Reappraisal of the 1863 huércal‐overa earthquake (Betic cordillera, se spain) by the analysis of esi‐07 environmental effects and building oriented damage

This work reviews the 1863 Huércal‐Overa earthquake (VI‐VII EMS) based on the environmental seismic intensity scale (ESI‐07) and oriented archaeoseismological building damage. The performed analysis identifies 23 environmental effects (EEEs) and 11 archaeoseismological effects (EAEs), completing a total of 34 intensity data‐points within the intensity zone ≥ VI EMS. The new ESI intensity data quintuplicate the previous intensity data‐points ≥ VI EMS (five localities) for this event. Sixteen of the identified EEEs indicate the occurrence of intensity VII‐VIII within the Almanzora valley, south of Huércal‐Overa, over an area of ca. 12–15 km2. Anomalies in water bodies, slope movements, hydrogeological anomalies, ground cracking, and other effects (gas emissions, tree shaking) are the more diagnostic EEEs—with one of them indicating a local maximum intensity of VIII‐IX ESI‐07 (Alboraija lake). Environmental earthquake damage of intensity ≥ VI covers an area of c. 100 km2, compatible with a VIII ESI intensity event. The spatial distribution of EEEs and EAEs indicates that the zone of Almanzora River Gorge, which was depopulated during the earthquake epoch, was the epicentral area, and compatible with seismotectonic data from active shallow blind thrusting beneath the Almagro Range. The use of ESI data in nearly unpopulated areas help to fill gaps between damaged localities (EMS data) multiplying intensity data‐points, providing a better definition of the intensity zones and offering a geological basis to look for suspect seismic sourcesCGL2015-67169-

The AD 1755 Lisbon Earthquake-Tsunami: Seismic source modelling from the analysis of ESI-07 environmental data

This work presents a macroseismic analysis of the AD 1755 Lisbon Earthquake-Tsunami event by means of the combination of intensity data derived from the EMS-98 scale and the ESI-07 scale (Environmental damage). About 600 records of secondary earthquake environmental effects (EEEs) for the whole Spain have been used to define intensities, focused on the SW portion of the Iberian Peninsula. The Spanish data have been complemented with 308 EEEs records from Portugal. The analyses indicate maximum intensities of X EMS-ESI along the Atlantic margin of the Iberian Peninsula with 76 records of Tsunami environmental effects (TEEs). An important amplification (VIII – VII) occurred all along the Guadalquivir basin and the adjacent Betic front at epicentral distances of 300–700 km. In these zones 55 records of ground effects (ground cracks, Liquefactions and slope movements) are catalogued. In the rest of the territory of the Peninsula the most widespread effects were hydrogeological changes with 505 records in Spain and 196 in Portugal (total 701 records) covering all the intensity levels. Increase of flow discharges in springs and elevation of water level in wells was the common groundwater response to seismic shacking, especially in SW Iberia. In this zone water elevation in wells was between 5 and 3 m and persistent increases of discharges long-lasting (several days to two months). Persistent discharges on springs were linked in 143 cases to important SW-NE crustal faults (e.g., Alentejo-Plasencia Fault). From the Intensity distribution the historic seismic scenarios are explored by means of the development of empirical ShakeMaps. These consider the three classical seismic sources proposed for this earthquake: Gorringe Bank (G); Marques de Pombal Fault (M) and Atlantic delamination beneath the Gulf of Cadiz (C). However, individually these seismic sources are too small and unable to generate the resulting seismic scenario depicted by the intensity map developed in this work, with onshore seismic accelerations (PGA) up to 0.82 g. These acceleration values and the great amplification experienced throughout the Guadalquivir basin (0.34–0.52 g) are only possible considering a combination of the three seismic sources (GMC Source) probably related to shallow subduction or lithospheric delamination beneath SW Iberia and the Gulf of Cadiz. This will suggest an NNE-SSW offshore rupture length of 350–360 km with an overall rupture area of c. 84,500 km2 resulting in an event magnitude 8.6 Mw calculated from empirical relationships. The results demonstrate the efficacy of these kind of approaches for better identifying and modelling seismic sources for historical eventsThis work was supported by the Spanish Research Project MINECOFEDER CGL2015-67169-P (QTECSPAIN - USAL). It is a contribution of the Earthquake Geology Group (TPPT) of the INQUA TERPRO Commission. Authors are grateful to the constructive comments of Joao Fonseca and an anonymous reviewer who significantly improved the content of this pape

