Simulation of tsunami induced by a submarine landslide in a glaciomarine margin: the case of Storfjorden LS-1 (southwestern Svalbard Islands)

A modelling approach to understand the tsunamigenic potentiality of submarine landslides will provide new perspectives on tsunami hazard threat, mostly in polar margins where global climatic change and its related ocean warming may induce future landslides. Here, we use the LML- HySEA (Landslide Multilayer Hyperbolic Systems and Efficient Algorithms) numerical model, including wave dispersion, to provide new insights into factors controlling the tsunami characteristics triggered by the Storfjorden LS-1 landslide (southwestern Svalbard). Tsunami waves, determined mainly by the sliding mechanism and the bathymetry, consist of two initial wave dipoles, with troughs to the northeast (Spitsbergen and towards the continent) and crests to the south (seawards) and southwest (Bear Island), reaching more than 3m of amplitude above the landslide and finally merging into a single wave dipole. The tsunami wave propagation and its coastal impact are governed by the Storfjorden and Kveithola glacial troughs and by the bordering Spitsbergen Bank, which shape the continental shelf. This local bathymetry controls the direction of propagation with a crescent shape front, in plan view, and is responsible for shoaling effects of amplitude values (4.2m in trough to 4.3m in crest), amplification (3.7m in trough to 4m in crest) and diffraction of the tsunami waves, as well as influencing their coastal impact times.Junta de Andalucia B-RNM-301-UGR18 P18-RT-3275 RNM 148University of Granada, FEDERAgencia Estatal de Investigacion PID2019-108880RJI00/AEI POL2006-07390/CGL CTM2009-06370-E/AN

Morphological and geological features of Drake Passage, Antarctica, from a new digital bathymetric model

The Drake Passage is an oceanic gateway of about 850 km width located between South America and the Antarctic Peninsula that connects the southeastern Pacific Ocean with the southwestern Atlantic Ocean. It is an important gateway for mantle flow, oceanographic water masses, and migrations of biota. This sector developed within the framework of the geodynamic evolution of the Scotia Arc, including continental fragmentation processes and oceanic crust creation, since the oblique divergence of the South American plate to the north and the Antarctic plate to the south started in the Eocene. As a consequence of its complex tectonic evolution and subsequent submarine processes, as sedimentary infill and erosion mainly controlled by bottom currents and active tectonics, this region shows a varied physiography. We present a detailed map of the bathymetry and geological setting of the Drake Passage that is mainly founded on a new compilation of precise multibeam bathymetric data obtained on 120 cruises between 1992 and 2015, resulting in a new Digital Bathymetric Model with 200 × 200 m cell spacing. The map covers an area of 1,465,000 km2 between parallels 52°S and 63°S and meridians 70°W and 50°W at scale 1:1,600,000 allowing the identification of the main seafloor features. In addition, the map includes useful geological information related to magnetism, seismicity and tectonics. This work constitutes an international cooperative effort and is part of the International Bathymetric Chart of the Southern Ocean project, under the Scientific Committee on Antarctic Research umbrella.This work was supported through projects CTM2014- 60451-C2-02/01, CTM2017-89711-C2-2/1-P and special action CTM2011-13970-E from “Ministerio de Ciencia, Innovación y Universidades” of Spain

3D Geophysical and Geological Modeling of the South Orkney Microcontinent (Antarctica): Tectonic Implications for the Scotia Arc Development

