Processed multibeam bathymetry data and estimated eruption flow thickness from the East Pacific Rise, 9°50'N (MGL2602, 2026)

A bathymetric survey was completed using a Kongsberg EM122 echosounder along the East Pacific Rise and its flanks near 9°50'N in March 2026 onboard R/V Marcus G. Langseth cruise MGL2602. Survey lines were acquired at a typical vessel speed of ~4 kt (~2 m/s), with tracks spaced ~300 m to provide 100% bathymetric coverage. A small number of ping artifacts were removed manually at sea using QPS Qimera software. The final bathymetric grid was constructed using Qimera software at 10 m x 10 m node spacing. The thickness grid was calculated by taking the difference between the pre-eruption multibeam bathymetric data collected by AUV Sentry in 2018–2022 (Wu et al., 2022), and shipboard post-eruption bathymetric data collected in 2026 during cruise MGL2602. The pre-eruption AUV Sentry grid was down sampled to 10 m x 10 m, and co-registered with the 2026 shipboard data using bathymetric terrain features such as fault scarps and pillow mounds on the flanks of the ridge axis which were unaffected by the 2025 eruption. After applying a 4.1 m vertical shift to the Sentry grid, the depth difference was obtained. The grids are is in GMT-compatible netCDF format. The survey was supported by the U.S. National Science Foundation, awards OCE-2427181 and OCE-2427182.