RV Investigator Voyage IN2025_V05 EM124 Multibeam Echosounder Data

This record describes multibeam echosounder data collected on RV Investigator voyage IN2025_V05, 'Eruption, destruction and seafloor ecosystem recovery – Tonga 2022 eruption of the century', which departed Hobart on 10 Aug and ended in Brisbane on 01 Oct 2025 (local). The voyage’s first leg transited from Hobart to Nuku’alofa (10–19 Aug 2025), where science participants boarded. A mid-voyage transfer occurred on 05 Sep, and all science personnel disembarked in Nuku’alofa on 23 Sep before the final transit to Brisbane (23 Sep–1 Oct 2025).The EM124 provides a 1 degree by 1 degree angular resolution. The echosounder's nominal frequency is 12 kHz. Data are stored in *.kmall raw format for bathymetry and backscatter and *.kmwcd format for watercolumn backscatter at CSIRO. There are 1044 files totalling 140 GB of raw data and 1044 files totalling 186 GB of watercolumn data in this dataset. Sound velocity profiles were applied to this data during data acquisition. Bathymetry data contained in *.kmall format are corrected for motion and position. GPS tide was computed using the EGM2008 model and applied to the processed data. Processed data has had outliers removed. Additional information regarding this dataset, including further information on processing streams, is contained in the GSM data acquisition and processing report.