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Mehr als verschüttete Täler: Dienen Tunneltäler als bevorzugte Fließwege für frisches Grundwasser in der Nordsee?

Die stetig wachsende Bevölkerung führt zu einem steigenden Bedarf an Frischwasser und die Entnahme von Grundwasser ist eine der wichtigsten Quellen diesen Bedarf zu decken. Engpässe in der Frischwasserversorgung haben die Suche Nachweis von frischem Grundwasser unter dem heutigen Meeresboden angetrieben. Die Rolle glazialer Strukturen, welche während der Vergletscherungen entstanden sind, ist jedoch im Hinblick auf das Vorkommen frischen Grundwassers noch wenig bekannt. Insbesondere sogenannte Tunneltäler (TT), welche sich unter den Eisschilden bildeten, könnten von besonderer Relevanz sein. Ihre Ausmaße (bis zu 5 km breit, 400 m tief, 100te km lang) spiegeln die gewaltigen Schmelzwassermengen wider, die den Untergrund unter den Eisschilden durchspülten. Ihre Entstehung und Füllung resultierte in stark durchlässigen Sanden und Kiesen im unteren Teil und feinkörnigen Ablagerungen im oberen Teil dieser Strukturen. Diese Konfiguration begünstigt eine Rolle als bevorzugte Fließwege für offshore Grundwasser. Zur Untersuchung des Potenzials von TT als bevorzugte Fließwege für offshore frisches Grundwasser (OFG), verfolgt dieses Projekt folgende Ziele: (O1) Durch die Kombination von elektromagnetischen und seismischen Daten wollen wir ein strukturgebundenes Widerstandsmodell für mehrere TT erstellen; (O2) Wir wollen die Salzgehaltswerte für verschiedene Architekturen und Tiefen von TT abschätzen; (O3) Aufbauend auf den ersten beiden Zielen wollen wir die Ergebnisse für das gesamte Arbeitsgebiet in ein detailliertes lithologisches 3D-Modell extrapolieren. Die sich daraus ergebende Salzgehaltsverteilung im Untergrund wird dazu beitragen, die Ober- und Untergrenzen des Volumens frischen Grundwassers abzugrenzen und die Grundlage für ein detailliertes Grundwassermodell schaffen. Folgende Schritte sind dazu nötig: (S1) Kartierung und Charakterisierung der räumlichen Heterogenität von TT anhand vorhandener seismischer Daten; (S2) Erstellung eines lithologischen Modells für den Untergrund zwischen Amrum und Helgoland von 0 bis 400 m Tiefe; (S3) Identifizierung vielversprechender Standorte und Durchführung von CSEM-Messungen (Controlled Source Electromagnetic) zur Untersuchung der Verteilung des elektrischen Widerstands im Untergrund (TT); (S4) Kombination von Widerstandsmessungen mit Mehrkanal-Seismikdaten (MCS) zur Ableitung des Salzgehalts der Porenflüssigkeit; (S5) Extrapolation der Ergebnisse für das gesamte lithologische Modell. Tunneltäler existieren in ehemals vergletscherten Regionen weltweit. Gelingt uns der Nachweis von OFG in Tunneltälern, hätte dies erhebliche Implikationen für bisher unbekannte Süßwasserverteilungen und hydrologische Systeme. Die uns zur Verfügung stehenden Daten bieten eine einzigartige Möglichkeit zur Integration von CSEM- und seismischen Messungen bei begrenztem Aufwand. Die Ergebnisse des Projekts werden einen neuen Blick auf offshore Gletscherlandschaften und ihre Rolle im pleistozänen Wasserkreislauf erlauben.

Infrasound array signal processing results of far-field stations for the Falcon 9 rocket stage re-entry over central Europe on 19 February 2025

Supplementary information to the manuscript “Seismoacoustic analysis of a Falcon 9 rocket stage re-entry over central Europe on 19 February 2025” by Hupe et al. (2026). Results of the Progressive Multi-Channel Correlation (PMCC) processing for far-field infrasound stations, displayed in Figure 7 of the manuscript (IS26 in Germany, NRSI in Norway, HFSI in Sweden). The netcdf files contain the following detection parameters of single arrivals: Time, duration, back-azimuth, apparent velocity, frequency, family identifier. Data format: One .nc file for each station.

Global reference histograms of the IMS infrasound broadband detection lists

This data set builds upon the broadband detection lists of the International Monitoring System (IMS)’s infrasound stations. The infrasound data of these stations are regularly (re-)processed at the German National Data Centre at BGR (e.g., Ceranna et al., 2019; https://doi.org/10.1007/978-3-319-75140-5_13) using the Progressive Multi-Channel Correlation (PMCC) array processing method (Cansi, 1995; https://doi.org/10.1029/95GL00468). The latest reprocessing with 26 one-third octave spaced frequency bands in the IMS band of interest (0.01 to 4 Hz) included all 53 stations that were certified within the period 2003 to 2020. Based on the resulting broadband detection lists, this data set expands on former analyses of the coherent ambient noise. For each station with a data availability of at least one year (by the end of 2020), monthly reference histograms for the detection parameters back azimuth, apparent speed, and root-mean-squared amplitude are provided. The histograms provide a means to determine the deviation from nominal monthly behaviour and thus enable assessing the plausibility of detections and potential anomalies – without determining their cause – in the detected parameters. Overall, these quality metrics will be, among other applications, a useful supplement to the open-access IMS infrasound data products provided by Hupe et al., which are also available in BGR’s product centre. Further details of the reference histograms are described in the following publication by Kristoffersen et al.: "Updated global reference models of broadband coherent infrasound signals for atmospheric studies and civilian applications" (https://doi.org/10.1029/2022EA002222).

Infrasonic Signatures of 1001 Rocket Launches for Space Missions

Rocket launches for space missions are well-defined ground-truth events generating strong infrasonic signatures. This data set covers ground-truth information for 1001 rocket launches from 27 global spaceports between 2009 and mid-2020. Infrasound signatures from up to 73% of the launches were identified at infrasound arrays of the International Monitoring System. The detection parameters were obtained using the Progressive Multi-Channel Correlation (PMCC) algorithm. Propagation and quality parameters supplement the PMCC detection parameters in this dataset. The results are provided for further use as a ground-truth reference in geophysical and atmospheric research. The open-access publication “1001 Rocket Launches for Space Missions and their Infrasonic Signature” (Pilger et al., 2021, Geophys. Res. Letters, doi:10.1029/2020GL092262) provides further details on this data set. Data format: The data are provided both as ASCII files (separate lists of infrasound signatures and rocket launch events, plus README files) and as a comprehensive netCDF file.

Processed seismic data of Cruise MSM14/2 2010

The initial study area of the cruise MSM14/2 GeoNORM (Geophysik im noerdlichen Roten Meer) was the northern Red Sea. However, because of not given research permissions from Egypt and Saudi Arabia, the study area had to be changed to the alternative study area Eratosthenes Seamount (ESM), south of Cyprus. The ESM is supposed to represent a continental fragment of the former African-Arabian Plate that is entering the subduction zone south of Cyprus i.e. the subduction turns into collision in the area of the ESM. This changed the entire tectonic setting in the Eastern Mediterranean. Therefore, the tectonic evolution of the area is rather complex with phases of extension, subduction, compression, salt tectonics and gravitational processes and not comprehensively understood. Because of the isolation of the ESM as a continental fragment this region is an ideal spot to investigate the transition from regular subduction to continental collision and its associated tectonic processes i.e. faults were activated or reactivated, transform motion has to be compensated, the overriding plate has been elevated. This impacts the ongoing geological and tectonic processes in this region but also influences the social and economic life in the Eastern Mediterranean as earthquakes and submarine landslides are possible geohazards and the entering of the ESM to the subduction trench alters the thermal history of the adjacent sedimentary basins significantly what should have an influence on the maturity processes within the source rock sediments and new faults open new migration paths for hydrocarbon fluids or gases.

Marine Seismic Survey Profiles (MSSP) (WMS)

During the period from 1974 to 2018 various cruises from BGR acquired seismic lines worldwide. The aim of these marine expeditions was a detailed survey of the geological structure.

INSPIRE ST GE-GP, Messgebiete, Messstationen

Datenebene enthält die Gebiete geophysikalischer Untersuchungen unterteilt in die einzelnen Messverfahren Geoelektrik, Geomagnetik, Gravimetrie, Seismik. Die Informationen zu den geophysikalischen Untersuchungen beinhalten Angaben zum Gebiet, Zeitraum der Messungen, Ergebnisberichte und Bezeichnungen der Ablage im Fachinformationssystem. Darüber hinaus enthält die Datenebene die Standorte der seismologischen Überwachung in Sachsen-Anhalt, Informationen zu den Stationen und der Überwachungsergebnisse. Messdaten sind nicht Bestandteil dieses Datensatzes.

Processed seismic data of Cruise BGR 1977

A geophysical reconnaissance survey was carried out in the Labrador Sea and Davis Strait between July and September 1977 by BGR. The data format is Society of Exploration Geophysicists SEG Y. The survey was executed on the research vessel MS Explora. The seismic, magnetic and gravity data from 5931 line-kilometers on 21 lines were recorded on magnetic tape. A 24-fold coverage technique was used with 48 seismic channels (traces), with a 2400m streamer cable, and 23.45 l airgun array. A full integrated computerized satellite navigation system (INDAS III) served as positioning system. Based on a preliminary interpretation of the seismograms, the Labrador Sea was devided into an eastern (Greenland) and western (Canadian) area, seperated by the Mid Labrador Ridge. Within the eastern part of the Labrador Sea the Pre-Cenozoic sediments show three distinct layers, traceable over the entire Greenland area of the sea. In the Cenozoic layer olisthostromes occur. The highest apparent velocity determined from sonobuoy data was 9.26 km/sec. The calculated refractor lies at a depth of approximately 13 km. The seismic section from the sediments on the Canadian side of the Labrador Sea show a uniform series of thick sediments below the Cenozoic cover. The highly disturbed basement is often masked by the multiple reflections from the seafloor. Statements about the nature and structure of the basement can only be made after processing data.

Processed seismic data of Cruise BGR13-2 2013 (PANORAMA-1)

The research cruise PANORAMA-1 onboard the Italian vessel OGS Explora was carried out within 2 legs in the period August, 16th – September 17th 2013. The designated survey area was located in a sector of the European Arctic north of Svalbard covering an area north of 80°N between 15°E and 35°E. Main objectives were to acquire new geophysical data and extract near surface sediment samples in an underexplored area of the European Arctic with special focus on the transition zone from the North Barents shelf towards the oceanic Nansen basin. During leg 1 of the cruise a 20 days geophysical survey 1056 km of multi-channel seismic data was acquired supplemented by a 221 km long sonobuoy profile. Additionally, magnetic and sediment echosounding data was acquired along these profiles. During all operations within the survey area gravity and multibeam echosounding data was continuously acquired. After a 1 day stopover in Longyearbyen in order to exchange part of the scientific crew OGS Explora returned to the survey area to continue survey operations during leg 2. Within these 10 days period near surface sediments were extracted by means of a gravity corer at 12 locations and heat flow soundings were conducted at 7 locations. Gravity, sediment and multibeam echosounding data was continuously acquired along all transit lines within the survey area during leg 2. Total line length of magnetic data was 2658.7 km. Over all track lines with bathymetric and gravity data amount to 5665.8 km in total.

Processed seismic data of Cruise BGR 1994

On the M/V Akademic Nemchinow multichannel seismic measurements were carried out on 34 lines with a total length of 4,000 km. The area covered was the Laptev Sea. The data format is Society of Exploration Geophysicists SEG Y.

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