Marine controlled-source electromagnetic survey for deep imaging of submarine groundwater systems
The results of the IkeWai marine CSEM project were presented for the first time at AGU Annual Fall Meeting that was held in San Fransico this year. The results include 2-D CSEM isotropic/anisotropic inversions and magnetic data that image the electrical resistivity and magnetic signature of submarine groundwater structures extending up to ~4 km offshore. Our poster attracted attention from Earth scientists and hydrologists.
“Ocean sensors help UH researchers understand Hawaiʻi Island aquifers”
Read this article in the following link:
https://www.hawaii.edu/news/2019/04/09/ocean-sensors-hawaii-island-aquifers/
The backbone of the surface-towed CSEM system used in this survey are the Porpoise electric field receivers. We used a 1 km array with 4 Porpoises; each named after a fish that starts with the letter P: Parrotfish, Pike, Pompano, and Perch.
The packing & demobilization of the CSEM system took us 6 hours, primarily because of the extreme heat at the honokohau harbor.
With the help of Max, Brenden, Khaira and Keven, we got the CSEM system all packed before sunest, and even managed to celebrate the succesful completion of the survey at “the bar without a Poproise”.
Thank you all for following our survey blog!
Cheers,
Eric & the Survey Team
Our last day of operation was dedicated for surveying 3 crosslines (perpendicular to the Kona coastline) situated in the northern section of the survey area, inline with the offshore trajectories of the Kiholo Bay and the Hualalai volcano. These crosslines will help us to (a) validate the data acquired from 7 inlines in this area, and (b) detect any localized submarine lava tubes that extend offshore from the Hualalai volcano.
This completes our successful survey! where we collected multiple datasets from ~250 km of towlines (total of 15 survey lines) encompassed within the boundaries of the Hualalai aquifer. This data will be utilized to detect, delineate, and understand both the spatial distribution and interconnectivity of deep submarine groundwater deposits, offshore Kona, the Island of Hawai’i.
As shown above, a family of dolphins escorted us during our last transit back to the Honokohau harbor at Kona, the island of Hawai’i.
Finally, I wish to thank all the wonderful people that made this marine project possible:
Gwen Jacobs, Steve Constable, Dallas Sherman, Khaira Ismail, Kevin Kelly, Michelle Choe, Ellen Koppenheffer, Jake Perez, Chris Armerding, John Souders, Jacques Lemire, James Barry, Jason Magalen, Brendan Hunter, Patrick Anderson, Max Sudnovsky, Steve Kennedy, Jason Hasler, Emily Wilson, Keith Olsen, Jan C War, Dean Towle, Keven Rinkenbach.
Videos from the survey can be viewed on ‘IkeWai Marine CSEM YouTube channel.
Our survey operation is improving daily, where the time for deployment & recovery of the CSEM, MBES, and Magnetometer systems are getting shorter. Thus, we can cover more area in the 14 hours of daily operation. Yesterday and Today we are surveying the north section of our survey area, starting from the Kiholo Bay where previous studies measured a substantial influx of groundwater into this Bay.
The images in the mosaic above show some various examples of the unprocessed MBES data. Note the variability in seafloor bathymetry at the surveyed area.