This research was funded by the Spanish Ministry of Science, Innovation and Universities predoctoral Grant PRE2018-084612 linked to the coordinated project TASDRACC (CTM2017-89711-C2-1P and CTM2017-89711-C2-2P), cofounded by the European Union through FEDER fundsThe opening of the Scotia Arc resulted in the final breakup of the land bridge between South America and the Antarctic Peninsula. The South Orkney Microcontinent (SOM) constituted part of this former connection and it is now the largest continental block in the Southern Scotia Arc. We present the first 3D model of the SOM that, given its strategic position and characteristics, allows us to advance the knowledge of the tectonic processes involved in the development of the Scotia Arc. Due to the scarcity of reliable geological data, the initial approximation of the deep structure of the SOM was supported by the calculation of three main geological boundaries from geophysical data: the acoustic basement, the boundary of the magnetic anomaly source and the Moho depth. The 3D model was built, refined and validated by forward modeling and joint inversion of gravity and magnetic data. We have accurately defined the geometry of the sedimentary cover, determined the geometry of the intrusive igneous body causing the Pacific Margin Anomaly (PMA) and mapped the heterogeneity of the crustal thickness. These structural features show a clear relationship to each other and are consistent with an important E-W extension to the east of the SOM during early stages of the Scotia Arc formation, prior to the opening of the Powell Basin.Spanish Government PRE2018-084612, CTM2017-89711-C2-1P, CTM2017-89711-C2-2PEuropean Union through FEDER fund

Active Collapse in the Central Betic Cordillera: Development of the Extensional System of the Granada Basin

The Betic Cordillera was formed by the collision between the Alboran Domain and the South Iberian paleomargin in the frame of the NW–SE convergent Eurasia–Nubia plate boundary. The central region is undergoing a heterogeneous extension that has not been adequately analysed. This comprehensive study addressed it by collecting structural geologic, seismologic, and geodetic data. The region west of the Sierra Nevada is deformed by the extensional system of the Granada Basin, which facilitates E–W to NE–SW extension. Moreover, the southern boundary of Sierra Nevada is affected by a remarkable N–S extension related to E–W normal to normal–dextral faults affecting the shallow crust. However, geologic and geodetic data suggest that the western and southwestern Granada Basin boundary constitutes a compressional front. These data lead to the proposal of an active extensional collapse from the uplifted Sierra Nevada region to theW–SW–S, over an extensional detachment. The collapse is determined by the uplift of the central Betics and the subsidence in the Alboran Basin due to an active subduction with rollback. Our results indicate that the central Betic Cordillera is a good example of ongoing extensional collapse in the general context of plate convergence, where crustal thickening and thinning simultaneously occurBARACA (PID2022-136678NB-I00 AEI/FEDER)P18-RT-3275, B-RNM-301-UGR18 (Junta de Andalucía/FEDER)Programa Operativo FEDER Andalucía 2014-2020 Ref. 126344 (University of Jaén)POAIUJA 2023/2024 (University of Jaén) projects and the Andalusian research groups RNM-148, RNM-282RNM-370University of GranadaSpanish Ministry of Science, Innovation, and Universities (PTA2019-017685-I/AEI

Stochastic Modeling of the Al Hoceima (Morocco) Aftershock Sequences of 1994, 2004 and 2016

The three aftershock sequences that occurred in Al Hoceima, Morocco, in May 1994 (Mw 6.0), February 2004 (Mw 6.4) and January 2016 (Mw 6.3) were stochastically modeled to investigate their temporal and energetic behavior. A form of the restricted trigger model known as the restricted epidemic type aftershock sequence (RETAS) was used for the temporal analysis of the selected series. The best-determined fit models for each sequence differ based on the Akaike information criteria. The revealed discrepancies suggest that, although the activated fault systems are close (within 10 to 20 km), their stress regimes change and shift across each series. In addition, a stochastic model was presented to study the strain release following a specific strong earthquake. This model was constructed using a compound Poisson process and depicted the progression of the strain release during the aftershock sequence. The proposed model was then applied to the data. After the RETAS model was used to evaluate the behavior of the aftershock decay rate, the best-fit model was obtained and integrated into the strain-release stochastic analysis. By detecting the potential disparities between the observed data and model, the applied stochastic model of strain release allows for a more comprehensive examination. Furthermore, comparing the observed and expected cumulative energy release numbers revealed some variations at the start of all three sequences. This demonstrates that significant aftershock clusters occur more frequently shortly after the mainshock at the start of the sequence rather than if they are assumed to occur randomly.Consejeria de Economia, Conocimiento, Empresa y Universidad, in the frame of the Programa Operativo FEDER Andalucia Junta de Andalucia CGL2016-80687-R B-RNM-301UGR18 RNM148 P18-RT-327

