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  • 1
    Publication Date: 2020-08-05
    Description: Agadir Canyon is one of the largest submarine canyons in the World, supplying giant submarine sediment gravity flows to the Agadir Basin and the wider Moroccan Turbidite System. While the Moroccan Turbidite System is extremely well investigated, almost no data from the source region, i.e. the Agadir Canyon, are available. Understanding why some submarine landslides remain as coherent blocks of sediment throughout their passage downslope, while others mix and disintegrate almost immediately after initial failure, is a major scientific challenge, which was addressed in the Agadir Canyon source region during Cruise MSM32. We collected ~ 1500 km of seismic 2D-lines in combination with a dense net of hydroacoustic data. About 1000 km2 of sea floor were imaged during three deployments of TOBI (deep-towed sidescan sonar operated by the National Oceanography Centre Southampton). A total of 186 m of gravity cores and several giant box cores were recovered at more than 50 stations. CTD casts were collected at nine stations including one 13 hour Yo-yo CTD. The new data show that Agadir canyon is the source area of the world's largest submarine sediment flow, which occurred about 60,000 years ago. Up to 160 km3 of sediment was transported to the deep ocean in a single catastrophic event. For the first time, sediment flows of this scale have been tracked along their entire flow pathway. A major landslide area was identified south of Agadir Canyon. Landslide material enters Agadir canyon in about 2500 m water depth; the material is transported as debrite for at least another 200 km down the canyon. Initial data suggest that the last major slide from this source entered Agadir canyon at least 130,000 years ago. Living deep-water corals were recovered from a large mound field north of Agadir canyon. To our knowledge, these are the first living cold water corals recovered off the coast of Morocco (except for the Gulf of Cadiz). They represent an important link between the known cold-water coral provinces off Mauritania and in the Gulf of Cádiz.
    Type: Report , NonPeerReviewed
    Format: text
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  • 2
    Publication Date: 2021-05-11
    Description: Summary The continental margins of southern Italy are located along converging plate boundaries, which are affected by intense seismicity and volcanic activity. Most of the coastal areas experienced severe earthquakes, landslides, and tsunamis in historical and/or modern times. The most prominent example is the Messina earthquake of Dec. 28, 1908 (Ms=7.3; 80,000 casualties), which was characterized by the worst tsunami Italy experienced in the historical time (~2000 casualties). It is, however, still unclear, whether this tsunami was triggered by a sudden vertical movement along a major fault during the earthquake or as a result of a giant marine slide initiated by the earthquake. The recurrence rates of major landslides and therefore the risk associated with landslides is also unknown. Based on detailed bathymetric data sets collected by Italian colleagues in the frame of the MaGIC Project (Marine Geohazards along the Italian Coast), we collected seismic data (2D and 3D) and gravity cores in three working areas (The Messina Straits, off Eastern Sicily, the Gioia Basin). A dense grid of new 2D-seismic data in the Messina Straits will allow to map fault patterns in great detail. One interesting outcome in this context is the identification of a set of normal faults striking in an EW-direction, which is almost perpendicular to the previously postulated faults. This EW-striking faults seem to be active. The area off eastern Sicily is characterized by numerous landslides and a complex deformation pattern. A 3D-seismic data set has been collected during the cruise using the so called P-cable in order to investigate these deformation patterns in detail. The new data will be the basis for a risk assessment in the working areas.
    Type: Report , NonPeerReviewed
    Format: text
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  • 3
    Publication Date: 2023-11-24
    Description: ALKOR cruise AL600 served as a marine geophysical field course for ‘Physics of the Earth System’ bachelor students at Kiel University. Beside taking an active role in planning and realization of the individual geophysical measurements, the students also performed some first processing and interpretation of the obtained data. This work had to be documented in form of a scientific presentation as well as writing of the respective chapter in this cruise report. For the following chapters, we (Sebastian Krastel, Jens Schneider von Deimling) decided to only slightly modify the text and figures provided by the students. This should emphasize the student’s achievements, and underline the overarching aim of the cruise to train the students in acquisition, processing, and documentation of marine geophysical data.
    Type: Report , NonPeerReviewed
    Format: text
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  • 4
    Publication Date: 2023-07-12
    Description: Research cruise AL579 is part of the bachelor course "Physics of the Earth System - Geophysics, Meteorology and Oceanography" at the University of Kiel. It is the field exercise for marine geophysics and hydroacoustics. The aim of the annually recurring cruise is to give students a practical insight into the acquisition, processing, documentation, and interpretation of marine geophysical data. AL579 took place from August 20th -28th 2022 with the main study areas in Eckernförde Bay and the Bay of Mecklenburg. Parts of the scientific crew changed during a stopover in Kiel on Wednesday, 24.8.2022. In Eckernförde Bay we mainly collected Multibeam Echosounder (MBES) and INNOMAR Subbottom Echosounder (SES) data calibrated by CTD measurements close to the pockmark field off Mittelgrund. On Wednesday, 24.8.2022 we tested a new Ocean Bottom Seismometer (OBS) prototype. In the Bay of Mecklenburg, the focus was on Blinkerhügel and the seafloor structures further west where an enigmatic stone structure was discovered in 2021. This area was surveyed with Sidescan Sonar, MBES, SES, and CTD measurements and several video transects with an underwater drone. We also collected two sets of multi-channel seismic data to investigate the deeper structures of the Western Baltic Sea and the Bay of Mecklenburg.
