Geophysics data collection includes bathymetry, magnetics and gravity measurements. Bathymetry is seafloor mapping using multibeam data. The magnetometer collects magnetics data and gravity data are collected by a gravity meter. John manages the bathymetric data, Maurice manages the magnetics data, and Gabby manages the gravity data.
This is John’s fifth ocean research expedition. He’s experienced in collecting geophysics data and works with magnetic modeling and gravity in his research as a graduate student. John enjoys being part of the geophysics team and learning to run the equipment and computer programs instead of being a watch stander. He plans the track lines for coverage and makes sure the data quality is good and he supervises the watch standers from 2 AM to 2 PM. Before getting on the ship, John wrote the multibeam processing code, tailoring it to the needs of this cruise. He designed the processing plan and set up the watch stander work flow. Using the code John prepared, the watch standers process the data in real-time allowing the other scientists onboard to use the bathymetric maps they create to plan the best dredging sites for rock collection.
Gabby has gravity measurements experience from a previous cruise, and she uses this type of data in her graduate program. The gravity measurements for this ridge are so strange that she thought there was something wrong with them. She and Maurice compared them to the magnetic data and though it’s very strange, the data sets make sense when taken together. They found very high mantle signatures in places where peridotites were recovered and low in areas with mostly basaltic rocks. Gabby is from Indonesia and initiated our outreach to over 300 Indonesian students!
Maurice supervises John and Gabby and the 2 PM to 2 AM watch standers. This is Maurice’s 49th cruise. As a marine geophysicist, he spends a lot of his time on the ocean! Maurice processes the magnetics data as it’s collected and will make further corrections using time-stamped records of the magnetic field’s diurnal changes when he’s back in his lab. He leads the team in interpreting all the geophysics data. In this ultra-slow spreading ridge segment, they have documented areas of no magnetic signal where the rocks collected are peridotite and there are low gravity readings. Maurice says this is a fantastic data set for a bizarre looking area and he looks forward to puzzling out the comprehensive tectonic story for this ridge section.