The relief of the Betic Cordillera

11 páginas, 13 figuras.[EN] The Betic Cordillera is an Alpine orogen created by the collision of the Africa and Eurasian plates. Although this alpine deformation started 60 millions years ago, the present relief is related to tectonic processes occurred during approximately the last 8 millions years, from the Late Tortonian to the Present. During this period the Betic Cordillera has been subject to regional NNW-SSE compression and ENE-WSW extension, with local heterogeneities. These compressive stresses have created numerous EW/ ENE-WSW active folds, some of them probably related to thrusts. Present topography is controlled mainly by these active folds, where uplifted sectors coincide with antiforms and depressions with synforms. ENE-WSW extension is mainly accommodated by NW-SE normal faults, which create a stepped relief. In addition, several strike-slip faults as the Eastern Betic Shear Zone also exist, but associated vertical movements are not noticeable. A regional uplift is produced in the Betic Cordillera from the Late Tortonian to the Present caused by these structures. This active uplift is maximum in Sierra Nevada, where it reaches a value of about 0.5 mm/year, and progressively diminishes in all directions.[ES] La Cordillera Bética es un orógeno alpino resultado de la colisión entre las placas Africana y Euroasiática. Aunque la deformación alpina comenzó hace aproximadamente 60 millones de años, el relieve actual está asociado principalmente a los procesos tectónicos ocurridos en los últimos 8 millones de años, desde el Tortoniense superior hasta la actualidad. En este último periodo la Cordillera Bética ha estado sometida a un campo de esfuerzos regional de compresión NNO-SSE y a extensión perpendicular ENE-OSO, aunque variable en el detalle. Los esfuerzos compresivos han producido numerosos pliegues, de dirección media E-O/ENE-OSO, algunos de ellos probablemente asociados a cabalgamientos. Estos pliegues, la mayoría todavía activos, han formado un relieve en el que los antiformes coinciden con las principales sierras de la Cordillera, y los sinformes con depresiones. La extensión ENE-OSO se acomoda por fallas normales, especialmente de dirección NO-SE, que se sitúan en los bordes de las sierras, y producen un relieve escalonado. Además, existen fallas activas de salto en dirección entre las que destaca la Zona de Cizalla de la Bética oriental, aunque tiene una impronta en el relieve mucho menos destacada. A favor de todas estas estructuras se está produciendo una elevación regional de la Cordillera Bética desde el Tortoniense superior hasta la actualidad. Esta elevación, todavía activa, tiene un valor máximo alrededor de 0.5 mm/año en Sierra Nevada y disminuye progresivamente en otras partes del orógeno.Este trabajo ha sido parcialmente financiado por los proyectos de investigacicón BTE2001-5230-E, CGL200401636/BTE, CGL2006-06001, CSD2006- 00041 y por la Generalitat Valenciana (GRUPOS03/ 085, OCYT).Peer reviewe

Gravity anomalies and orthogonal box fold development on heterogeneous basement in the Neogene Ronda Depression (Western Betic Cordillera)

28 páginas, 6 figuras.-- PDF es el manucristo aceptado del autor (post-print).The Ronda Depression constitutes a Neogene intramontane basin located in the external zones of the Western Betic Cordillera. Major deformation structures affect only the southwestern part of its sedimentary infill and consist of NNE–SSW and WNW–ESE box folds that developed simultaneously. New gravity data reveal two negative NNE–SSW elongated Bouguer anomalies, unrelated to basin depocenters, but corresponding to the accumulation of low-density ductile Triassic basement rocks in the core of antiforms or directly under the northwestern undeformed sedimentary infill. The Subbetic basement is also deformed by early-Burdigalian to Serravallian NNE–SSW folds and thrusts, although there is no clear continuity with those affecting the late-Miocene sedimentary infill. The aim of this contribution is to describe in detail the late-Miocene folds that deform the Ronda Depression, as well as to discuss the role of the basement nature on their reactivation. The reactivation of the pre-Tortonian folds, due to the heterogeneous distribution of evaporitic Triassic rocks in the basement as well as the presence of rigid limestones on the southwestern basin boundary, determined the simultaneous orthogonal fold development that only evidence local deformation.This study was supported by a PhD grant to the first author from Spain´s Ministerio de Educación y Ciencia and the projects CSD2006-00041 and CGL 2006-06001 (MEC) and Junta de Andalucía.Peer reviewe

Combined use of the GGSFT data base and on Board Marine Collected Data to Model the Moho Beneath the Powell Basin, Antarctica

The Powell Basin is a small oceanic basin located at the NE end of the Antarctic Peninsula developed during the Early Miocene and mostly surrounded by the continental crusts of the South Orkney Microcontinent, South Scotia Ridge and Antarctic Peninsula margins. Gravity data from the SCAN 97 cruise obtained with the R/V Hespérides and data from the Global Gravity Grid and Sea Floor Topography (GGSFT) database (Sandwell and Smith, 1997) are used to determine the 3D geometry of the crustal-mantle interface (CMI) by numerical inversion methods. Water layer contribution and sedimentary effects were eliminated from the Free Air anomaly to obtain the total anomaly. Sedimentary effects were obtained from the analysis of existing and new SCAN 97 multichannel seismic profiles (MCS). The regional anomaly was obtained after spectral and filtering processes. The smooth 3D geometry of the crustal mantle interface obtained after inversion of the regional anomaly shows an increase in the thickness of the crust towards the continental margins and a NW-SE oriented axis of symmetry coinciding with the position of an older oceanic spreading axis. This interface shows a moderate uplift towards the western part and depicts two main uplifts to the northern and eastern sectors

The Campo de Dalias GNSS Network Unveils the Interaction between Roll-Back and Indentation Tectonics in the Gibraltar Arc

Funding: Junta de Andalucia; European Regional Development Fund; grant numbers: AGORA P18-RT-3275, PAPEL B-RNM-301-UGR18. Programa Operativo FEDER-Andalucia 2014–2020 Project ref. 1263446; University of Jaén; CEACTEMA; grant number: POAIUJA 21/22. Junta de Andalucía (Andalusian Board); grant numbers: RNM-148, RNM-282, RNM-370. V.T.S. was supported by the FPU PhD grant (16/04038).The Gibraltar Arc includes the Betic and Rif Cordilleras surrounding the Alboran Sea; it is formed at the northwest–southeast Eurasia–Nubia convergent plate boundary in the westernmost Mediterranean. Since 2006, the Campo de Dalias GNSS network has monitored active tectonic deformation of the most seismically active area on the north coast of the Alboran Sea. Our results show that the residual deformation rates with respect to Eurasia range from 1.7 to 3.0 mm/year; roughly homogenous west-southwestward displacements of the northern sites occur, while the southern sites evidence irregular displacements towards the west and northwest. This deformation pattern supports simultaneous east-northeast–west-southwest extension, accommodated by normal and oblique faults, and north-northwest–south-southeast shortening that develops east-northeast–west-southwest folds. Moreover, the GNSS results point to dextral creep of the main northwest–southeast Balanegra Fault. These GNNS results thus reveal, for the first time, present-day interaction of the roll-back tectonics of the Rif–Gibraltar–Betic slab in the western part of the Gibraltar Arc with the indentation tectonics affecting the eastern and southern areas, providing new insights for improving tectonic models of arcuate orogens.FPU 16/04038University of Jaén POAIUJA 21/22European Regional Development Fund 1263446, AGORA P18-RT-3275, PAPEL B-RNM-301-UGR18Junta de Andalucía RNM-148, RNM-282, RNM-37