Christoph Kraus

Christoph is an Engineering Geologist at Beca in Wellington. His key interests include analysing complex geology, mitigating geohazards and undertaking fieldwork. He’s conducted fieldwork in in a range of different geological settings in New Zealand, Patagonia, Samoa, and Antarctica. Christoph also pilots UAVs to support and enhance fieldwork and analyses.

Abstract

Designing a breakwater in Apia: results, challenges and recommendations

The Port of Apia, Samoa, is undergoing a development project to upgrade its facilities and infrastructure. As part of this project, an extension and remediation of the existing breakwater have been assessed to provide further protection from swell waves and cyclones, thereby reducing delays in port operations. To inform the design of the breakwater, three boreholes were drilled in Apia Harbour, each recovering ~20m of very loose/soft sediments overlying basaltic lava flows. This recent borehole data was combined with the historical data to develop a geological ground model of the site. Using the ground model, liquefaction and slope stability analyses were undertaken for the breakwater extension and remediation. Analyses indicate likely liquefaction of the loose sediments leading to lateral displacement of the breakwater. The results were compared with the performance of the breakwater during the 2009 Mw8.1 earthquake. Options to improve the seismic resilience were considered with the emergency preparedness option being taken forward for detailed design.