Electromagnetic IMAGINING of deep SUBMARINE freshwater

This research harness a joint-interpretation approach, using a surface-towed controlled-source electromagnetic (CSEM) system in conjunction with high-resolution multi-beam for seafloor mapping and water column scanning for 2-D resistivity and 3-D magnetic imaging of deep submarine groundwater deposits offshore Hawai'i volcanic islands. This study reveals a novel onshore to offshore transport mechanism of freshwater in Hawai'i (Attias et al., 2020), most likely the governing mechanism in other volcanic islands worldwide. The CSEM inversion also imaged multiple large-scale freshwater plumes extending from the seafloor to the ocean surface (Attias et al., 2021). This experiment offers an effective method to elucidate hydrogeologic and ocean processes that affect biogeochemical cycles in coastal waters worldwide.

Visualization of seafloor-to-ocean surface freshwater plumes offshore Hawai'i.

This marine CSEM project used a newly developed surface-towed marine electromagnetic Porpoise CSEM array system owned by the Scripps Institution of Oceanography EM laboratory. 2-D CSEM inversion algorithm been implemented to image and characterize the spatial distribution, interconnectivity, and transport mechanism of freshwater from the coastal aquifer to offshore Hawai‘i via a deep submarine groundwater multilayer system. Link to the project website: IkeWai Marine CSEM

Schematic illustration of the Porpoise surface-towed CSEM system. The system includes a 40 m horizontal electric dipole (HED) source that emits a current of 100 amps, and 4 Porpoise receivers (with 2 m inline electric dipole, data logger, GPS) at in… — Schematic illustration of the Porpoise surface-towed CSEM system. The system includes a 40 m horizontal electric dipole (HED) source that emits a current of 100 amps, and 4 Porpoise receivers (with 2 m inline electric dipole, data logger, GPS) at increment distance ~250 m to form a 1 km array.

The marine CSEM survey layout: The red lines denote the parallel survey towlines, whereas the black lines represent the survey crosslines. Right inset: Bathymetry/elevation map of the island of Hawaiʻi. The survey area is indicated by black rectangu… — The marine CSEM survey layout: The red lines denote the parallel survey towlines, whereas the black lines represent the survey crosslines. Right inset: Bathymetry/elevation map of the island of Hawaiʻi. The survey area is indicated by black rectangular.

***Porpoise array alignment along crossline 1. Our chase boat is positioned at the end of the 1 km array of Porpoise E-field receivers.***

Power spectrograms showing the E-Field signal as recorded by each one of the Porpoises in days 4 and 5 of the survey. Note the decade in the signal as a function of the offset from the CSEM transmitter and transmitted Amps. The distinctive bands rep… — Power spectrograms showing the E-Field signal as recorded by each one of the Porpoises in days 4 and 5 of the survey. Note the decade in the signal as a function of the offset from the CSEM transmitter and transmitted Amps. The distinctive bands represent the strongest harmonics of waveform-D (3 Hz, 7 Hz, 13 Hz) that is used in this survey.

Time-lapse of surfaced-towed CSEM, Multi-Beam, and Sound Velocity Profile Instruments Recovery.

GAS HYDRATE imaging offshore NORWAY

For this project I developed a robust controlled-source electromagnetic (CSEM)-seismic-rock physics joint-interpretation scheme; for the detection, delineation, and quantification of sub-seafloor gas hydrate structures, Off shore Norway (Attias et al., 2016). For this purpose, I processed, analyzed and interpreted separately and jointly three datasets: CSEM, seismic and sediment cores datasets (Attias et al., 2018). These datasets are compared with SCA/DEM effective medium models to derive a robust estimation of gas hydrate saturation (Attias et al., 2020).

Marine CSEM system that includes a deep-towed electromagnetic transmitter, seafloor, and a towed receivers.

BLACKSMITH & KAJIYA: gas hydrate exploration in japan

Marine EM geophysicist consultant for Ocean Floor Geophysics. The project involved the operation of a CSEM array, acquisition, and processing of large dataset, to yield a high-resolution imaging of three
gas hydrate fields, Offshore Japan. The data were acquired by a towed CSEM system, employing the Vulcan instrument that was developed by the Scripps Institution of Oceanography. Project link

BLUEMINING: seafloor massive sulfide RESEARCH

This project characterize seafloor massive sulfide (SMS) accumulations at extinct hydrothermal systems at the vicinity of the active TAG hydrothermal vent. In this project, I aided in designing the CSEM survey (pre-survey synthetic modeling), operated the University of Southampton CSEM deep-towed system, processed the preliminary data, and generated on-site pseudosections. I also assisted in performing 2-D CSEM inversion (Haroon et al., 2018), demonstrating the effect of fluctuated 3-D bathymetry on 2-D modeling. This study provides significant evidence for SMS deposits at these extinct hydrothermal systems. Project link

Blue Mining Project Research Cruise: The Blue Mining project is an international European consortium of 19 large industry and research organisations on various maritime fields of expertise, the "Blue Mining" consortium, will develop solutions that will bring sustainable deep sea mining a big step closer.