Check out our new results from applying electromagnetic geophysics to image the subduction zone structure on the seafloor off the North Island of New Zealand in a new Nature paper led by Columbia University and EM Geophysics Lab graduate student Christine Chesley
Joint Bayesian inversion of MT and CSEM data published
EM Lab graduate student Dan Blatter led a new paper on joint Bayesian inversion for marine magnetotelluric (MT) and controlled-source EM (CSEM) data to image submarine groundwater aquifers. The MT data is preferentially sensitive to the conductive parts of the model while the CSEM data is more sensitive of the more resistive low salinity aquifer. Joint inversion of the data yields the best resolution, as demonstrated with Bayesian uncertainty analysis.
Geophysical Journal International, Volume 218, Issue 3, September 2019, Pages 1822–1837, https://doi.org/10.1093/gji/ggz253
The paper is available for free here: https://academic.oup.com/gji/article/218/3/1822/5510458
Mapping offshore aquifers
Graduate student Chloe Gustafson and Professor Kerry Key published a new Scientific Reports paper on using marine EM to map large submarine groundwater aquifers on the US Atlantic Margin.
Gustafson, C., Key, K. & Evans, R.L. Aquifer systems extending far offshore on the U.S. Atlantic margin. Scientific Reports 9, 8709 (2019) doi:10.1038/s41598-019-44611-7
The paper is freely available: https://www.nature.com/articles/s41598-019-44611-7
Selected stories from popular science news media coverage:
Morton, M. C. (2019), Huge aquifer imaged off the Atlantic coast, Eos.
Seeker (2019), “Scientists Just Discovered Fresh Water Under the Ocean”.
BBC News World Service (2019) “Could there be drinking water under the seas?”
EM Lab completes survey of Alaskan Subduction Zone
This has been a year for subduction zone electromagnetic surveys. In February we completed a large-scale survey of the Hikurangi Trench off the North Island of New Zealand, and now we just completed a complementary large-scale survey of the Alaskan subduction zone. Principal investigators Kerry Key and Samer Naif led a large team that included Lamont graduate students Christine Chesley and Tanner Acquisto and postdoc Julen Alvarez-Aramberri onboard the R/V Sikuliaq offshore of the Alaska Peninsula. The electromagnetic and magnetotelluric imaging data collected using 159 seafloor stations and a deep-towed transmitter will be used to study fluids along the subduction zone plate boundary and how they impact plate tectonics and seismicity.
EM Lab completes deep tow operations in extensive survey of the Hikurangi Trench off New Zealand
PI Samer Naif led a large team that included Lamont graduate students Christine Chesley, Bar Oryan, and Daniel Blatter onboard the R/V Roger Revelle in the waters east of North Island, New Zealand to carry out a marine electromagnetic (EM) survey of the Hikurangi subduction zone. The project includes over 168 seafloor EM receiver stations and over 400 line-km of transmitter deep-tow tows, making it the largest marine EM experiment at a subduction zone yet. The data will allow the team to assess the role that fluids play in both generating subduction zone earthquakes, and in controlling the seismic behavior of faults more generally.
Click here to see photos and read the cruise blog.
EM Lab completes first magnetotelluric survey to target subglacial groundwater in Antarctica
Graduate student Chloe Gustafson and Prof. Kerry Key camped on the Whillans Ice Stream for six weeks as part of a four person team using geophysics to study the subglacial environment. The team collected 44 magnetotelluric (MT) stations that will be used to image groundwater at Subglacial Lake Whillans and the nearby grounding zone.
Click here to learn more about their epic trip that included driving snowmobiles over 900 miles across the ice stream and hauling over 15,000 pounds of cargo between three different camps.