Evolution of the Júcar-Cabriel fluvial system on the Mediterranean watershed of the Iberian Peninsula (Valencia, eastern Spain)

This study presents the characterization and chronology of the Quaternary terrace sequence developed in the confluence zone of the Júcar and Cabriel river valleys. The study area covers a radius of 10 km from the confluence of the two valleys near the locality of Cofrentes (Valencia). It is located in the northern zone of the Ayora-Cofrentes Graben in the northeastern sector of the External Prebetic Zone adjacent to southern Iberian Chain. This N-S graben is an inherited tectonic feature with an axial salt wall subject to different periods of fluvial dissection and refilling since at least the end of the Messinian Salinity Crisis (MSC). Regional isostatic uplift and local uplift and subsidence processes related to salt flow and dissolution during the Quaternary period, favored by fluvial entrenchment and terrace development. The terrace system and the previous pre-incision erosional and depositional surfaces are analyzed from a geomorphological point of view. The terrace system only develops within the soft Mio-Pliocene sedimentary fill of the graben, whilst upstream and downstream this zone the studied valleys develop important gorges (canyons) carved in the Cretaceous tablelands (Caroch Massif) and Mio-Pliocene deposits (Llanura Manchega). The geochronological control is established from 20 numerical ages obtained by different dating methods, such us Electron Spin Resonance (ESR), Optically Stimulated Luminescence (OSL) in detrital sequences and Th/U series in calcareous tufa deposits. Additionally, four K/Ar dates available for volcanic materials disrupting the upper and oldest terrace have been considered. A total of 14 terrace levels were identified between +130–135 m (T1) and +3–4 m (T14) of relative height above the river thalwegs. The T1 has an approximate age of c. 1.6–2.0 M.a. as indicate the age of the volcanic materials from the Agras Volcano intruded in the terrace, marking the onset of Quaternary fluvial dissection in the zone. The obtained geochronological data indicate that the Lower-Middle Pleistocene boundary is slightly above T6 (+60–65 m), which has an ESR age of 577 ± 43 ka. This terrace also documents the onset of the most important period of rise of the salt within the graben interfering drainage development. The geochronological data indicate the occurrence of a second eruptive event during the second half of the Middle Pleistocene related to the terraces T7 (+50 m) and T8 (+35–40 m), updating the volcanic activity in the zone. The beginning of the Upper Pleistocene is recorded by the top sequences of the T9 terrace (+25–30 m) where numerous OSL and Th/U data have been obtained with ages between ca. 105 and 81 ka (MIS 5). However, these young terraces (T8 to T13) are thickened (8–10 m) recording Middle Pleistocene sediments in their basal sequences with ages between ca. 193 and 137 ka (MIS 6). The study provides important data on valley evolution under the interference of volcanic activity, salt –related deformation (diapirism, solution subsidence) and fluvial incision fostered by the rise of the axial diapir (salt wall) protruding the graben since at least the Brunhes-Matuyama boundary. The analyzed fluvial evolution documents interesting cases of river capture, drainage antecedence and tectonic adaptation of the drainage throughout the Quaternary Period. The paper also poses interesting geochronological data on the long-term Quaternary evolution of Mediterranean valleys in the Iberian Peninsula, poorly explored to the dat

Archaeoseismological Evidence of Seismic Damage at Medina Azahara (Córdoba, Spain) from the Early 11th Century

