Anak Krakatau, Indonesia

Bathymetry and Elevation; Seismic reflection

Multibeam bathymetry data and seismic reflection survey data are recorded in x,y,z ASCII format from Anak Krakatau, Sunda Strait, Indonesia between Krakatau and Sebesi island. The data were collected during August-September 2019. The bathymetry survey was carried out using a Multibeam Echo Sounder. Bathymetry surveys were conducted from a wood vessel 6 GT equipped with Teledyne Reson T20-P Multibeam Echosounder, this R2sonic 2026 has Bottom Detect Range Resolution of 6mm, selectable swath coverage from 10 degrees to 160 degrees and depth range 1m to 500m. The Positioning system uses Differential Global Positioning System (DGPS) Trimble SPS 461 with OmniSTAR signal correction and computer-based navigation/data acquisition system with Qinsy Acquisition software. The survey vessel is fitted with motion sensors installed on the Multibeam Echosounder Transducers to compensate for vessel heave. Heave compensation is applied directly to the sounding data for the Multibeam Echosounder system. The shallow reflective seismic method was conducted by sound source and hydrophone towed on the back of the ship. The signals received by hydrophones were then channeled to Khron Hite 3700 Band Pass Filter before being recorded using Chesapeake SonarWiz Shuttle connected with SonarWiz 4.0 recording software to produce digital data. The Band Pass Acoustic Filter is set at a working frequency of 30 Hz to 3000 Hz, while the sparker firing rate is 0.5 seconds and the sweep rate is 0.25 seconds. The aim of this data collection was to better understand natural hazards such as submarine landslides and therefore determine how the landslide failed. Data was collected and submitted to BODC by Dr James Hunt, from the National Oceanography Centre, Southampton UK.

J. E. Hunt, D. R. Tappin, S. F. L. Watt, S. Susilohadi, A. Novellino, S. K. Ebmeier, M. Cassidy, S. L. Engwell, S. T. Grilli, M. Hanif, W. S. Priyanto, M. A. Clare, M. Abdurrachman & U. Udrekh (2021) Submarine landslide megablocks show half of Anak Krakatau island failed on December 22nd, 2018,