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.

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.

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