The “Caliphal City of Medina Azahara” was built in 936–937 CE or 940–941 CE (depending on the source) by the first Caliph of al-Andalus Abd al-Rahman III, being recently inscribed (2018) on the UNESCO World Heritage List. The abandonment and destruction of the city have been traditionally related to the civil war (“fitna”) that started between 1009 and 1010 CE. However, we cannot rule out other causes for the rapid depopulation and plundering of the city just a few decades after its foundation. The archaeoseismological study provides the first clues on the possible role played by an earthquake in the sudden abandonment and ruin of the city. Eleven different types of Earthquake Archaeological Effects (EAEs) have been identified, such as dropped key stones in arches, tilted walls, conjugated fractures in brick-made walls, conjugated fractures and folds in regular pavements and dipping broken corners in columns, among others. Besides that, 163 structural measures on EAEs were surveyed resulting in a mean ground movement direction of N140°–160° E. This geological structural analysis clearly indicates a building-oriented damage, which can be reasonably attributed to an earthquake that devastated Medina Azahara during the 11st or 12th centuries CE. If this were the case, two strong earthquakes (≥VIII MSK/EMS) occurred in 1024–1025 CE and 1169–1170 CE could be the suspected causative events of the damage and destruction of the cit

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

Análisis arqueosismológico del conjunto arqueológico romano de Mulva- Munigua (Sevilla, España). Resultados preliminares

El conjunto arqueológico romano de Mulva-Munigua (Sevilla, España) presenta daños en las edificaciones que pueden ser interpretadas como resultado de la ocurrencia de un evento sísmico (Efectos Arqueológicos de los Terremotos: EAEs) a finales del siglo III A.D., fecha coincidente con el inicio del periodo de declive económico de este asentamiento romano. Para intentar establecer el posible origen sísmico de las deformaciones, se ha procedido al inventario y análisis de las estructuras deformadas presentes en el yacimiento. No obstante, algunas de estas deformaciones también se pueden interpretar como resultado de procesos gravitaciones asociados a la ladera Este de la colina sobre la que se sitúa parte del yacimiento. Las direcciones de máxima deformación (ey) obtenidas del análisis de EAEs indica dos direcciones preferentes de la deformación (o movimiento preferente del terreno): NNO-SSE y ENEOSO. Aunque los datos presentan una dispersión importante, se puede establecer que la orientación principal NNO-SSE es compatible con un evento sísmico situado en el borde norte del Valle del Guadalquivir. La orientación ENE-OSO podría relacionarse con un evento posterior, o más seguramente con procesos de ladera de carácter cosísmico o no.The Roman archaeological site of Mulva-Munigua (Sevilla, Spain) displays building damage features suggesting a seismic origin (Earthquake Archaeological Effects: EAEs). The proposed seismic event could be tentatively dated in the late 3rd century AD, coinciding with the beginning of the economic fall of the Roman Empire at Iberia. However, some of the recorded EAEs can be also interpreted as a result of intervening slope movements in the eastern hillslope of this roman site. The inventory and analysis of the proposed EAEs make possible to discern between seismic oriented damage and other causes. In spite of the data show a significant dispersion, their analysis result in two different orientations of maximum deformation (ey) or preferential ground movement: NNW-SSE and ENE-WSW. The main ey orientation (NNW-SSE) can be tentatively related to a seismic event occurred in the environs of the northern border of the Guadalquivir Depression. The secondary orientation (ENE-WSW) can be interpreted as a consequence of latter slope movements triggered (or not) by other ancient earthquakes

Utilización de Shakemaps y efectos geológicos como escenarios para simulacros en gestión de desastres por terremoto

Se ha realizado un mapa de intensidad macrosísmica y aceleración del terreno (ShakeMap) de un terremoto SIMULADO, dentro de un macro ejercicio de emergencias Nivel III, propuesto por la Unidad Militar de Emergencias (UME), junto con Protección Civil y demás autoridades. El terremoto SIMULADO se localiza en la región de Murcia, con una magnitud de Mw 6.5, a 11 km de profundidad y asociado a un segmento activo de la Falla de Alhama de Murcia (FAM). El principal objetivo en este trabajo, es la génesis de mapas científicos útiles para las autoridades durante la gestión de la emergencia, mostrando las capacidades reales de gestión de un desastre natural de esta magnitud

