IkeWai marine CSEM results first presented at AGU Annual Fall Meeting 2019

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.

CSEM System Packing & Demobilazation

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.

Loggers_and_Fishes
Data loggers of the Porpoise surface-towed receivers, and their associated fish.

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”.

Porpoise_Bar
Yes, there is actually a bar by that name in Kona.

Thank you all for following our survey blog!

Cheers,
Eric & the Survey Team

Marine Survey Completed!

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.

image003
Survey Area 1: North section of the Hualalai groundwater system. Includes 7 survey inlines and 3 crosslines. The color bar represents bathymetric depth that ranges from 10 m (red) to 100 m (blue).

image004
Survey Area 2: Middle section of the Hualalai groundwater system. Includes 2 survey inlines. The color bar represents bathymetric depth that ranges from 10 m (red) to 100 m (blue).

image001
Survey Area 3: South section of the Hualalai groundwater system. Includes 3 survey inlines. The color bar represents bathymetric depth that ranges from 10 m (red) to 100 m (blue).

image002
Total survey coverage along the Hualalai groundwater system. Total of 15 survey lines. The color bar represents bathymetric depth that ranges from 10 m (red) to 100 m (blue).

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

image2
A failed attempt to take a photo of the Porpoise array through a pair of binoculars.

image5
The team before the last recovery of the Porpoise array.

image2
Quoting Brenden: “we’re blonde, we’re making science, nothing can stop us!”.

image1
Quoting Max: “Well, maybe just blonde “.

Dallas_and_Me
Eric & Dallas in a moment of joy after the final recovery of the CSEM system.

image1
Crew group photo, from front to back: Khaira, Jake, Dallas, Max, Jason, and Eric.

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.

Surveying the Kiholo Bay Area

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.

20180913TotalCoverageToDate_North
Data collection coverage along the northern section of the survey area.

P1_4_Spectrograms
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.

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.

WaterColumn
Logging of multi-beam backscatter water column data using Hypack.

IMG_1014
Jason, Khaira, and Eric are discussing water column Multi-beam data, whereas Patrick is operating the G-882 magnetometer system.

Ike Wai Day 6 Screenshot_01
Recording of the magnetic data streamed from the G-882 magnetometer. The data is logged using Geometrics MagLog software.

image1
Our captain Max is enjoying the calm transit to Kiholo Bay.