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  1. AU="Weckmann, U."
  2. AU="Martínez-Sáez, O"
  3. AU="dos Santos, Alejandra Filippo Gonzalez Neves"
  4. AU="Beverly Castillo Herrera"
  5. AU="Fatin Izzati Abdul Hadi"
  6. AU="Musinguzi, Nicholas"
  7. AU=Lee Edward Y
  8. AU="Raval, Urdhva"
  9. AU="Senn, L Kirsten"
  10. AU="Matsutani, Noriyuki"
  11. AU="Bernstein, Herbert J"
  12. AU="Elisa Impresari"
  13. AU="Feldman, Noa"
  14. AU="Dhingra, Mandeep Singh"

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  1. Artikel ; Online: Magnetotelluric images of the medium enthalpy Bakreswar geothermal province within a granitic gneissic complex, Eastern Indian Peninsula

    Singh, R. / Weckmann, U. / Srivastava, S.

    Geophysical Prospecting

    2023  

    Abstract: The Bakreswar geothermal province represents a medium enthalpy geothermal system with its Bakreswar and Tantloie hot springs. It lies within the Chotanagpur Granite Gneissic Complex in the eastern part of the Indian Peninsula. The province has a high ... ...

    Abstract The Bakreswar geothermal province represents a medium enthalpy geothermal system with its Bakreswar and Tantloie hot springs. It lies within the Chotanagpur Granite Gneissic Complex in the eastern part of the Indian Peninsula. The province has a high heat flow and a high geothermal gradient of 90°C/km. Magnetotelluric data from 95 sites in a frequency range of 10 kHz–10 Hz were acquired over the Bakreswar geothermal province to obtain an electrical conductivity model and map the geothermal reservoir with its fluid pathways and related geological structures. Subsurface conductivity models obtained from three-dimensional inversions of the Magnetotelluric data exhibit several prominent anomalies, which are supplemented by gravity results. The conductivity model maps three features which act as a conduit (a) a northwest–southeast trending feature, (b) an east–west trending feature to the south of the northwest–southeast trending feature (which lies 1 km north of the Oil and Natural Gas Corporation fault marked by previous studies) and (c) shallow conducting features close to Bakreswar hot spring. The northwest–southeast trending feature coincides with the boundary of the high-density intrusive block. This northwest–southeast trending feature provides the pathway for the meteoric water to reach a maximum depth of 2.7 km, where it gets heated by interacting with deep-seated structures and then it rises towards the surface. The radiogenic process occurring within the granites of Chotanagpur Granite Gneissic Complex provides the heat responsible for heating the meteoric water. The northwest–southeast and east–west trending features are responsible for the transport of meteoric water to deeper depths and then towards the shallow regions of the Earth. The near surface features close to the Bakreswar hot spring are responsible for carrying the water further towards the hot spring. The resistivity of these structures plotted as a function of salinity and temperatures for saline crustal fluids suggests the involvement of ...
    Thema/Rubrik (Code) 550
    Erscheinungsdatum 2023-11-05
    Erscheinungsland de
    Dokumenttyp Artikel ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  2. Buch ; Online: Die elektrische Leitfähigkeit von fossilen Störungszonen und Mobile Belts

    Weckmann, U.

    2016  

    Sprache Deutsch
    Verlag Universität Potsdam
    Erscheinungsland de
    Dokumenttyp Buch ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  3. Buch ; Artikel ; Online: Site characterization of the PIER-ICDP drill holes by imaging the subsurface electrical conductivity structure

    Weckmann, U. / Platz, A.

    local and regional structure beneath Mýtina and Neualbenreuth Maar (ConeEM)

    2020  

    Abstract: The West Bohemian Massif as part of the geodynamically active European Cenozoic Rift System is characterised by ongoing magmatic processes in the intra-continental lithospheric mantle. A series of phenomena such as massive degassing of CO2 and repeated ... ...