Quaternary fossil horses within the Prados-Guatén Depression (Pantoja de La Sagra, Toledo)

Durante la primera reunión de campo del Grupo Madrileño de Cuaternario (GQM-AEQUA) se localizaron restos fragmentarios de dentición de caballos fósiles en los antiguos areneros de Pantoja de La Sagra (Toledo), actualmente en proceso de desmantelamiento y relleno. Ante la posibilidad de deterioro y pérdida los restos fueron recolectados y trasladados al Museo Nacional de Ciencias Naturales (CSIC, Madrid) donde se ha procedido a su análisis. Las piezas fósiles analizadas responden a un maxilar izquierdo con tres piezas dentales in situ (molares y premolares), y otras siete más aisladas. Todos los dientes aislados, junto con el fragmento de maxilar existente, corresponden a un adulto joven. Los restos fósiles se encontraban asociados a un nivel de arenas fluviales situado unos cuatro metros por debajo de la superficie de la Terraza de +15 m de la Depresión Prados-Guatén definida como un nivel perteneciente al tránsito Pleistoceno inferior-medio, del antiguo Sistema fluvial Manzanares-Guatén por Silva (1988). En concreto los niveles superiores de esta terraza han sido interpretados como resultado de la superposición de los últimos depósitos del antiguo sistema fluvial y los primeros asociados al relleno de la Depresión por tributarios de área fuente más local tras su abandono como consecuencia del proceso de captura del valle inferior del Manzanares por parte del Río Jarama al SW de la Ciudad de Madrid (Silva et al., 1988). Los caracteres morfológicos y morfométricos de las piezas dentarias permiten identificarlos como Equus ferus cf. mosbachensis cuya distribución bioestratigráfica abarca la parte final del Pleistoceno Medio (c.a. 500-200 ka B.P.). Junto a los restos fósiles aparecieron también escasos fragmentos líticos correspondientes a productos de lascado en sílex de difícil atribución tecnológica. Los restos fósiles analizados, indican que el depósito extensivo de arenas fluviales en el eje de la Depresión, culminó durante el final del Pleistoceno medio, y que la dinámica fluvial de la Depresión tras su proceso de abandono fue de hecho más activa de lo que se pensaba con la instalación de sistemas de arroyos relevantes alimentados por cabeceras locales antes del encajamiento definitivo actual de los arroyos Prados y Guatén.During the first field-meeting of the Madrid Quaternary Research Group (GQM-AEQUA) several fossil teeth remnants of horses were localised at the ancient sand-quarries of Pantoja de La Sagra (Toledo), which presently are abandoned and refilling in progress. The possibility of deterioration and loss of the localised fossils remnants induced by the quarry works, they were collected and taken away to the Museo Nacional de Ciencias Naturales (CSIC, Madrid) for their preservation and analysis. Fossil remains correspond to a left maxilla with two in situ molars, another one inset on its alveolar cavity, fragments of premolar cavities, as well as other seven more isolated teeth. These fossils were outcropping in a sandy level at four meters below the +15 m fluvial terrace surface of the axial sector of de Prados-Guatén Depression, which is considered the last fluvial level belonging to the ancient Manzanares-Guatén fluvial system during the Lower-Middle Pleistocene transit (Silva, 1988). In detail, the upper fluvial sediments of this particular terrace level were interpreted as the result of the overlapping between the last materials deposited by the ancient Manzanares-Guatén fluvial system and the first ones resulting from the readjustment of former tributaries after the abandonment of the Depression caused by fluvial capture of the Lower Manzanares Valley SW Madrid City. The morphological features of the oclusal surface of the horse teeth and morphometric comparative analyses indicate that they belong to the specie Equus ferus, and probably to the subspecie mosbachensis. However due to the bad definition of this group in Europe and the few individuals analysed the better classification is Equus ferus cf. mosbachensis. The bioestratigraphic distribution of this fossil horse group in Europe extends on the upper part of the Middle Pleistocene (c.a. 500-200 ka B.P.). Few lithic artefacts outcropped also associated to the fossil remains, constituted by laminar flakes of hard technological classification. Fossil remains analysed in this work joint to the unique previous quaternary fossil mammal described for the Prados-Guatén Depression constituted by Mammuthus meridionalis NESTI of the former quarry of Esquivias adjacent to the AVE railway line (Silva et al., 1988b; 1999). The chronostratigraphic attribution of the fossil horses (Upper Middle Pleistocene) described here indicate that fluvial sedimentary activity within the Depression was relevant after its abandonment. Ancient tributaries of the former Manzanares-Guatén fluvial system, feed by local-intrabasinal headwaters, reworked the previous sandy sediments triggering multiepisodic deposition during the upper part of the Middle Pleistocene, before the more recent eventual incision of present streams dissecting the Depression