    Type: Report , NonPeerReviewed
    Format: text
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  • 5
    Publication Date: 2022-03-07
    Description: Coastal and ocean island volcanoes are renowned for having unstable flanks. This can lead to flank deformation on a variety of temporal and spatial scales ranging from slow creep to catastrophic sector collapse. A large section of these unstable flanks is often below sea level, where information on the volcano-tectonic structure and ground deformation is limited. Consequently, kinematic models that attempt to explain measured ground deformation onshore associated with flank instability are poorly constrained in the offshore area. Here, we attempt to determine the locations and the morpho-tectonic structures of the boundaries of the submerged unstable southeastern flank of Mount Etna (Italy). The integration of new marine data (bathymetry, microbathymetry, offshore seismicity, reflection seismic lines) and published marine data (bathymetry, seafloor geodesy, reflection seismic lines) allows identifying the lineament north of Catania Canyon as the southern lateral boundary with a high level of confidence. The northern and the distal (seaward) boundaries are less clear because no microbathymetric or seafloor geodetic data are available. Hypotheses for their locations are presented. Geophysical imaging suggests that the offshore Timpe Fault System is a shallow second-order structure that likely results from extensional deformation within the moving flank. Evidence for active uplift and compression upslope of the amphitheater-shaped depression from seismic data along with subsidence of the onshore Giarre Wedge block observed in ground deformation data leads us to propose that this block is a rotational slump, which moves on top of the large-scale instability. The new shoreline-crossing structural assessment may now inform and improve kinematic models.
    Description: Published
    Description: 810790
    Description: 2V. Struttura e sistema di alimentazione dei vulcani
    Description: JCR Journal
    Keywords: seafloor ; fault ; flank dynamics ; hydroacoustic ; geodesy ; seismic profiles ; 04.07. Tectonophysics ; 04.08. Volcanology ; 04.06. Seismology ; 04.02. Exploration geophysics ; 05.02. Data dissemination
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 6
    Publication Date: 2022-02-14
    Description: Marine seismic reflection data coupled with on-land structural measurements improve our knowledge about the active deformation pattern of the northern sector of the Malta Escarpment, a bathymetric and structural discontinuity in the near-offshore of Eastern Sicily. As favourably oriented to be reactivated within the Neogene Africa–Europe convergence, it is believed that the Malta Escarpment has a significant role in the recent seismotectonic framework of the Western Ionian Basin and the Hyblean foreland domain of SE Sicily, where some of the largest and most destructive Mediterranean earthquakes are located according to available historical catalogs. Offshore seismic data along with bathymetric grids illuminate the shallow subseafloor setting and allow more accurate mapping of the seafloor expression of previously identified faults in the area. The seismic interpretation and the nearfault sediment pattern analysis provide constraints on fault 3D geometries as well as on their through-time tectonic activity, suggesting also that part of the observed deformation may have been caused by nontectonic processes. Identified faults form currently an E-dipping, roughly N–S trending, and 60 km-long extensional belt deforming the seafloor with a significant displacement amount in the Ionian offshore between Catania and Siracusa. 3-dimensional parameters of faults were then used to derive expected magnitudes and their reactivation propensity. Empirical scaling relationships and forward methods point to a high seismic potential for the detected fault as well as predict the fault slip behavior according to the fieldderived differential stress. This combined analysis along with faults displacement measurements pointed out how the longest and most continuous fault could be capable of generating M 〉 7 seismic events, putting forward strong seismotectonic implications for the adjacent and densely populated Hyblean Plateau. The expected magnitude and the estimated recurrence time interval are compatible with those inferred for large historical earthquakes in the area even if other offshore seismic sources cannot be ruled out.
    Description: Published
    Description: 594176
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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  • 7
    Publication Date: 2023-03-27
    Description: Argnani (2021) provides a commentary (hereafter ARGN) on our paper titled: “Deformation Pattern of the Northern Sector of the Malta Escarpment: Fault Dimension, Slip Prediction, and Seismotectonic Implications,” which was published in the journal Frontiers in Earth Science in January 2021 (Gambino et al., 2021, hereafter GAMB). Through the interpretation of eight new seismic profiles (six of which are reported in Supplementary Figure S1 of GAMB) crossing the Malta Escarpment, GAMB pointed to a better definition of the geometry of three active faults (F1, F2, F3) and their seismic potential by employing slip tendency modeling and forward analysis. The results suggest that F3 is prone to be reactivated under the achieved stress field and has the capacity of generating M 〉 7 earthquakes. ARGN raises concerns about the higher resolution and less penetration of the eight newly acquired high-resolution multichannel reflection seismic profiles and the seismic-stratigraphic pattern proposed by GAMB. According to ARGN, “the seismic profiles analyzed by GAMB belong to different sets and have very different seismic characters and resolution, making seismic facies correlation pretty difficult, also because no tie lines are available. As a result, stratigraphic correlations are highly speculative and the ensuing uncertainties undermine the timing of the tectonic evolution envisaged by GAMB, as well as the age and rate of activity of tectonic structures.” Furthermore, ARGN argues on the hypothesis of an early large-scale slope instability affecting the area. Most of the statements of ARGN seem to be based on his available older multichannel reflection seismic profiles, which have, indeed, a higher penetration but less resolution. We also agree that high-resolution digital multichannel seismic profiles are not easily comparable with low-resolution multichannel seismic lines, but we see the clear advantage of a state-of-the-art technology to image the upper strata of sedimentary systems. The used system proved its robustness in many different settings worldwide and has been successfully used for many pre-site surveys for drilling campaigns for the IODP and ICDP. As a result, we rebut point-by-point ARGN’s comments and stand by our model on the active deformation pattern and seismotectonics of the northern sector of the Malta Escarpment.
    Description: Published
    Description: 886439
    Description: 2T. Deformazione crostale attiva
    Description: JCR Journal
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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