    Abstract The West Bohemian Massif as part of the geodynamically active European Cenozoic Rift System is characterised by ongoing magmatic processes in the intra-continental lithospheric mantle. A series of phenomena such as massive degassing of CO2 and repeated earthquake swarms make the Eger Rift a unique target area for European intra-continental geo-scientific research. The ICDP project "Drilling the Eger Rift" was funded to study the field of earthquake-fluid-rock-biosphere interaction. In the framework of this ICDP project, magnetotelluric (MT) experiments have been conducted to image the subsurface distribution of the electrical conductivity down to depths of several tens of kilometres as the electrical conductivity is particularly sensitive to the presence of high-conductive phases such as aqueous fluids, partial melts or metallic compounds. Based on recent MT experiments in 2015/2016, Munoz et al. (2018) presented 2D images of the electrical conductivity structure along a NS profile across the Eger Rift. It reveals a conductive channel at the earthquake swarm region that extend from the lower crust to the surface forming a pathway for fluids up to the region of the mofettes. A second conductive channel is present in the south of the model. Due to the given station setup along a profile, the resulting 2D inversion allows ambiguous interpretations of this feature. As 3D inversion is required to distinguish between the different interpretations, we conducted another MT field experiment at the end of 2018. This data publication (10.5880/GIPP-MT. 201810 .1) encompasses a detailed report in pdf format with a description of the project, information on the experimental setup, data collection, instrumentation used, recording configuration and data quality. The folder structure and content of the data repository are described in detail in Ritter et al. (2019). Time-series data are provided in EMERALD format (Ritter et al., 2015).
    Thema/Rubrik (Code) 550
    Sprache Englisch
    Verlag GFZ Data Services
    Erscheinungsland de
    Dokumenttyp Buch ; Artikel ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  4. Artikel ; Online: An automated new pre-selection tool for noisy Magnetotelluric data using the Mahalanobis distance and magnetic field constraints

    Platz, A. / Weckmann, U.

    Geophysical Journal International

    2019  

    Abstract: In Magnetotellurics (MT) natural electromagnetic field variations are recorded to study the electrical conductivity structure of the subsurface. Thereby long time-series of electromagnetic data are subdivided into smaller segments, which are Fourier ... ...

    Abstract In Magnetotellurics (MT) natural electromagnetic field variations are recorded to study the electrical conductivity structure of the subsurface. Thereby long time-series of electromagnetic data are subdivided into smaller segments, which are Fourier transformed and typically averaged in a statistically robust manner to obtain MT transfer functions. Unfortunately, nowadays the presence of man-made electromagnetic noise sources often deteriorates a significant fraction of the recorded time-series by overprinting the desired natural field variations. Available approaches to obtain undisturbed and high quality MT results include, for example robust statistics, remote reference or multi-station analyses which aim at the removal of outliers or uncorrelated noise. However, we have observed that intermittent noise often affects a certain time span resulting in a second cluster of transfer functions in addition to the expected true MT distribution. In this paper, we present a novel criterion for the detection and pre-selection of EM noise in form of outliers or additional clusters based on a distance measure of each data segment with regard to the centre of the data distribution. For this purpose, we utilize the Mahalanobis distance (MD) which computes the distance between two multivariate points considering the covariance matrix of the data that quantifies the shape and the size of multivariate data distributions. As the MD considers the covariance matrix, it corrects not only for different variances but also for any correlation between the data. The computation of both, the mean value and covariance matrix, is susceptible to ouliers (e.g. noise) and requires a statistically robust estimation. We tested several robust estimators, for example median absolute deviation or minimum covariance determinant algorithm and finally implemented an automatic criterion using a deterministic minimum covariance determinant algorithm. We will present results using MT data from various field experiments all over the world, which illustrate successfull data improvement. This approach is able to remove scattered data points as well as to reject complete data cluster originating from noise sources. However, like all purely statistical algorithms the criterion is limited to cases where the majority of the recorded data is well-behaved, that is noise content is below 50 per cent. If the majority of data points originates from noise sources, the new criterion will fail if used in an automatic way. In these cases, additional input by the user either manually or in an automated fashion can be utilized. We therefore suggest to use an add-on criterion to back the MD selection and subsequent robust stacking in form of a physically motivated constraint based on the magnetic incidence direction. This property indicates whether the magnetic field originates from various sources in the far field or from a strong and well defined source in the near field.
    Thema/Rubrik (Code) 519
    Erscheinungsland de
    Dokumenttyp Artikel ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  5. Artikel ; Online: Electromagnetic and Magnetotelluric Measurements

    Weckmann, U. / Ritter, O.

    Geomagnetism, Aeronomy and Space Weather : A Journey from the Earth's Core to the Sun ; Special Publications of the International Union of Geodesy and Geophysics

    2019  

    Erscheinungsland de
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    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  6. Konferenzbeitrag ; Online: The grounding zone of the Ekström Ice Shelf, East Antarctica – Geophysical characterization using GNSS, seismology and magnetotellurics

    Fromm, T. / Ritter, O. / Weckmann, U. / Heidrich-Meisner, K. / Scheinert, M. / Fofonova, V.

    XXVIII General Assembly of the International Union of Geodesy and Geophysics (IUGG)

    2023  

    Abstract: Antarctica’s ice shelves are a highly critical component for the interlinkage between ice sheet and ocean. Their shape and evolution play an important role for the strength of ice mass loss, e.g. by amplification or weakening of the buttressing effect. ... ...

    Abstract Antarctica’s ice shelves are a highly critical component for the interlinkage between ice sheet and ocean. Their shape and evolution play an important role for the strength of ice mass loss, e.g. by amplification or weakening of the buttressing effect. Ocean tides are the most important direct forces acting on the ice shelves, inducing vertical and horizontal motion and deformation. In our study we investigate the effect of ocean tides on the Ekström Ice Shelf. The northward flow of the ice is mainly modulated by the tidal constituents at the ter-diurnal and quarter-diurnal bands, whereas the dominant vertical tides have a diurnal and semi-diurnal periodicity and amplitudes up to ten times larger than the ter- and quarter-diurnal tides. The causes of the higher frequency tidal modulations are still poorly understood. The area of the largest effect of the higher frequency tides is assumed to be the grounding zone of the ice streams feeding the ice shelf. Here we present first results of geophysical experiments at the grounding zone of the Ekström Ice Shelf conducted in the field seasons 2021/2022 and 2022/2023. In 2021/2022 we setup GNSS and seismic stations to record vertical and horizontal motion of the ice as well as seismic events in order to gain insights into ice dynamics and ground properties. In season 2022/2023 GNSS and seismic station were dismantled, and the experiments were complemented by magnetotelluric measurements to image the sub-ice ocean-land transition and the crustal structure beneath the ice stream.
    Thema/Rubrik (Code) 290
    Sprache Englisch
    Erscheinungsland de
    Dokumenttyp Konferenzbeitrag ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  7. Artikel ; Online: Making and Breaking of a Continent

    Weckmann, U.

    Surveys in Geophysics

    Following the Scent of Geodynamic Imprints on the African Continent Using Electromagnetics

    2012  

    Schlagwörter 550 - Earth sciences
    Erscheinungsland de
    Dokumenttyp Artikel ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  8. Buch ; Artikel ; Online: Mapping of the Whitehill Formation in the Eastern Karoo Basin near Jansenville

    Weckmann, U. / Platz, A. / Doucouré, M.

    2020  

    Abstract: The South African Karoo Basin, which is known for its potentially shale gas bearing formations, was the target of an extensive research programme launched by the Nelson Mandela University, South Africa. The aim of this project was to obtain a fundamental ...

    Abstract The South African Karoo Basin, which is known for its potentially shale gas bearing formations, was the target of an extensive research programme launched by the Nelson Mandela University, South Africa. The aim of this project was to obtain a fundamental understanding of the geology, petrology and hydrology of the sedimentary layers. In 2014, Magnetotelluric (MT) measurements were conducted in the Eastern Karoo Basin to image the electrical conductivity structure of the shallow subsurface and to develop a three-dimensional (3D) model. Previous studies by Weckmann et al. (2007a, b) and Branch et al. (2007) identified the potentially shale gas bearing Whitehill Formation as an electrically conductive sub-horizontal layer, which covers large parts of the Karoo Basin. The increased interest in future shale gas exploration raised concerns regarding the potential impact on aquifers in this water scarce and fragile environment. Since the electrical conductivity is sensitive to fluids, imaging both, the black shale horizon and the deep aquifer system in this region was the ultimate goal of the MT study. Our field experiment is designed to serve as a baseline study before any activity regarding shale gas exploitation commenced. With high resolution 2D and regional 3D inversion and forward models several aquifers, the Whitehill formation and the possible source region of the Beattie Magnetic Anomaly could be mapped.This data publication (10.5880/GIPP-MT.201423.1) encompasses a detailed report in pdf format with a description of the project, information on the experimental setup, data collection, instrumentation used, recording configuration and data quality. The folder structure and content of the data repository are described in detail in Ritter et al. (2019). Time-series data are provided in EMERALD format (Ritter et al., 2015).
    Thema/Rubrik (Code) 550
    Sprache Englisch
    Verlag GFZ Data Services
    Erscheinungsland de
    Dokumenttyp Buch ; Artikel ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  9. Buch ; Artikel ; Online: MT_ANT2

    Ritter, O. / Fromm, T. / Weckmann, U.