Análisis de la deformación en la Península Ibérica a partir del estudio de mecanismos focales, implicaciones en la peligrosidad sísmica.

Se han analizado 682 mecanismos focales de terremotos localizados en la Península Ibérica y zonas próximas. Aplicando métodos de determinación del tensor de deformación (Modelo de Deslizamiento), se han obtenido diferentes resultados para cada uno de los mecanismos focales: (1) plano de falla entre los dos planos nodales del mecanismo, (2) orientación de máximo acortamiento horizontal (ey), (3) factor de forma de tensor de deformación (k’) y (4) tipo de falla. Con estos datos se pueden realizar análisis regionales y locales de las características de la fracturación activa en el área considerada: (a) caracterización de la fracturación, (b) orientación de máximo acortamiento horizontal, (c) zonación en función del tipo de falla y del factor de forma del tensor de deformación. Este tipo de información puede ser muy útil a la hora de realizar tanto diferentes análisis locales de la peligrosidad sísmica, como para incorporar a los catálogos sísmicos terremotos históricos destructivos sin información de la fuente sísmica

Strain analysis in the Iberian Peninsula from focal mechanism solutions, seismic hazard impacts

Se han analizado 682 mecanismos focales de terremotos localizados en la Península Ibérica y zonas próximas. Aplicando métodos de determinación del tensor de deformación (Modelo de Deslizamiento), se han obtenido diferentes resultados para cada uno de los mecanismos focales: (1) plano de falla entre los dos planos nodales del mecanismo, (2) orientación de máximo acortamiento horizontal (ey), (3) factor de forma de tensor de deformación (k’) y (4) tipo de falla. Con estos datos se pueden realizar análisis regionales y locales de las características de la fracturación activa en el área considerada: (a) caracterización de la fracturación, (b) orientación de máximo acortamiento horizontal, (c) zonación en función del tipo de falla y del factor de forma del tensor de deformación. Este tipo de información puede ser muy útil a la hora de realizar tanto diferentes análisis locales de la peligrosidad sísmica, como para incorporar a los catálogos sísmicos terremotos históricos destructivos sin información de la fuente sísmica.We analysed 682 earthquake focal mechanism solutions located in the Iberian Peninsula and nearby areas. We have obtained different parameters applying methods of determination of the strain tensor (Slip Model): (1) the fault plane between the nodal planes of the focal mechanism, (2) the orientation of the maximum horizontal shortening (ey), (3) the strain shape factor (k`) and (4) the type of fault. With these data, regional and local analysis of active faulting can be carried out in Spain: (a) fracture characterization, (b) the orientation of maximum horizontal shortening, (c) spatial zonation according to the type of fault and (d) the strain shape factor. These results can be useful for seismic hazards studies of local zones and for including destructive historical earthquakes in the seismic catalogs.Depto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu