión y retroceso costero, a menudo confundidos con una subida del nivel del mar. En los últimos años existe una creciente tendencia a dramatizar sobre el futuro de nuestro litoral, no solo español sino global, a punto de desaparecer por la subida generalizada del nivel del mar que va a arrasar gran parte de los terrenos costeros. Nuestro litoral está enfermo pero para poder entender cuál es el peligro real frente al cambio climático, es necesario entender bien cuál es la problemática concreta de cada sector, es decir cómo es el balance sedimentario real, cuáles son las causas de los posibles desequilibrios, cuál ha sido la tendencia del nivel del mar en un pasado cercano, y sobre todo saber si un determinado sector podría o no adaptarse de forma natural a una subida del nivel del mar, etc. Es decir, tenemos que conocer antes que juzgar.The littoral fringe is a one of the natural environments more highly transformed by human activities, either direct or indirectly. The 40% of world population lives at the coastal area (40% in Spain), so any alteration of this environment becomes seriously risky. Since the second half of 20th century, sedimentary balance present a progressively higher negative trend mainly due to human activities, with a consequent increasing erosion and coastal retreat, in many cases reported as sea level rise. A wide trend to dramatize has arisen these last decades about what is going to happen with the littoral all over the world, with a wide flooding causing the disappearance of all terrains by the sea. Our littoral is ill, but if we want to know which the real illness is and how should we proceed, first we have to know the real problem in each considered site. We should analyse the sedimentary balance for each location in danger, the causes of the disequilibria, the sea level trend during in a near past, and above all, the adaptation capacity to a sea level rise. We should know before giving a diagnostic.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu