Suchergebnisse

This study was supported by the Spanish projects DAMAGE (CGL2016-80687-R AEI/FEDER), FAUCES (CTM2015-65461-C2-1-R), RNM148, B-RNM-301-UGR18 and AGORA P18-RT-3275 Junta de Andalucia. The authors appreciate the IHS-Kingdom educational license. Research partially funded by the Programa Operativo FEDER Andalucia 2014-2020, call made by the University of Jaen 2018. The ICM-CSIC authors acknowledge Severo Ochoa funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2019-000928-S). ; Tsunamis are triggered by sudden seafloor displacements, and usually originate from seismic activity at faults. Nevertheless, strike-slip faults are usually disregarded as major triggers, as they are thought to be capable of generating only moderate seafloor deformation; accordingly, the tsunamigenic potential of the vertical throw at the tips of strike-slip faults is not thought to be significant. We found the active dextral NW–SE Averroes Fault in the central Alboran Sea (westernmost Mediterranean) has a historical vertical throw of up to 5.4 m at its northwestern tip corresponding to an earthquake of Mw 7.0. We modelled the tsunamigenic potential of this seafloor deformation by Tsunami-HySEA software using the Coulomb 3.3 code. Waves propagating on two main branches reach highly populated sectors of the Iberian coast with maximum arrival heights of 6 m within 21 and 35 min, which is too quick for current early-warning systems to operate successfully. These findings suggest that the tsunamigenic potential of strike-slip faults is more important than previously thought, and should be taken into account for the re-evaluation of tsunami early-warning systems. ; Spanish project DAMAGE CGL2016-80687-R ; Spanish project FAUCES CTM2015-65461-C2-1-R ; AGORA P18-RT-3275 ; Programa Operativo FEDER Andalucia 2014-2020 ; University of Jaen ; Spanish government through the "Severo Ochoa Centre of Excellence" accreditation CEX2019-000928-S RNM148 B-RNM-301-UGR18

This study was supported by projects CGL2016-80687-R AEI/FEDER, P18-RT-3275, B-RNM-301-UGR18 and RNM148 (Junta de Andalucia/FEDER); ALBAMAR JCJC ANR-17-CE030004; the EUROFLEETS program (FP7/2007-2013; no 228344); project FICTS-2011-03-01; and the FPU PhD grant (16/04038), and also by the Spanish Government through the 'Severo Ochoa Centre of Excellence' accreditation (CEX2019-000928-S). ; The IHS KINGDOM software package was utilized in the present study. We also to the marine surveys, MARLBORO2 and SARAS (https://campagnes.flotteoceanographique.fr/ campagnes/12450090/; https://campagnes.flotteoceanographique. fr/campagnes/12000010/). ; Automation of the throw backstripping method has proven to be an effective tool for the determination of the evolution of tectonic activity in wide fault zones. This method has been applied to the Al Hoceima Bay (southwesternmost Mediterranean, Alboran Sea) for a time period covering the last 280 kyr on 672 faults imaged on 265 high-resolution seismic reflection profiles. This area was affected by major earthquakes and corresponds to a transtensional basin deformed by growth faults. The automated application of throw backstripping allowed for a faster deciphering of the migration of tectonic activity. Results show a westward migration of the deformation with quickly increasing deformation rates in the most recent time frames near Al Hoceima, one of the most populated cities. This migration is in agreement with the current seismicity, the GPS data, and recent brittle deformation data. Vertical throw rates of up to 0.47 mm/year have been calculated, for the most recent time periods, in segments of the Bokkoya fault zone. The westward migration of the deformation fits with the reconstruction suggested by the westernmost Mediterranean geodynamic models during the Pleistocene epoch, and it might be the consequence of the interaction between the northwest (NW) movement of the South Alboran indenter and the back Rif south-westward displacement. The highly accurate constraints of the evolution of the tectonic activity offered by this automation will substantially improve the seismic hazard assessment. ; Junta de Andalucia European Commission CGL2016-80687-R AEI/FEDER P18-RT-3275 B-RNM-301-UGR18 RNM148 ; ALBAMAR JCJC ANR-17-CE030004 ; EUROFLEETS program (FP7/2007-2013) 228344 ; German Research Foundation (DFG) 16/04038 ; Spanish Government through the 'Severo Ochoa Centre of Excellence' accreditation CEX2019-000928-S ; FICTS-2011-03-01

The comments of two anonymous reviewers have improved the quality of this manuscript. This study was supported by projects CGL2016-80687-R AEI/FEDER , P18-RT-3275 , B-RNM-301-UGR18 and RNM148 ( Junta de Andalucía/FEDER ). Y.M.M was supported by NASA under award number 80GSFC17M0002 . V.T.S. was supported by the FPU PhD grant ( 16/04038 ). ICM-CSIC author acknowledges the Severo Ochoa funding from the Spanish government through the " Severo Ochoa Centre of Excellence " accreditation ( CEX2019-000928-S ). University of Granada supported this study by funding the APC for publishing as an Open Access articile through an agreement with Elsevier. ; In the Alboran Sea there are a few well exposed Neogene and Quaternary volcanic zones, often geographic highs, that are generally associated with magnetic anomalies. In this paper, we present a characterization of these magnetic anomalies based on a recent and accurate magnetic data compilation for the Abloran Sea area. The anomalies reveal the distribution of magmatism and shed light into the discussion about the origin and evolution of the westernmost Mediterranean. One of the most relevant magnetic anomalies is the Nador dipole, which extends from the Gourougou volcano to the Chafarinas Islands, and is related to an E-W crustal scale intrusion. However, the main NE-SW elongated continuous dipoles of the central Alboran Sea are not related to any surface structure, but they are parallel to the Alboran Ridge, which is the main volcanic high in the Alboran Sea, and are located to the north of it. These anomalies extend discontinuously eastward along the NW-SE dipoles located along the Yusuf fault zone. The results of our 2D magnetic forward modeling suggest that the causative bodies of these main magnetic dipoles are deep igneous bodies. According to the tectonic evolution of the region, and the high magnetic susceptibility values obtained, these igneous bodies probably are made of a basic igneous rocks. Their emplacement may represent the westward tip of the rift axis of the AlKaPeCa Domain, which is related to the Oligocene-Miocene NW-SE extension, and associated with the southern slab retreat stage and oceanic spreading of the Algerian basin. Afterwards, these bodies were displaced toward the west, together with the Alboran Domain, and affected by the STEP fault located at its southern limit. Since the Late Miocene, the north Alboran Ridge elongated intrusions acted as a backstop that conditioned the folding and uplift of the Alboran Ridge in a tectonic indentation setting. In this setting, the STEP fault is deformed and the eastern part of the bodies were segmented along the Yusuf transtensional fault system. Simultaneously, the E-W crustal body related to the Nador magnetic dipole was emplaced, possibly evidencing a slab tearing process. The deep seated basic igneous bodies constitute main crustal heterogeneities that reveal and drive the Alboran Sea tectonic inversion. ; FPU 16/04038 ; Spanish government CEX2019-000928-S ; National Aeronautics and Space Administration 80GSFC17M0002 ; Universidad de Granada ; Junta de Andalucía

14 pages, 9 figures, supplementary data https://doi.org/10.1016/j.margeo.2021.106696 ; In the Alboran Sea there are a few well exposed Neogene and Quaternary volcanic zones, often geographic highs, that are generally associated with magnetic anomalies. In this paper, we present a characterization of these magnetic anomalies based on a recent and accurate magnetic data compilation for the Abloran Sea area. The anomalies reveal the distribution of magmatism and shed light into the discussion about the origin and evolution of the westernmost Mediterranean. One of the most relevant magnetic anomalies is the Nador dipole, which extends from the Gourougou volcano to the Chafarinas Islands, and is related to an E-W crustal scale intrusion. However, the main NE-SW elongated continuous dipoles of the central Alboran Sea are not related to any surface structure, but they are parallel to the Alboran Ridge, which is the main volcanic high in the Alboran Sea, and are located to the north of it. These anomalies extend discontinuously eastward along the NW-SE dipoles located along the Yusuf fault zone. The results of our 2D magnetic forward modeling suggest that the causative bodies of these main magnetic dipoles are deep igneous bodies. According to the tectonic evolution of the region, and the high magnetic susceptibility values obtained, these igneous bodies probably are made of a basic igneous rocks. Their emplacement may represent the westward tip of the rift axis of the AlKaPeCa Domain, which is related to the Oligocene-Miocene NW-SE extension, and associated with the southern slab retreat stage and oceanic spreading of the Algerian basin. Afterwards, these bodies were displaced toward the west, together with the Alboran Domain, and affected by the STEP fault located at its southern limit. Since the Late Miocene, the north Alboran Ridge elongated intrusions acted as a backstop that conditioned the folding and uplift of the Alboran Ridge in a tectonic indentation setting. In this setting, the STEP fault is deformed and the eastern part of the bodies were segmented along the Yusuf transtensional fault system. Simultaneously, the E-W crustal body related to the Nador magnetic dipole was emplaced, possibly evidencing a slab tearing process. The deep seated basic igneous bodies constitute main crustal heterogeneities that reveal and drive the Alboran Sea tectonic inversion ; This study was supported by projects CGL2016-80687-R AEI/FEDER, P18-RT-3275, B-RNM-301-UGR18 and RNM148 (Junta de Andalucía/FEDER). Y.M.M was supported by NASA under award number 80GSFC17M0002. V.T.S. was supported by the FPU PhD grant (16/04038). ICM-CSIC author acknowledges the Severo Ochoa funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2019-000928-S). University of Granada supported this study by funding the APC for publishing as an Open Access articile through an agreement with Elsevier ; Peer reviewed

9 pages, 4 figures, 4 supplementary videos, supplementary information https://doi.org/10.1038/s41598-021-95729-6 ; Tsunamis are triggered by sudden seafloor displacements, and usually originate from seismic activity at faults. Nevertheless, strike-slip faults are usually disregarded as major triggers, as they are thought to be capable of generating only moderate seafloor deformation; accordingly, the tsunamigenic potential of the vertical throw at the tips of strike-slip faults is not thought to be significant. We found the active dextral NW–SE Averroes Fault in the central Alboran Sea (westernmost Mediterranean) has a historical vertical throw of up to 5.4 m at its northwestern tip corresponding to an earthquake of Mw 7.0. We modelled the tsunamigenic potential of this seafloor deformation by Tsunami-HySEA software using the Coulomb 3.3 code. Waves propagating on two main branches reach highly populated sectors of the Iberian coast with maximum arrival heights of 6 m within 21 and 35 min, which is too quick for current early-warning systems to operate successfully. These findings suggest that the tsunamigenic potential of strike-slip faults is more important than previously thought, and should be taken into account for the re-evaluation of tsunami early-warning systems ; This study was supported by the Spanish projects DAMAGE (CGL2016-80687-R AEI/FEDER), FAUCES (CTM2015-65461-C2-1-R), RNM148, B-RNM-301-UGR18 and AGORA P18-RT-3275 Junta de Andalucía. [.] Research partially funded by the Programa Operativo FEDER Andalucía 2014-2020, call made by the University of Jaén 2018. The ICM-CSIC authors acknowledge Severo Ochoa funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2019-000928-S) ; Peer reviewed