    GFZ Data Services

    magnetotelluric measurements around Neumayer Station III, Antarctica

    2020  

    Abstract: Magnetotellurics (MT) is a geophysical deep sounding tool that can help decipher the deep hydrology and geology of Antarctica, in concert with more established and already applied geophysical methods, such as seismology, gravity, and magnetics. ... ...

    Abstract Magnetotellurics (MT) is a geophysical deep sounding tool that can help decipher the deep hydrology and geology of Antarctica, in concert with more established and already applied geophysical methods, such as seismology, gravity, and magnetics. Electrical conductivity is an important physical parameter to identify properties of rocks and, perhaps more importantly, constituents within, such as fluids or mineralisation. The unique conditions of Antarctica, which is largely covered with ice cause technical issues, particularly with the electric field recordings, as highly resistive snow and ice at surface of Antarctica hampers contact of the E-field sensors (telluric electrodes) with the ground. The project was a feasibility study to address this principal problem and to test modified MT equipment of the Geophysical Instrument Pool Potsdam (GIPP) in the vicinity of the Neumayer Station III (NMIII) on the Ekström Ice Shelfon. This data publication encompasses a detailed report in .pdf format with a description of the project, information on the experimental setup, data collection, instrumentation used, recording configuration and data quality. The folder structure and content of the data repository are described in detail in Ritter et al. (2019). Time-series data are provided in EMERALD format (Ritter et al., 2015).
    Thema/Rubrik (Code) 550
    Sprache Englisch
    Verlag GFZ Data Services
    Erscheinungsland de
    Dokumenttyp Buch ; Artikel ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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  10. Artikel ; Online: 3D imaging of the subsurface electrical resistivity structure in West Bohemia/Upper Palatinate covering mofettes and Quaternary volcanic structures by using Magnetotellurics

    Platz, A. / Weckmann, U. / Pek, J. / Kováčiková, S. / Klanica, R. / Mair, J. / Aleid, B.

    Tectonophysics

    2022  

    Abstract: The region of West Bohemia and Upper Palatinate belongs to the West Bohemian Massif. The study area is situated at the junction of three different Variscan tectonic units and hosts the ENE-WSW trending Ohře Rift as well as many different fault systems. ... ...

    Abstract The region of West Bohemia and Upper Palatinate belongs to the West Bohemian Massif. The study area is situated at the junction of three different Variscan tectonic units and hosts the ENE-WSW trending Ohře Rift as well as many different fault systems. The entire region is characterized by ongoing magmatic processes in the intra-continental lithospheric mantle expressed by a series of phenomena, including e.g. the occurrence of repeated earthquake swarms and massive degassing of mantle derived CO2 in form of mineral springs and mofettes. Ongoing active tectonics is mainly manifested by Cenozoic volcanism represented by different Quaternary volcanic structures. All these phenomena make the Ohře Rift a unique target area for European intra-continental geo-scientific research. With magnetotelluric (MT) measurements we image the subsurface distribution of the electrical resistivity and map possible fluid pathways. Two-dimensional (2D) inversion results by Muñoz et al. (2018) reveal a conductive channel in the vicinity of the earthquake swarm region that extends from the lower crust to the surface forming a pathway for fluids into the region of the mofettes. A second conductive channel is present in the south of their model; however, their 2D inversions allow ambiguous interpretations of this feature. Therefore, we conducted a large 3D MT field experiment extending the study area towards the south. The 3D inversion result matches well with the known geology imaging different fluid/magma reservoirs at crust-mantle depth and mapping possible fluid pathways from the reservoirs to the surface feeding known mofettes and spas. A comparison of 3D and 2D inversion results suggests that the 2D inversion results are considerably characterized by 3D and off-profile structures. In this context, the new results advocate for the swarm earthquakes being located in the resistive host rock surrounding the conductive channels; a finding in line with observations e.g. at the San Andreas Fault, California.
    Thema/Rubrik (Code) 550
    Sprache Englisch
    Erscheinungsland de
    Dokumenttyp Artikel ; Online
    Datenquelle BASE - Bielefeld Academic Search Engine (Lebenswissenschaftliche Auswahl)

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