One of the most significant parameters for seismic hazard assessment analyses is the fault slip rate. The combination of both geological (long-term) and geodetic (short-term) data offers a more complete characterization of the seismic potential of active faults. Moreover, geodetic data are also a helpful tool for the analysis of geodynamic processes. In this work, we present the results of a local GPS network from the Baza sub-Basin (SE Spain). This network, which includes six sites, was established in 2008 and has been observed for seven years. For the first time, we obtain short-term slip rates for the two active faults in this area. For the normal Baza Fault, we estimate slip rates ranging between 0.3 ± 0.3 mm/yr and 1.3 ± 0.4 mm/yr. For the strike-slip Galera Fault, we quantify the slip rate as 0.5 ± 0.3 mm/yr. Our GPS study shows a discrepancy for the Baza Fault between the short-term slip rates and previously reported long-term rates. This discrepancy indicates that the fault could be presently in a period with a displacement rate higher than the mean of the magnitude 6 seismic cycle. Moreover, the velocity vectors that we obtained also show the regional tectonic significance of the Baza Fault, as this structure accommodates one-third of the regional extension of the Central Betic Cordillera. Our GPS-related slip rates form the basis for future seismic hazard analysis in this area. Our results have further implications, as they indicate that the Baza and Galera Faults are kinematically coherent and they divide the Baza sub-Basin into two tectonic blocks. This points to a likely physical link between the Baza and Galera Faults; hence, a potential complex rupture involving both faults should be considered in future seismic hazard assessment studies. ; We acknowledge the comments of Editor Prof. Irina M. Artemieva and two anonymous reviewers, which significantly improved the quality of this paper. This research was funded by the Spanish Ministry of Science, Innovation and University (Research Projects: RTI2018-100737-BI00 and CGL2016-80687-R), the University of Alicante (Research Project: VIGROB053), the University of Jaén (PAIUJA 2019-2020 and Programa Operativo FEDER Andalucía 2014-2020 - call made by UJA 2018), the University of Granada (B-RNM-301-UGR18) and the Junta de Andalucía regional government (RNM148, RNM282, and RNM370 and P18-RT-3275 research groups). We thank all observers who collected the data of survey-mode GPS measurements.

One of the most significant parameters for seismic hazard assessment analyses is the fault slip rate. The combination of both geological (long-term) and geodetic (short-term) data offers a more complete characterization of the seismic potential of active faults. Moreover, geodetic data are also a helpful tool for the analysis of geodynamic processes. In this work, we present the results of a local GPS network from the Baza sub-Basin (SE Spain). This network, which includes six sites, was established in 2008 and has been observed for seven years. For the first time, we obtain short-term slip rates for the two active faults in this area. For the normal Baza Fault, we estimate slip rates ranging between 0.3 ± 0.3 mm/yr and 1.3 ± 0.4 mm/yr. For the strike-slip Galera Fault, we quantify the slip rate as 0.5 ± 0.3 mm/yr. Our GPS study shows a discrepancy for the Baza Fault between the short-term slip rates and previously reported long-term rates. This discrepancy indicates that the fault could be presently in a period with a displacement rate higher than the mean of the magnitude 6 seismic cycle. Moreover, the velocity vectors that we obtained also show the regional tectonic significance of the Baza Fault, as this structure accommodates one-third of the regional extension of the Central Betic Cordillera. Our GPS-related slip rates form the basis for future seismic hazard analysis in this area. Our results have further implications, as they indicate that the Baza and Galera Faults are kinematically coherent and they divide the Baza sub-Basin into two tectonic blocks. This points to a likely physical link between the Baza and Galera Faults; hence, a potential complex rupture involving both faults should be considered in future seismic hazard assessment studies. ; This research was funded by the Spanish Ministry of Science, Innovation and University (Research Projects: RTI2018-100737-B-I00 and CGL2016-80687-R), the University of Alicante (Research Project: VIGROB053), the University of Jaén (PAIUJA 2019-2020 and Programa Operativo FEDER Andalucía 2014-2020 - call made by UJA 2018), the University of Granada (B-RNM-301-UGR18) and the Junta de Andalucía regional government (RNM148, RNM282, and RNM370 and P18-RT-3275 research groups).